# Wastewater pump motors tripping on decel



## hansonmaster (Dec 5, 2017)

mle33 said:


> I feel this is kind of a long shot, but im just hoping maybe someone will at least throw out an idea that we havent had yet. i have looked into this issue, my co worker has looked into it, we even hired a very well respected local controls electrician contractor to take a look and still, no solution. a mystery i guess. i am to the point that i feel it might be getting dangerous and out of my league.
> 
> 
> 
> ...


Your engineer is correct on wire and breaker sizing. Did you megger the feeders? With the wire being that undersized I see a possibility of insulation breakdown. I could see that wire lasting about 5 years before starting to fail. 

With what you are describing I would say you have a very dangerous situation that needs to be fixed right away. You run the risk of loosing the entire facility. Where will all that wastewater end up if you loose everything? I would get an engineer to go through everything in detail and develop stamped drawings to make the necessary changes. Going that route will put the liability on that engineer. I wouldn't do anything to the system without that being done first. Then hire a good electrical contractor to do the work. Hopefully you have a way to set up bypass pumping during the station outage.


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## micromind (Aug 11, 2007)

Most likely the stop ramp is set too long. 

Since these are centrifugal pumps, when the stop command is given, the soft-start begins ramping the voltage down. The motor then draws more current in order to maintain speed, this current is above the breaker rating so it begins to 'ramp up' to a trip. In your case, the breaker will trip before the soft-start ramp down is complete. 

It's very likely that the trip unit in the breaker is getting weak because of all the tripping. 

A centrifugal pump with a soft-start should ramp down as quickly as the mechanical and piping system will allow. 

Replacing the breaker and wire with larger capacity will solve the tripping issue but you still have a motor that's warm/hot from normal operation and is subject to huge current during stopping.........not the best idea.......


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## mle33 (Oct 18, 2013)

micromind said:


> Most likely the stop ramp is set too long.
> 
> Since these are centrifugal pumps, when the stop command is given, the soft-start begins ramping the voltage down. The motor then draws more current in order to maintain speed, this current is above the breaker rating so it begins to 'ramp up' to a trip. In your case, the breaker will trip before the soft-start ramp down is complete.
> 
> ...


after so many incidents with pump 2, that is why we decided to put in a new breaker after we made the soft start changes, in case it was simply worn out from so many trips. it continued to trip just as much.
the ramp down time has been at 25 seconds for the entire time the station has been in use (im told...), but we have tried it as low as 7 seconds with no different results. afraid to go any lower.
also, if the ramp down time was the issue, wouldnt the trip occur every single time the pump is ran?


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## mle33 (Oct 18, 2013)

hansonmaster said:


> Your engineer is correct on wire and breaker sizing. Did you megger the feeders? With the wire being that undersized I see a possibility of insulation breakdown. I could see that wire lasting about 5 years before starting to fail.
> 
> With what you are describing I would say you have a very dangerous situation that needs to be fixed right away. You run the risk of loosing the entire facility. Where will all that wastewater end up if you loose everything? I would get an engineer to go through everything in detail and develop stamped drawings to make the necessary changes. Going that route will put the liability on that engineer. I wouldn't do anything to the system without that being done first. Then hire a good electrical contractor to do the work. Hopefully you have a way to set up bypass pumping during the station outage.


ha. bypass pumping. that wouldve been a smart idea when the station was being implemented lol. we do have some portable bypass pumps but they are only large enough for our smaller stations. this is one of our "master" stations and we have absolutely no plan in place for if 3 or more pumps fail here.

i have an additional electrician coming in to look at everything tomorrow. i hope he has the ability to at least help me convince my boss that we need a legit engineer involved.

i did megger all the wires. from the jbox down to the pumps, from jbox to inside at the MCC, and even across the room from the MCC to the main breaker. someone had the idea that maybe my 1000v megger isnt sufficient and i should locate a bigger one to try to use, but i would assume an issue this persistent would be detectable by the megger i always use?


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## hansonmaster (Dec 5, 2017)

mle33 said:


> ha. bypass pumping. that wouldve been a smart idea when the station was being implemented lol. we do have some portable bypass pumps but they are only large enough for our smaller stations. this is one of our "master" stations and we have absolutely no plan in place for if 3 or more pumps fail here.
> 
> i have an additional electrician coming in to look at everything tomorrow. i hope he has the ability to at least help me convince my boss that we need a legit engineer involved.
> 
> i did megger all the wires. from the jbox down to the pumps, from jbox to inside at the MCC, and even across the room from the MCC to the main breaker. someone had the idea that maybe my 1000v megger isnt sufficient and i should locate a bigger one to try to use, but i would assume an issue this persistent would be detectable by the megger i always use?


I am guessing the wire is only rated at 1000VDC so using a larger megger could (likely would) result in insulation destruction. Not sure why anyone would recommend using a 5000V megger unless they just don't know what they are talking about. Definitely not recommended.

Hope your electrician finds the issue. Keep us posted. I am very interested to know what's going on. You might want to locate a bunch of pumper trucks and have them on standby just in case


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## mle33 (Oct 18, 2013)

hansonmaster said:


> I am guessing the wire is only rated at 1000VDC so using a larger megger could (likely would) result in insulation destruction. Not sure why anyone would recommend using a 5000V megger unless they just don't know what they are talking about. Definitely not recommended.
> 
> Hope your electrician finds the issue. Keep us posted. I am very interested to know what's going on. You might want to locate a bunch of pumper trucks and have them on standby just in case


ill update tomorrow. thanks! love this forum. i learn from each and every reply. so cool to have so much knowledge from some really experienced guys all here in one place


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## MikeFL (Apr 16, 2016)

@JRaef is a wiz at this.
And I believe @just the cowboy works with similar motors.

I also renamed the thread. You had said you typed it in a hurry. Maybe some more motor guys will chime in. We have some really good ones on here, but I'm not one of them.


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## BillyMac59 (Sep 12, 2019)

What about contacting the manufacturer? I've had good luck contacting them through the company from which we've purchased the hardware. They may have engineers/techs who are experts with the drive and its application. This service usually doesn't cost anything.


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## mle33 (Oct 18, 2013)

MikeFL said:


> @JRaef is a wiz at this.
> And I believe @just the cowboy works with similar motors.
> 
> I also renamed the thread. You had said you typed it in a hurry. Maybe some more motor guys will chime in. We have some really good ones on here, but I'm not one of them.


ah. thank you!


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## mle33 (Oct 18, 2013)

ValeoBill said:


> What about contacting the manufacturer? I've had good luck contacting them through the company from which we've purchased the hardware. They may have engineers/techs who are experts with the drive and its application. This service usually doesn't cost anything.


i did not personally do this, but my coworker said he attempted with schneider (the soft start manfctr) and was escalated to their highest "level", and still did not resolve anything. i may try to do this myself as he is not always the best at communicating things


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## SWDweller (Dec 9, 2020)

How long did the facility run before the problem started? 
Any new capacitors on the incoming line or changes to those?
What else electrically has changed since the problem started. 
Do all 4 of these pumps push into a the same header/pipe? Are there check valves? Have those been touched recently?
Repeating, pumps trip only on decel. During a normal course of operation what is the run cycle?
Staging on 1 thru 4 then off 4 to 1? Do you vary the lead and lag pumps for wear?

Do any of the tripping breakers have settings? You say tripping, on what? Long time, short time, ground fault to mention a few. What about the main breaker?


I agree that a bigger megger is not a solution. How long did you hold each test?


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## mle33 (Oct 18, 2013)

SWDweller said:


> How long did the facility run before the problem started?
> Any new capacitors on the incoming line or changes to those?
> What else electrically has changed since the problem started.
> Do all 4 of these pumps push into a the same header/pipe? Are there check valves? Have those been touched recently?
> ...


allegedly, 5 years, this being year 6. ive only worked here for about 2.

no new capacitors.

we did have a contractor come in and install a new backup float system, as well as a relay based control system (previously, the controls were through ethernet only, meaning if the ethernet switch in the main cabinet failed, the entire station failed). i have considered the fact that the problem started not too long after they did the work, but i cant for the life of me wrap my mind around what they couldve done to affect this??

they each have individual pipes and check valves immediately after leaving the wells, but yes they all push into 1 single force main just after. pump 4s check valve was recently serviced cause it kept getting stuck open. it has been repaired.

sorry im an idiot what exaclty do you mean by what is the run cycle?

yes we vary the lead/lag. there are two wells, 1 and 2 are in one and 3 and 4 in the other. so when we set up the cycle we like to altnerate between wells so we'll do like 1,3,2,4 or 2,3,1,4. etc.

ok definitely not going to bother with a bigger megger then. i held my tests for 1 minute.

yes the breakers do have little dials on them. i confirmed that they matched with our identical station/set up at another location but thats as far as ive gone with the breaker settings. not sure how to tell what exactly is triggering the trip? is there a way to tell?


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## wiz1997 (Mar 30, 2021)

Can you allow the pump to coast to a stop on it's own?
If possible change the way the drive stops the motor.
If it will coast to a stop without tripping the breaker that will indicate that your deceleration time needs to be adjusted when you have the drive in ramp down mode.
If coast to a stop can not be done, per micromind's suggestion, adjust your decel time.


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## Jlarson (Jun 28, 2009)

What else changed?

I've never been a fan of ramp down on lift pumps, we'll do weight and lever checks on larger pumps if we have to to avoid slamming.


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## micromind (Aug 11, 2007)

Jlarson said:


> What else changed?
> 
> I've never been a fan of ramp down on lift pumps, we'll do weight and lever checks on larger pumps if we have to to avoid slamming.


Even with a VFD, it's not going to be a completely smooth ramp and besides, what if the power fails? No ramp at all there.......

This is one area where mechanical beats electrical every time.


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## CAUSA (Apr 3, 2013)

Any pressure transducer in the piping? If yes before the check valve or after?

I would get Mgmt to rent a VARs meter and _trend the system. I know it’s a little over kill but it removes doubt.

Is the GPM monitored? Is there any change?

I know the Question is strange but it’s for relationship to the Impeller condition. That’s one factor that can change. But the ramp up will show this as well. Not tripping but lower/higher current._


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## gpop (May 14, 2018)

My first though when i see a problem like this is a cycling problem with no de-bounce. 
Scada should be capable of monitoring the plc run signal and the softstart running signal. The downside is due to the decel time scada may not see a problem as the softstart might be reporting running during decel. 
If you have a pump that's hardwired to stop on a low level float and the float is bouncing (float is shutting off pump before scada) it will still have a active run signal from scada (scada did not see pump stopping due to softstart reporting running during decel) and try to relight the motor. Rapidly repeat this and you have a motor that hunting at the limit set in the softstart which is probably 3-600% and somethings going to trip. 
Personally i would disable the floats for a day and see what happens if i did not have a data recorder on hand or wire a input from the float to scada and have that kill the run signal then add a debounce in the program. 

Please do not meg at 5kv as that would be a expensive mistake.


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## mle33 (Oct 18, 2013)

gpop said:


> My first though when i see a problem like this is a cycling problem with no de-bounce.
> Scada should be capable of monitoring the plc run signal and the softstart running signal. The downside is due to the decel time scada may not see a problem as the softstart might be reporting running during decel.
> If you have a pump that's hardwired to stop on a low level float and the float is bouncing (float is shutting off pump before scada) it will still have a active run signal from scada (scada did not see pump stopping due to softstart reporting running during decel) and try to relight the motor. Rapidly repeat this and you have a motor that hunting at the limit set in the softstart which is probably 3-600% and somethings going to trip.
> Personally i would disable the floats for a day and see what happens if i did not have a data recorder on hand or wire a input from the float to scada and have that kill the run signal then add a debounce in the program.
> ...


the normal operation is on/off is controlled by a level transducer. the floats are only activated when the transducer fails. though i guess its possible that the low-low float would override and shut the pump off even when the station is in transducer mode. i need to investigate this, since we did recently have contractors come and make changes to the controls, maybe they made a change im not aware of. had not considered this, thank you.


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## mle33 (Oct 18, 2013)

CAUSA said:


> Any pressure transducer in the piping? If yes before the check valve or after?
> 
> I would get Mgmt to rent a VARs meter and _trend the system. I know it’s a little over kill but it removes doubt.
> 
> ...


im not familiar with a VARs meter but im going to research that now. the GPM is monitored but it has not indicated any change during the events. i will look further into this though. i already had the idea of the impellers being worn but i found documentation of pump run characteristics from when the station was only 2.5 years old, and the amp draws on start/stop are not far off now from what is documented there.


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## mle33 (Oct 18, 2013)

Jlarson said:


> What else changed?
> 
> I've never been a fan of ramp down on lift pumps, we'll do weight and lever checks on larger pumps if we have to to avoid slamming.


when we attempted to lower the ramp down to as low as 7 seconds we did start experiencing some minor slamming.


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## mle33 (Oct 18, 2013)

wiz1997 said:


> Can you allow the pump to coast to a stop on it's own?
> If possible change the way the drive stops the motor.
> If it will coast to a stop without tripping the breaker that will indicate that your deceleration time needs to be adjusted when you have the drive in ramp down mode.
> If coast to a stop can not be done, per micromind's suggestion, adjust your decel time.


i have not looked into this but i will today. when i lowered the soft starts ramp down to 7 seconds we started experiencing minor slamming so im wondering how bad the slamming would be if i got rid of the ramp down all together. going to try it today and see. thank you.


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## SWDweller (Dec 9, 2020)

Dials on the breakers, depending on who's breakers and what vintage they are the dials may have different values. Most of the the ones I have seen on older equipment were a percentage of FLA for the breaker. You could adjust the breaker to be a closer value than just the name plate of the breaker. Good for starting motors and their loads. a couple of links to different types of dials.
The pics zoom better when I use the pages.





Cutler Hammer HMCP400X5WS10 3 Pole 400 Amp 600 Vac Breaker w/Shunt Trip (N5) | Electrical Power and Control Consultants


Cutler Hammer | Westinghouse HMCP400X5WS10 3 Pole 400 Amp 600 Vac Circuit Breaker (Appearance May Vary From Photo) Instantaneous Trip Unit Shunt Trip - SNT3 ...




electricalpowerandcontrol.com













6 Adjustable Tripping Settings of a Circuit Breaker You MUST Understand | EEP


There are (at least) six basic adjustable tripping settings (functions) you really should understand in order to fully understand how circuit breaker




electrical-engineering-portal.com





If you have the first type then there will be no indication of the type of trip. Second type should tell you what trip happened. Lot more expensive equipment.

Run cycle, turn on from transducer, (gleaned from text) ramp up then ? second motor? third? 
Length of run time? Length of time between motor starts? Starts per hour? 
Are the motors rated for a given number of starts per hour? I have seen motors that said 4 starts per hour. They got hot during starting.
In the back of my mind I keep coming to around the concept of back EMF. The motors are turning off and they pass through an harmonic generation area of the off cycle. Causing more EMF to be generated.

You mentioned different controls, recently? Are the controls shielded ENET? Verify ground shield To the connectors. Also verify the ground shield for any and all control cables. Needs to be for sure grounded once at the control location. NOT a star ground. I have never gotten one of those to work. Star ground is center ungrounded and the out edges are grounded. Least wise what I call them.


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## just the cowboy (Sep 4, 2013)

As someone said a mechanical issue is more than likely the case, I would not waste time till I ruled that out. If it was just one pump maybe motor and controls, do you have any trends from when it was working. If you are deceling and have been doing it that way and it has been working, chances are your load changed. Before when you went into decel and reduced voltage the motor was able to continue to push the load till it stopped. Now the load must of increased to cause this issue. 
Think of it this way:
You have four wheel barrows full that you push up a ramp with help ( run power ).
For years you were able to get a running start ( Run power ) and push the last one up ( Decel) without help (full voltage ) and empty it.
Now someone raises the angle of the ramp ( load )
No matter what you can't overcome that load and you collapse ( breaker trips).



Have you looked at the line voltage from the MCC main when it is in decel mode, does it change? How does the current look on startup?

Cowboy


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## CAUSA (Apr 3, 2013)

To prevent me from chasing my tail on a intermittent problem.

I start a basics flow chart of what was changed versus what was checked and by what system it was checked by,

-(calibration of the meters and testing equipment verified and accurate).

-list of equipment changed to the right trip curves to the load application. the breaker that was changed does it have the right trip curves and operating parameters for the application?

-I would also thermal Imaging the entire system. Looking for hot spots that are hidden and all Buss connections.(due to so many changes and uncertainty).

-and record the findings to the flow chart,? so the process of elimination can happen and pin point the True issues.

On the thermal imaging. This has to be done live so, if no viewing windows. You have to suit up in the right ARC flash material. Or contract it out and have it documented.


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## mle33 (Oct 18, 2013)

SWDweller said:


> Dials on the breakers, depending on who's breakers and what vintage they are the dials may have different values. Most of the the ones I have seen on older equipment were a percentage of FLA for the breaker. You could adjust the breaker to be a closer value than just the name plate of the breaker. Good for starting motors and their loads. a couple of links to different types of dials.
> The pics zoom better when I use the pages.
> 
> 
> ...


ok i have a ton of reading and googling to do after going through this reply. i appreciate all the info. several things here i had not considered at all and dont have much knowledge on to begin with. the breakers are the first type.


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## Jlarson (Jun 28, 2009)

When they messed with the controls did they change how they cycle?


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## paulengr (Oct 8, 2017)

1. I work on soft starts all the time.
2. I do Schneider Altistarts occasionally. They kind of suck but not as bad as Cutler Hammers.

2. It is VERY RARE to see anyone using ramp down. On a soft starter (in general,
A. Coast to stop. This just cuts the power off and lets the motor ramp down naturally (or not if the check valves have failed...).
B. DC injection braking. This operates FASTER than coast to stop. A LOT faster. I've squealed belts on huge inertia loads this way. It may require extra hardware and because it is injecting additional current (up to 400% of FLA, DC on a Benshaw RB2) it counts as an extra start in terms of heating.
C. Ramp down. This option can ONLY go slower than coast to stop. AND this is going to be a lot rougher than many people realize. Take a look at this chart:


https://www.ee.co.za/wp-content/uploads/2017/10/mike-rycraft-137-11-2017-fig7.jpg



Normally this chart is used for talking about starting current with a motor and the advantage of using a soft start. So let's get one thing clear. Which came first, torque or current? If we are talking about the output power/torque of a motor, current is a consequence of the load. If the load goes up, so does the current. If we uncouple the pump we get a no load current. Let's put some real world numbers to this. Say we have a "generic" North American 4 pole pump motor. So NEMA Curve B means it should have about a 3% slip. So with a synchronous speed of 1800 RPM, the name plate speed at 100% of FLA and 100% load should be 97% of 1800 or 1746 RPM. If the load is 50% of name plate then RPM will increase slightly to the halfway point or 1773 RPM. This works in reverse too...the motor can handle up to somewhere around 200-300% of rated torque before it reaches the magnetic limit and stalls out. We are operating to the right of the peak of the curve. So what happens when we reduce the voltage? Current (and torque) is proportional to the square of the voltage so even a small 10% reduction in voltage causes a huge 19% decrease in torque. But remember...current is a CONSEQUENCE of torque, not the other way around. So if I decrease the voltage, the motor is going to slip more and the current is going to go up. So when I soft stop, I'm going to very quickly get into a situation where I'm seeing locked rotor current. The PEAK current is reduced thankfully and that's how we are controlling things (just as we'd do the same thing in a soft starting condition). But the fact is that current is going to go up to whatever we limit it to because we are doing the same thing as starting, except in reverse.

Now considering the breakers I will start with this. When is a "circuit breaker" not a "circuit breaker"? Whenever the device falls outside of what UL allows. According to UL a molded case "circuit breaker" has a thermal trip designed to match the thermal characteristics of wire (not motors) and has an instantaneous trip that is limited to 10 times the name plate rating. Motors fall WAY outside these requirements. So when it comes to motors often we use various devices that look like circuit breakers but aren't. Take for instance this gem:



https://i5.walmartimages.com/asr/b044ac2d-c977-412e-8cac-0076ef0d0d36_1.8d9eef83519756a9da9146d9e1c5066c.jpeg



To the untrained eye this looks like a 3 A circuit breaker but it's definitely NOT a circuit breaker. Cutler Hammer calls it a "motor circuit protector" (MCP). It does not have the thermal protection trip in it because in a motor circuit, the overload relay performs that function. Even more importantly, motors can easily exceed the normal UL 10x rating instantaneous trip requirement. This one has an adjustable instantaneous trip that can only be set to 30 A (10 x rating) but this device has a secret. Inside it has a hairpin turn that current limits so that the motor cannot draw more than 10x FLA.

Many engineers are unaware of the world of motor protective devices and will often mistake this device for a simple "circuit breaker" when in fact it is something else entirely. So if the motor was say rated for "100 A" and the MCP was rated for say "120 A" this might in fact be a correct installation but if you didn't know what you were looking at you might try to switch it to a 250 A rated breaker (250% of FLA) thinking that it is grossly undersized.

BUT even if you did this, the breaker is still rated WAY below the motor stall current. So it can still easily trip during starting, and with a soft starter during both starting and stopping.

Now when someone goes in to tune the system up especially knowing you have a tripping problem, the natural inclination of course is to increase the soft stopping time or decrease current limits or both. Either one amounts to the same thing....we are going to be drawing current above the trip point of the breaker for longer periods of time and make the problem worse, not better. I would say that 90% of the time when I get a call about a soft start tripping issue if it's not an actual fault, all I have to do is crank the settings up a little higher (start or stop faster) and the problem goes away.

Finally, something doesn't pass the smell test here. There are standard name plate ratings for motors and the numbers don't sound like a standard size (250, 300, 350, 400, 450, 500, 600). Whenever I see an oddball motor it's usually a compressor company playing games or something truly oddball like electronically commutated motors. Check that name plate data carefully.

So my suggestion is do your homework. First go back and check the actual trip curves of the devices involved and compare that to the motor name plate current, locked rotor current (should be marked or a code letter on the name plate), and peak torque (motor data sheet only). It should be very obvious what is going wrong. My gut reaction is that the breaker is sized or set up wrong or that you never had a breaker in the first place.


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## mle33 (Oct 18, 2013)

update : unfortunately i take care of 3 plants and 32 other lift stations, so while im trying to focus on one thing im constantly getting called off to put out fires all over town. which is quite overwhelming considering im only in my 2nd year of even being in this field, and while i do have 1 other electrician, im essentially on my own as his skills are subpar. so i return to this issue/this thread as i can.

anyway. an electrician that has a ton of experience with controls/motors came out last friday. he mentioned alot of the things you guys have mentioned here. we were forming a plan of attack when, apparently, the company he works for decided they needed to send an engineer to help out. i was excited about this until in walks a 23 year old who graduated with his engineering degree like 5 minutes ago. smart kid. absolutely no field experience. kept making suggestions related to VFDs and i had to remind him 4-5 times that these are not VFDs.

his final solution was to put pump 1 in "freewheel" or , "coast to stop" over the weekend. pump 2 got its contactor coil changed (previously only the contacts themselves were changed). pumps 3 and 4 were left alone.

pump 1 tripped MCC breaker on sunday evening.
pump 3 tripped MCC breaker on sunday morning.
pump 2 did not trip over the weekend.

pump 2 had been our biggest issue, but it has fooled us before by going almost a week with no issues, then beginning to trip frequently once again. im hesitant to believe changing the coil solved our problems, but i could see how a weak coil could possibly cause our issue. thoughts?

pump 1 seemed to do ok in "freewheel stop", as in i watched it run several cycles and it was not slamming the check valve which surprised me. i was hopeful wed found our solution. but it did end up tripping after 2 days.

im going to try and post photos of the breaker and the motor nameplate later today, maybe seeing whats actually installed can help here


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## mle33 (Oct 18, 2013)

paulengr said:


> 1. I work on soft starts all the time.
> 2. I do Schneider Altistarts occasionally. They kind of suck but not as bad as Cutler Hammers.
> 
> 2. It is VERY RARE to see anyone using ramp down. On a soft starter (in general,
> ...


this is super interesting. i feel pretty ignorant about "breakers" right about now. i have a ton more research to do. i wish i could dedicate an entire 2-3 days to this.


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## Almost Retired (Sep 14, 2021)

I agree with @gpop
You stated the one thing that was changed just before this happened.

A CONTRACTOR INSTALLED A NEW FLOAT SYSTEM.

I was once told that when I heard hoof beats to think horses, _Not Zebras_.
you said that station ran for 5 years as it was. think about that.

The contractor *can*_*not*_ be expected to know what happens in the programing in your system. Neither can an engineer that gave him the specs to install it. Neither of them came and looked at your programing, or your existing wiring.

I sincerely believe you need to get some of those control guys you had there to look at the "new" floats and wiring as well as how they interface with the PLC and then the Programing in the PLC.

You need to build your own wiring diagram of what was installed by hand and eye checking every single wire connection to every thing existing. then compare it to any existing info you have

you need to understand how the PLC handles the info it is getting, as well as verify that something new has not been connected in the wrong place, which means the wrong input.

if you have PLC guys in your company get with them and figure out together what the program is actually doing. other wise get the control gurus from earlier back on site.


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## mburtis (Sep 1, 2018)

Here is something stupid simple I'm sure you have already checked. This sorta goes along with the idea of verifying the controls. Have you visually watched the level in the pit through a full cycle, to verify the turn on point and the shut off point and possibly even test the low low point. Have you verified that the level sensor and/or backup floats are working as they should. I only mention this because I ram into it once on a pump station. The start float was stuck on so it would pump down till the low float shut it off but then it would kick on as soon as the shut off float came off, so it was just sitting there fluttering on and off until either the overload or the line fuses blew. Since it seems to be affecting all the pumps somewhat randomly, I would be more likely to look at something control wise or program wise, not nessasarily the motor and starters. This is of course unless you have an incoming power problem like a dropped phase or massive voltage drop or something.


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## mburtis (Sep 1, 2018)

One other thing. You said when the undersized wire and breakers were pointed out you attempted to compensate by adjusting the drives? Did you adjust the current limits etc or something? Do you have any documentation from initial commissioning that you could use to verify all the setting in the soft starts are the same as when the station was working properly.


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## just the cowboy (Sep 4, 2013)

mle33 said:


> his final solution was to put pump 1 in "freewheel" or , "coast to stop" over the weekend.
> 
> pump 1 tripped MCC breaker on sunday evening.


This is what don't make sense, regenerative voltage/current may have tripped on decel put not with coast to stop.


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## micromind (Aug 11, 2007)

If the water in the pit is turbulent, the new floats (if you're using them) might chatter a bit at first and at the end of the cycle.

How about disabling the floats and using only the transducer?

If the new control system is relays and no time delay, it'll cause trouble by chattering at the start and stop. Any kind of chattering will trip a breaker.


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## MikeFL (Apr 16, 2016)

mle33 said:


> update : unfortunately i take care of 3 plants and 32 other lift stations, so while im trying to focus on one thing im constantly getting called off to put out fires all over town. which is quite overwhelming considering im only in my 2nd year of even being in this field, and while i do have 1 other electrician, im essentially on my own as his skills are subpar. so i return to this issue/this thread as i can...


The situation is far above the experience level of a 2nd year man. They need to pay someone to come in, someone who is qualified. No more 5 minute graduates. An established company in the area who will do what it takes to get it right.


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## joe-nwt (Mar 28, 2019)

I've been following along with interest and agree it's time to put the power end of things on the back burner and focus on the controls. When things work with no issues for several years and one motor starts acting up, that's one thing. But if more than one motor is acting up, you have to look at things common to all: controls, or possibly an intermittent incoming power issue.


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## paulengr (Oct 8, 2017)

just the cowboy said:


> This is what don't make sense, regenerative voltage/current may have tripped on decel put not with coast to stop.


A soft start cannot do regenerative braking at all. It’s not a drive.

You can slow down two ways. You can reduce the voltage causing the motor to essentially stall out. This is basically just extending the stopping time slower than coast to stop. You can inject DC into the motor and do DC injection braking.

You might somehow try to do braking while in cycloconverter mode. Some soft starts have the ability to operate as a cycloconverter. This is an old method of variable speed control but limited to 30 Hz or less (typically 10 Hz or less). The soft start simply skips AC sine wave cycles allowing it to create variable speed with an SCR drive. It works a lot better than it sounds and it can probably do regenerative operation but I have never seen anyone attempt this and even mentioning this operating mode is way off in the weeds.


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## JRaef (Mar 23, 2009)

*First, check to see if the breakers feeding the soft starters have Shunt Trips inside of them, wired to the Soft Starter trip contacts.* This is common in some soft starters. 

The Soft Starter has a "shorted SCR" detection circuit that then trips the contact wired to the Shunt Trip in the breaker. The WAY a soft starter detects a shorted SCR is to look for a LACK of a voltage drop across the SCR when it is not gated on. In other words the Soft Starter stops gating the SCR on and then looks for a voltage drop across it, if there isn't one, it assumed the SCR did not turn off, which means it is now shorted. The thing is, that circuit can be tricked by regeneration from the motor, especially during Deceleration, if there is enough residual magnetism in the motor core. So what can happen is that your Soft Starter is decelerating, but is turning off BEFORE your check valve is closed, so flow is reversing and the residual magnetism left in the motor core is allowing the motor to be a generator for a second or two, which puts a voltage on the motor leads and fools the shorted SCR detection circuit into thinking the SCR failed to turn off when it was told to.

So the trick to avoiding this is to make sure the decel ramp time is LONGER than it takes for the valve to close. If it was set up and worked correctly for a long time and just started this behavior, it usually means something has changed in the check valve. If it is a hydraulically activated "pump control valve", someone may have messed with the timer, or bent a limit switch that is supposed to signal to the control system that the valve has closed. If it is a swing check valve, it may be getting stuck open a little too long, as in it needs to be serviced.

If you want to test this out (again, IF the breaker has a Shunt Trip), disconnect the shunt trip wiring.

If not, then it's more likely related to what Micromind said earlier, as it is Decelerating, the current is increasing and causing the trip, it's a problem that can happen in some pump applications. Some soft starters have a more controlled Decel profile to avoid this, others do not. I've never been too fond of the Altistart soft starters, I have had a lot of trouble with them over the years.


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## just the cowboy (Sep 4, 2013)

paulengr said:


> A soft start cannot do regenerative braking at all. It’s not a drive.
> 
> You can slow down two ways. You can reduce the voltage causing the motor to essentially stall out. This is basically just extending the stopping time slower than coast to stop. You can inject DC into the motor and do DC injection braking.
> 
> You might somehow try to do braking while in cycloconverter mode. Some soft starts have the ability to operate as a cycloconverter. This is an old method of variable speed control but limited to 30 Hz or less (typically 10 Hz or less). The soft start simply skips AC sine wave cycles allowing it to create variable speed with an SCR drive. It works a lot better than it sounds and it can probably do regenerative operation but I have never seen anyone attempt this and even mentioning this operating mode is way off in the weeds.


I did not mean that the ss was doing regen, I was saying if the motor was doing anything it should not go back if SS is off/coast


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## mle33 (Oct 18, 2013)

Almost Retired said:


> I agree with @gpop
> You stated the one thing that was changed just before this happened.
> 
> A CONTRACTOR INSTALLED A NEW FLOAT SYSTEM.
> ...


the control guys were asked to come back almost immediately after the problem began. they "looked over" everything and determined that this issue was not a result of anything they did or changed. we dont have a PLC guy, thats expected to be me lol. i only even learned how to utilize rockwell software (self taught entirely) last year. i barely know wtf im doing when i get into once so i dont really mess with anything. from this and several other comments, i am presenting the idea of disconnecting the floats today and hoping boss will go for it.


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## mle33 (Oct 18, 2013)

JRaef said:


> *First, check to see if the breakers feeding the soft starters have Shunt Trips inside of them, wired to the Soft Starter trip contacts.* This is common in some soft starters.
> 
> The Soft Starter has a "shorted SCR" detection circuit that then trips the contact wired to the Shunt Trip in the breaker. The WAY a soft starter detects a shorted SCR is to look for a LACK of a voltage drop across the SCR when it is not gated on. In other words the Soft Starter stops gating the SCR on and then looks for a voltage drop across it, if there isn't one, it assumed the SCR did not turn off, which means it is now shorted. The thing is, that circuit can be tricked by regeneration from the motor, especially during Deceleration, if there is enough residual magnetism in the motor core. So what can happen is that your Soft Starter is decelerating, but is turning off BEFORE your check valve is closed, so flow is reversing and the residual magnetism left in the motor core is allowing the motor to be a generator for a second or two, which puts a voltage on the motor leads and fools the shorted SCR detection circuit into thinking the SCR failed to turn off when it was told to.
> 
> ...


not sure if this is the right terminology but our check valves are "passive". meaning they just swing back and forth with the water pressure. they do have hydrauliuc cushioners but those were all serviced and according to my mechanics, all good.
question, if what you described is the case, wouldnt the SS itself show a fault?


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## mle33 (Oct 18, 2013)

joe-nwt said:


> I've been following along with interest and agree it's time to put the power end of things on the back burner and focus on the controls. When things work with no issues for several years and one motor starts acting up, that's one thing. But if more than one motor is acting up, you have to look at things common to all: controls, or possibly an intermittent incoming power issue.


the last thing im going to try myself is disconnecting the floats entirely and seeing if that helps. incoming power seems to be ok, we have multiple monitoring equipment on the incoming and they all show good.


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## mle33 (Oct 18, 2013)

MikeFL said:


> The situation is far above the experience level of a 2nd year man. They need to pay someone to come in, someone who is qualified. No more 5 minute graduates. An established company in the area who will do what it takes to get it right.


agreed. thats why we called the guy we called. requested him specifically, locally hes the f'n man. disappointed the company sent the little engineer dude with him. would like to get the experienced guy back out WITHOUT the sidekick. ive pretty much already thrown my hands up at it. im going to try disconnecting the floats today to see if that causes any changes. but other than that im just keeping an eye out and trying to coordinate hiring out the contractors


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## mle33 (Oct 18, 2013)

mburtis said:


> One other thing. You said when the undersized wire and breakers were pointed out you attempted to compensate by adjusting the drives? Did you adjust the current limits etc or something? Do you have any documentation from initial commissioning that you could use to verify all the setting in the soft starts are the same as when the station was working properly.


i have looked and looked for such documentation. no luck. we do have an identical station across town, and i verified it matched with those. and we do not have the tripping issues over there.
we adjusted the current limit as well as played with different decel times/methods


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## mle33 (Oct 18, 2013)

my latest question probably got lost in this sea of replies.

anyone have any insight on if simply changing the contactor coil wouldve solved the whole issue on pump 2? it has behaved for almost a week now since that was done. making me wonder.


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## mle33 (Oct 18, 2013)

micromind said:


> If the water in the pit is turbulent, the new floats (if you're using them) might chatter a bit at first and at the end of the cycle.
> 
> How about disabling the floats and using only the transducer?
> 
> If the new control system is relays and no time delay, it'll cause trouble by chattering at the start and stop. Any kind of chattering will trip a breaker.


going to try this today. im leaning more and more towards that low low float getting sloshed around when they pump is right at its turn off point (as was suggested earlier in this thread). it is incredibly turbulent down there.


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## Majewski (Jan 8, 2016)

omg for my luck id use the bigger meg then smell the insulation cooking..... people would scream "JOB OPENING".


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## MikeFL (Apr 16, 2016)

Don't discount what's written in post #39. 
That man knows more about motors than I know about the back of my hand.


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## Quickservice (Apr 23, 2020)

micromind said:


> Most likely the stop ramp is set too long.
> 
> Since these are centrifugal pumps, when the stop command is given, the soft-start begins ramping the voltage down. The motor then draws more current in order to maintain speed, this current is above the breaker rating so it begins to 'ramp up' to a trip. In your case, the breaker will trip before the soft-start ramp down is complete.
> 
> *It's very likely that the trip unit in the breaker is getting weak because of all the tripping.*


There are probably a lot of electricians and engineers who don't think abou that, but I have seen that happen several times.


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## Almost Retired (Sep 14, 2021)

mle33 said:


> the control guys were asked to come back almost immediately after the problem began. they "looked over" everything and determined that this issue was not a result of anything they did or changed. we dont have a PLC guy, thats expected to be me lol. i only even learned how to utilize rockwell software (self taught entirely) last year. i barely know wtf im doing when i get into once so i dont really mess with anything. from this and several other comments, i am presenting the idea of disconnecting the floats today and hoping boss will go for it.


On a laptop in the PLC program the first thing to do is make a back up with a date time stamp. Make a log of all back ups and changes you make.
2nd you can make changes without actually changing the existing/running program. when you have looked at it long enough to be sure it is what you want, then put it in test mode.
if it works wrong, take it out of test mode, if you like how it works leave it in test mode for a few days or whatever before you make it the new program.
3rd back up that new program with a date time stamp and log it, also list why you made that change in the log.

for instance instead of removing the physical connection of the floats to the plc, put an AFI (always false instruction) in front of each float input. try them one at a time in test mode and check the results. This is instantaneously fast and saves you a lot of time and labor.

another thing to help you work in your plc is to make a print out of all outputs in the program. Make a folder to keep beside your work station. 
when motor xxx does not turn on, look up the output and begin to trouble shoot backward through the logic.

this is the absolute fastest way to find and fix a control fault. but not tripped breakers or o/l's unless they have inputs to the plc
you can even make a bypass of the faulty input in test mode (if you can run without it) until you get it fixed

this method made my life soooo much easier running a shift in a sawmill


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## mccla5214 (Mar 7, 2021)

Floats, if the controls guys are any good, you would know if you have a bad floats. The low float should be normally open (high float normally closed) and compared against the level measured by the level transmitter. If the float shows open in the PLC while the level is indicating the fluid level is above the float the PLC should be throwing a "level disagree" alarm to let you know you have an issue either with the float or the level transducer. They should be checking each other on high and low levels. The transducer should be what is normally turning the pump on and off, the floats are backup incase the transducer faults.

Based on the motor sizes you listed it sounds like your discharge piping is somewhere between 24-36 inches for a single discharge line so water hammer is a concern on start/stop. The PLC should also have a minimum restart timer so the pumps cannot be stopped and then started before the sewage has had a chance to stop surging in the discharge line. This surging can cause a trip if the pump tries to start when the surge is heading back toward the lift station.

I don't think you have a problem with breakdown in the motor power wiring. This has been going on long enough that a fault in the wiring should have resolved itself. A bad connection in a line is a different issue but I'm guessing you have checked for that from the pole to the motors. A good power monitor would help (there is a company called Accuenergy.com that sells 3 phase power meters for a very reasonable price that you can throw in a box to make yourself a cheap 3 phase power monitor. It has build in alarm logging to catch the high/low voltages/currents in addition to all the other normal stuff such as PF, KW, KVA, rotation and such. We built several of these for use in situations like this and tied them into our PLC systems for remote monitor/alarming of power related issues.

Does the HMI have an event log? We log all start/stop events along with pump failed to start and stop (yes failed to stop). The HMI/PLC system should be recording the motor currents in a trend. I programmed our PLC system to record the highest current draw during a start/run event. This value is saved on each stop so we can see how much current the motors drew during that run cycle when it trips for some reason.

Been working with VFD's and SS for over 40 years and if you are actually seeing the trip on decel only look at decel ramp time settings. SS's are a bitch about current (if it had VFD drives this would not be an issue period) at low speeds. I never set ramp times longer than 15 seconds. This is a soft-start, it's purpose is to soften start/stop issues from water hammer and incoming power surges.

The coil on the bypass contactor should NOT have been an issue in a working SS because it's purpose in life is to bypass the SCRs in the SS and remove the load from them to reduce heating that would be there if they were online all the time. That being said, with this size of motor if the contactor was dropping out and pulling in there would be surges in the motor current but they shouldn't be that high. But in replacing the coil you may have fixed an issue in the bypass contactor that was not allowing it to bypass all 3 phases when pulled it. 

You said you have an identical station, is it the same size on the motors, breakers and wiring? If so using a Fluke 87 with Min/Max record the start and stop currents on the good station and compare them to this station. Look for higher running currents that could indicate either a bearing issue or a broken bar in the motor. I can't remember from your original post if all of the pumps are having this same issue but you made a statement that stands out, "it's worked well for 5 years" and "we recently had some control work done here". I would be suspect control system just because they all started acting up when the control system was changed. Does the PLC system have a UPS battery backup system on it so the drops in line voltage on start aren't causing issues with the PLC voltage? If no UPS on the PLC power, does it have a good incoming line noise filter (SS units generate a huge amount of distoration of the incoming power during ramping)? Are all the PLC inputs/outputs relay isolated to keep electrical noise out of the PLC system? What about the PLC grounding, failure to have a good ground on the PLC grounding connection can introduce all kinds of issues into the PLC.

On the breaker trip settings if the stations are identical, the trip settings on the breakers should be the same as the good station as a start point.

The suggestion about a shunt trip on the breakers is a good one. Shunt trips can be wired to a lot of stuff (like emergency stop switches) that could be having an issue.

I feel your pain about no backup system. One of the stations here has 1200HP 4160V motors (4 of them) 80 MGD lift station and our only backup system is a gravity overflow holding pond that was intended for high incoming flow rates so we have some time before it's going to run into the creek.

I was going to say that if you needed anymore help you could message me direct since I don't always follow the board everyday but I just looked and I don't see any method of messaging direct so I will keep an eye on the board the next couple of days incase.

Mike


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## gpop (May 14, 2018)

With all the modern control crap you can add for protection its no real surprise to see a breaker trip. If you are allowed to take pics of the control panels we maybe able to guide you in the right direction.
Basically we need a lot of information that will take hundreds of written requests or we need some pictures of what you are dealing with. We have no idea if it has a shunt trip, gfci protection, phase protection or a diagnostic display. 

If you are going to figure this out you have to keep a open mind. Your opening post say that when the motor decels. Is that a true statement or is it the motor seems to trip when the station is low and the motor should be stopping. E.g the lights/panel show the motor stopping then you hear the breaker trip. 

I had a new lift station earlier this year tripping its breakers. It had run for a few months with out having a problem so that was puzzling until my partner in crime mentioned that it was probably due to higher flows as school had just started. 
Station was setup while school was out and who ever set the station up did not take into account that there would be a small voltage drop when the school re-started and the air con load dragged the voltage down ( we are bugged onto there panel ). Pumps would start and cause another 1-2 volt drop at which point the phase relay set to 210 on a 208 circuit killed the control circuit. With the pumps stopped the voltage recovered. the phase monitor self reset and the cycle would repeat until the breaker tripped.


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## mle33 (Oct 18, 2013)

mburtis said:


> Here is something stupid simple I'm sure you have already checked. This sorta goes along with the idea of verifying the controls. Have you visually watched the level in the pit through a full cycle, to verify the turn on point and the shut off point and possibly even test the low low point. Have you verified that the level sensor and/or backup floats are working as they should. I only mention this because I ram into it once on a pump station. The start float was stuck on so it would pump down till the low float shut it off but then it would kick on as soon as the shut off float came off, so it was just sitting there fluttering on and off until either the overload or the line fuses blew. Since it seems to be affecting all the pumps somewhat randomly, I would be more likely to look at something control wise or program wise, not nessasarily the motor and starters. This is of course unless you have an incoming power problem like a dropped phase or massive voltage drop or something.


we did a basic continuity test on the floats before they got installed.


Almost Retired said:


> On a laptop in the PLC program the first thing to do is make a back up with a date time stamp. Make a log of all back ups and changes you make.
> 2nd you can make changes without actually changing the existing/running program. when you have looked at it long enough to be sure it is what you want, then put it in test mode.
> if it works wrong, take it out of test mode, if you like how it works leave it in test mode for a few days or whatever before you make it the new program.
> 3rd back up that new program with a date time stamp and log it, also list why you made that change in the log.
> ...


thank you for this! i need all the tips i can get on PLC stuff


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## mle33 (Oct 18, 2013)

gpop said:


> With all the modern control crap you can add for protection its no real surprise to see a breaker trip. If you are allowed to take pics of the control panels we maybe able to guide you in the right direction.
> Basically we need a lot of information that will take hundreds of written requests or we need some pictures of what you are dealing with. We have no idea if it has a shunt trip, gfci protection, phase protection or a diagnostic display.
> 
> If you are going to figure this out you have to keep a open mind. Your opening post say that when the motor decels. Is that a true statement or is it the motor seems to trip when the station is low and the motor should be stopping. E.g the lights/panel show the motor stopping then you hear the breaker trip.
> ...


the idea of it happening during increased flow has been tossed around. but i cant find any data to back that up. im wondering if my flow meters are screwed up cause i see other stuff in that data that doesnt look right. ugh. problems on top of problems.

also, yes, im going to try to take photos today so yall arent blind trying to help me


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## mle33 (Oct 18, 2013)

MikeFL said:


> Don't discount what's written in post #39.
> That man knows more about motors than I know about the back of my hand.


roger that. going to try and pursue this as well


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## Almost Retired (Sep 14, 2021)

I am still betting on the floats being mis-wired


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## mle33 (Oct 18, 2013)

mccla5214 said:


> Floats, if the controls guys are any good, you would know if you have a bad floats. The low float should be normally open (high float normally closed) and compared against the level measured by the level transmitter. If the float shows open in the PLC while the level is indicating the fluid level is above the float the PLC should be throwing a "level disagree" alarm to let you know you have an issue either with the float or the level transducer. They should be checking each other on high and low levels. The transducer should be what is normally turning the pump on and off, the floats are backup incase the transducer faults.
> 
> Based on the motor sizes you listed it sounds like your discharge piping is somewhere between 24-36 inches for a single discharge line so water hammer is a concern on start/stop. The PLC should also have a minimum restart timer so the pumps cannot be stopped and then started before the sewage has had a chance to stop surging in the discharge line. This surging can cause a trip if the pump tries to start when the surge is heading back toward the lift station.
> 
> ...


the only testing method ive utilized for the floats is simply doing a continuity test on the leads. making sure it closes when made and is open when unmade.

i dont know much about flow/water/hydraulics but i do know that both of the identical stations feed into the same 48" force main, and ive heard the water guys complaining alot that, because the stations dont "talk" to each other or coordinate in any way, there is a big wave that slams back and forth between the stations.

yes the other station has all the exact same specs. the PLC system does have a UPS. i did compare the amps with the other station but as i said before, the only data i have is from our HMI, and it only shows an average, i cant see all 3 legs. not to mention it must only be pulling data every 1 second or longer, cause it never catches the current spike on decel. from what i CAN see though, it doesnt look like the problems motors are drawing any more than the good ones. but again the CTs that send data to the HMI arent even catching the current spikes that i see on the SS's screen.

im going to take photos today and try to investigate this shunt trip idea being talked about. i need to learn more about exactly how that works first.


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## mle33 (Oct 18, 2013)

Almost Retired said:


> I am still betting on the floats being mis-wired


mis-wired as in, out of order? or tied into the PLC wrong? im going to try and check this today or tomorrow as well. i know exactly how the floats work/tie into everything at our smaller stations. but the way the contractors did these is really confusing to me. looks more complicated than neccessary


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## mle33 (Oct 18, 2013)

gpop said:


> With all the modern control crap you can add for protection its no real surprise to see a breaker trip. If you are allowed to take pics of the control panels we maybe able to guide you in the right direction.
> Basically we need a lot of information that will take hundreds of written requests or we need some pictures of what you are dealing with. We have no idea if it has a shunt trip, gfci protection, phase protection or a diagnostic display.
> 
> If you are going to figure this out you have to keep a open mind. Your opening post say that when the motor decels. Is that a true statement or is it the motor seems to trip when the station is low and the motor should be stopping. E.g the lights/panel show the motor stopping then you hear the breaker trip.
> ...


the only reason i say it must be happening on decel is because when i view the history on the HMI, it always appears that the pump that is tripped completed its whole cycle first. the damn thing has yet to trip when im actually present though.


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## Almost Retired (Sep 14, 2021)

Yes exactly ! either or both. and if they look confusing compared to the old ones . . . the contractors were probably confused as well, another reason to suspect the floats wiring connections. are any of them paralleled or series wired? i wouldnt think they should be. again compare to a working station. Normally the floats should each have their own input to the PLC


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## Almost Retired (Sep 14, 2021)

mle33 said:


> mis-wired as in, out of order? or tied into the PLC wrong? im going to try and check this today or tomorrow as well. i know exactly how the floats work/tie into everything at our smaller stations. but the way the contractors did these is really confusing to me. looks more complicated than neccessary


Yes exactly ! either or both. and if they look confusing compared to the old ones . . . the contractors were probably confused as well, another reason to suspect the floats wiring connections. are any of them paralleled or series wired? i wouldnt think they should be. again compare to a working station. Normally the floats should each have their own input to the PLC


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## splatz (May 23, 2015)

Almost Retired said:


> I am still betting on the floats being mis-wired





mle33 said:


> mis-wired as in, out of order? or tied into the PLC wrong? im going to try and check this today or tomorrow as well. i know exactly how the floats work/tie into everything at our smaller stations. but the way the contractors did these is really confusing to me. looks more complicated than neccessary


It's not that complicated but it has to be exactly right, exactly what the PLC expects, the contractor has no leeway to get creative. 
Just curious, are the floats two wire or three wire?


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## mle33 (Oct 18, 2013)




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## Almost Retired (Sep 14, 2021)

is the 2nd pic the PLC ?


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## Almost Retired (Sep 14, 2021)

mle33 said:


> View attachment 160437
> View attachment 160438



@gpop


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## gpop (May 14, 2018)

Is the white box mounted above soft start left side a gfci relay?
Are there 2 small wires going into the breaker under the front cover for a shunt trip coil?


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## mccla5214 (Mar 7, 2021)

mle33 said:


> the only testing method ive utilized for the floats is simply doing a continuity test on the leads. making sure it closes when made and is open when unmade.
> 
> i dont know much about flow/water/hydraulics but i do know that both of the identical stations feed into the same 48" force main, and ive heard the water guys complaining alot that, because the stations dont "talk" to each other or coordinate in any way, there is a big wave that slams back and forth between the stations.
> 
> ...


I was referring to using a clamp on amp probe and comparing the start up amps on the one tripping to the ones in the other station during start a and run on all three legs. 

What the guys were talking about that's happening with the station is water hammer. That could have a contributing factor but you stated that the same configuration worked for 5 years before this time without any issues. 

Unfortunately this is going to be a lot harder to run down without a recording power analyzer so check for power issues. 

Looking at the control panel. If there is an issue it's going to be really difficult to locate. Has the system ran for over 24 hours without tripping? Do you have a heat gun to check the breakers for hot lugs or hot spots in the breaker, either of these will cause the breaker to randomly trip at different times depending on outside temperature and how long the pump has run. 

Too bad they didn't spend the money for two vfds to act as a base pumps and the other two as lag pumps on SS then you would have the water hammer issue.


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## mccla5214 (Mar 7, 2021)

mle33 said:


> the only reason i say it must be happening on decel is because when i view the history on the HMI, it always appears that the pump that is tripped completed its whole cycle first. the damn thing has yet to trip when im actually present though.


FYI if it's a decel issue have you tried making it start more often by lowering the start level so it has a faster cycle so you can see it happen? A 350 amp motor is good for around 4 starts per hour so by lowering the start level you can see it go through multiple cycles before lunch.


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## SWDweller (Dec 9, 2020)

Triac or relay contacts on the PLC? I HATE TRIAC, to many problems in the past.


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## gpop (May 14, 2018)

I believe there is a setting on the soft start that is "tbs" - time before start. That stops the motor being stopped and started which could happen due to controls problems. Can you tell us what the setting is. (if its low can you try it with 60 seconds and see what happens)


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## micromind (Aug 11, 2007)

What closes the bypass contractor in? If it's the PLC, then it'd be a big red flag. 

If this contractor gets closed during or after the ramp-down, the surge current will most likely trip the main.


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## mccla5214 (Mar 7, 2021)

micromind said:


> What closes the bypass contractor in? If it's the PLC, then it'd be a big red flag.
> 
> If this contractor gets closed during or after the ramp-down, the surge current will most likely trip the main.


This soft start controls the bypass contactor.


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## micromind (Aug 11, 2007)

mccla5214 said:


> This soft start controls the bypass contactor.


That's how it's supposed to be but I've seen engineers dumb enough to use the SS bypass contact as a PLC input and have the PLC close the contractor.........lol.


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## mccla5214 (Mar 7, 2021)

micromind said:


> That's how it's supposed to be but I've seen engineers dumb enough to use the SS bypass contact as a PLC input and have the PLC close the contractor.........lol.


Yea there's a special place in he'll for engineers


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## mle33 (Oct 18, 2013)

Almost Retired said:


> is the 2nd pic the PLC ?


yes. the floats are in the bottom center area and go to those smart relays that im not familiar with at all yet


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## mle33 (Oct 18, 2013)

gpop said:


> Is the white box mounted above soft start left side a gfci relay?
> Are there 2 small wires going into the breaker under the front cover for a shunt trip coil?


the white box is a "MAS unit" and its a relay that FLYGT apparently requires for their pumps to be covered by warranty. the go/no go relay on it is actually bypassed cause it fails really often.
the 2 wires i THINK go to the blue/yellow phase monitor thingy right behind there, but i need to double check


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## mle33 (Oct 18, 2013)

mccla5214 said:


> I was referring to using a clamp on amp probe and comparing the start up amps on the one tripping to the ones in the other station during start a and run on all three legs.
> 
> What the guys were talking about that's happening with the station is water hammer. That could have a contributing factor but you stated that the same configuration worked for 5 years before this time without any issues.
> 
> ...


we are creating a bid package for 4 VFDs as we speak. so they are moving towards solving this a different way, but it could take years. 
occasionally it will make it a whole 24 hrs with no trip.
i do have a FLIR that i could have access to, maybe i will have a look with that today.
i absolutely agree that i need some kind of monitoring device because the damn thing will NOT trip while im present. i need something i can leave hooked up for several days, i never catch it in the act


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## mle33 (Oct 18, 2013)

mccla5214 said:


> FYI if it's a decel issue have you tried making it start more often by lowering the start level so it has a faster cycle so you can see it happen? A 350 amp motor is good for around 4 starts per hour so by lowering the start level you can see it go through multiple cycles before lunch.


my boss will not let me play with any of the on/off timings. soon as we start playing with that, that "wave" in the force main gets much worse and starts slamming check valves (not sure if you saw my comment where i mention we have another identical station on the same 48" force main and have lots of issues with the water slamming back and forth in there). we have it somewhat coordinated right now and im not permitted to alter it unfortunately


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## mle33 (Oct 18, 2013)

micromind said:


> What closes the bypass contractor in? If it's the PLC, then it'd be a big red flag.
> 
> If this contractor gets closed during or after the ramp-down, the surge current will most likely trip the main.


not actually sure what opens/closes that. i assumed the PLC but i suppose i should double check.

on the "soft stop/ramp down" setting, the contactor remains closed during the ramp down.

however, when i changed it to the "freewheel/coast" to stop, the contactor opens as soon as the stop command is given. which initially made me think, problem solved, now theres no way any overcurrent could even reach the breaker to trip it.

yet, the pump i left in freehweel stop DID trip again.


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## mle33 (Oct 18, 2013)

micromind said:


> That's how it's supposed to be but I've seen engineers dumb enough to use the SS bypass contact as a PLC input and have the PLC close the contractor.........lol.


so just to be clear, i WANT the SS controlling that contactor, not the PLC?


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## mle33 (Oct 18, 2013)

gpop said:


> I believe there is a setting on the soft start that is "tbs" - time before start. That stops the motor being stopped and started which could happen due to controls problems. Can you tell us what the setting is. (if its low can you try it with 60 seconds and see what happens)


ok will check this. hopefully today. if not, will have to be monday


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## mle33 (Oct 18, 2013)

splatz said:


> It's not that complicated but it has to be exactly right, exactly what the PLC expects, the contractor has no leeway to get creative.
> Just curious, are the floats two wire or three wire?


two wire


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## splatz (May 23, 2015)

mle33 said:


> yes. the floats are in the bottom center area and go to those smart relays that im not familiar with at all yet


The plot thickens. I am curious whether they operate separately from the PLC or are they input to the PLC?


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## mle33 (Oct 18, 2013)

splatz said:


> The plot thickens. I am curious whether they operate separately from the PLC or are they input to the PLC?


i need to investigate this as well. thats kinda why i said earlier i was confused about the way this is all set up. its much more straightforward at our smaller stations, and with me being new to controls in general i am struggling. still waiting on the guys who installed all of this to provide updated drawings. i really struggle without a map


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## paulengr (Oct 8, 2017)

mle33 said:


> not sure if this is the right terminology but our check valves are "passive". meaning they just swing back and forth with the water pressure. they do have hydrauliuc cushioners but those were all serviced and according to my mechanics, all good.
> question, if what you described is the case, wouldnt the SS itself show a fault?


Yes and no. The SS that do this are known long their own power. So when you reset unless it has a fault history and it saved it, it’s gone.

No need to worry because testing for shorted SCRs is so simple and easy. You need a multimeter. The ohms range needs to be about 5 Megaohms minimum. Do not use an insulation resistance tester. There is an RC snubber or MOVs and you can trigger self commutation with a “Megger” which gives bogus readings.

With the breaker open measure each phase from line to load (L1 to T1, L2 to T2, L3 to T3). You should get at least 10K and no more than 2-3 Megaohms. The exact reading varies with age, the condition of the snubbers, if any, and make/model but most tend to be in the 250k to 1.5 megaohm range. Don’t worry if the phases don’t have the same reading. That’s common.

If high check your connections ans look for an output contactor.

Rebuilding soft starts on larger ones is easy but American manufacturers (Benshaw, Motortronics) try to stock up to 2000 HP so if time is money just buy new.


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## paulengr (Oct 8, 2017)

mccla5214 said:


> FYI if it's a decel issue have you tried making it start more often by lowering the start level so it has a faster cycle so you can see it happen? A 350 amp motor is good for around 4 starts per hour so by lowering the start level you can see it go through multiple cycles before lunch.


Not sure how you are figuring this. At 350 HP where the NEMA chart stops it’s at 3.7 for a 4 pole motor and that’s without adding soft stopping so you’d get a best maybe once every half hour, depending on how it starts and stops. The overloads will allow more often in all likelihood and it’s just easier to grab a float and lift it or short the control inputs. On continuous sensors just hold a shovel under the sensor.


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## micromind (Aug 11, 2007)

mle33 said:


> so just to be clear, i WANT the SS controlling that contactor, not the PLC?


Yes, the bypass contactor should be controlled by the SS, not the PLC.

The bypass contractor is the square one just to the right of the SS.


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## mccla5214 (Mar 7, 2021)

mle33 said:


> the white box is a "MAS unit" and its a relay that FLYGT apparently requires for their pumps to be covered by warranty. the go/no go relay on it is actually bypassed cause it fails really often.
> the 2 wires i THINK go to the blue/yellow phase monitor thingy right behind there, but i need to double check


The mas unit is the pump protection unit. Monitors the motor for moisture and overheat. This unit won't be hooked the the shunt trip unit unless someone messed up with the installation. 

Glad to hear that they are looking at the vfd units. These will save enough on electricity to pay for themselves if properly programmed. Tell your boss to check with the local power company about their rebate program for vfd units, here is Oklahoma the utility will pay up to 90 pct of the cost of the installation in rebates for switching to vfd units which may speed up the process. From what you're going to save on demand charges, energy and power factor penalties this could fast track the entire project. It's not unusual here for our clients to save over $50,000 per year on an application like yours. 

Too bad they won't let you change the start level to help find the issue but I would get out the heat gun on the breaker and see if they will let you purchase a accuenergy power monitor to build a portable power monitor.


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## paulengr (Oct 8, 2017)

Those Square D starters are miserable. Way too many extraneous parts. Some are really screwy like pneumatic timer adder decks on auxiliary contacts. I always spend twice as much time troubleshooting them.


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## gpop (May 14, 2018)

mle33 said:


> the white box is a "MAS unit" and its a relay that FLYGT apparently requires for their pumps to be covered by warranty. the go/no go relay on it is actually bypassed cause it fails really often.
> the 2 wires i THINK go to the blue/yellow phase monitor thingy right behind there, but i need to double check


In the controls you will have the hardwired permissive then the HOA switch. On the hand side that should be all that is required to give a run signal to the SS controller. On the auto side you will have any additional permissive's and the software permissive's. 

Generally anything that's deemed capable of damaging the pump is on the hardwired side so it would not be surprising to have the MAS unit, phase monitor, low level float, e-stop and soft-start fault wired there. To make life easier they normally use relays with additional contracts that can be used to signal the plc what the fault is. 

I have seen panels that have some of the hardwired faults wired directly into the shunt circuit for the breaker especially the fault circuit of the soft start and e-stop. This can be a pain as the last fault recorded by the SS will be power loss as that is the last thing it monitored just before the control circuit shut down. 

I find the external CT's in the picture interesting as i have bad memory's of the old ram-starters that had a know problem with the ct to board connector resulting in the controller seeing a motor phase imbalance and shunt tripping the breaker.


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## micromind (Aug 11, 2007)

paulengr said:


> Those Square D starters are miserable. Way too many extraneous parts. Some are really screwy like pneumatic timer adder decks on auxiliary contacts. I always spend twice as much time troubleshooting them.


No kidding!!!


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## paulengr (Oct 8, 2017)

Had a related one today (Saturday). The system is originally a gigantic 600 HP Eaton VX9000 with an auto transformer bypass starter (on a pump). The auto transformer stuff was disabled leaving just a 3 contactor bypass. The drive was retrofitted to Benshaw SG (LS). One of the CT inputs started failing on the main board so time for replacement. On power up the input contactor closed. So here is the really bad part. The output contactor is a Cutler Hammer Advantage DP contactor. That’s not only “Don’t Purchase”, it’s doubling down on it. This goofy thing is all electronic with “coil” terminals labeled 3, P, E, C. This thing was anything but obvious. I thought the interesting part was a warning in the manual not to use it around motor circuits (surges). It turns out those contacts are 3 wire start, stop, E-Stop, and neutral. The start input was wired to a VFD output contact, the stop to the VFD/bypass selector, and E-Stop is hot wired back to transformer. There are also aux contact interlocks. It took a while to trace what was going on but once we set up a run contact on the VFD it all worked.


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## mle33 (Oct 18, 2013)

gpop said:


> In the controls you will have the hardwired permissive then the HOA switch. On the hand side that should be all that is required to give a run signal to the SS controller. On the auto side you will have any additional permissive's and the software permissive's.
> 
> Generally anything that's deemed capable of damaging the pump is on the hardwired side so it would not be surprising to have the MAS unit, phase monitor, low level float, e-stop and soft-start fault wired there. To make life easier they normally use relays with additional contracts that can be used to signal the plc what the fault is.
> 
> ...


what youve said about the CTs interests me. i was in and out while they were installing all of this stuff, so did not get the whole picture, BUT i distinctly remember them having to disable a fault in their new monitoring unit because it kept showing a current imbalance (from the CTs) when there was not one in reality (according to their meter).


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## CAUSA (Apr 3, 2013)

mle33 said:


> what youve said about the CTs interests me. i was in and out while they were installing all of this stuff, so did not get the whole picture, BUT i distinctly remember them having to disable a fault in their new monitoring unit because it kept showing a current imbalance (from the CTs) when there was not one in reality (according to their meter).


I would get rid of that wiring coil that is the leads from the CT’s all that is doing is making another induction that is not required.

may not be the problem, but every ounce of prevention is worth more than a pound of cure.


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## mle33 (Oct 18, 2013)

i will mention, since all the coils for contactors were changed. not a single trip. did not trip at all last week, which is the longest period weve gone without one since this issue began. im still hesitant to call it good. maybe flow is down, or some other variable, i dont know. im just having a hard time believing it was THAT simple its not adding up to me.


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## paulengr (Oct 8, 2017)

mle33 said:


> what youve said about the CTs interests me. i was in and out while they were installing all of this stuff, so did not get the whole picture, BUT i distinctly remember them having to disable a fault in their new monitoring unit because it kept showing a current imbalance (from the CTs) when there was not one in reality (according to their meter).


You cannot just bypass this and call it a day.

On bypassed soft starts like this one there are two designs for protection and operation. On one design the CTs are connected to the soft start and it provides the overload relay function both in soft start and bypass modes. In the second design there is either an external overload relay that only operates in bypass mode or is wired into the soft start too. Especially when it’s part of the soft start you will get all kinds of problems when soft starting or stopping with a bad CT or bad input but the overload relay with a bad input can be causing your nuisance trips.

I’m trying to think of a case where I’d feel comfortable not fixing the problem. Even protection CTs are 3% accuracy on paper (always better) and still work in the 10-15% current imbalance set point.

I have a clamp on meter too. It’s OK but not good enough for this kind of problem. You need a motor analyzer or power analyzer or CT tester to measure what’s really going on.

What do the CTs connect to? If it’s the soft start itself, that is not optional and can’t just be turned off. Call 1-888-SQUARED and ask questions about if this is a good idea and then get it fixed.


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## CAUSA (Apr 3, 2013)

mle33 said:


> i will mention, since all the coils for contactors were changed. not a single trip. did not trip at all last week, which is the longest period weve gone without one since this issue began. im still hesitant to call it good. maybe flow is down, or some other variable, i dont know. im just having a hard time believing it was THAT simple its not adding up to me.


In the beginning of the string I mentioned renting a VARs meter to analyze the circuit. You can get them for long duration Data logging. Just cost. And memory.

Can you also trend the flows of the product flowing through each pump or the whole station.
I would think that this has been already done with the transducer inputs and level control. I know I would.

you have the toys to do it. May have to do some math from the trending data. But can be done.

I think the demon Is still in the shadows.


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## micromind (Aug 11, 2007)

mle33 said:


> i will mention, since all the coils for contactors were changed. not a single trip. did not trip at all last week, which is the longest period weve gone without one since this issue began. im still hesitant to call it good. maybe flow is down, or some other variable, i dont know. im just having a hard time believing it was THAT simple its not adding up to me.


This is easy for me to believe, if the contactors were chattering, there's a good chance the breaker would trip. I've seen it before though a couple of times the contactor simply exploded.


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## gpop (May 14, 2018)

mle33 said:


> i will mention, since all the coils for contactors were changed. not a single trip. did not trip at all last week, which is the longest period weve gone without one since this issue began. im still hesitant to call it good. maybe flow is down, or some other variable, i dont know. im just having a hard time believing it was THAT simple its not adding up to me.


Multiple motors probably hooked to one plc.

One daisy chained live wire and all you need is a loose connection to cause a glitch.

Change a part and tighten a screw and the problem goes away. Sometimes just moving the wires will fix the problem.

Unfortunately it was a hard job to fix when it was glitching. Now it's a even harder job to tell if it's fixed or just waiting to fail again.


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## mle33 (Oct 18, 2013)

leaving it alone for at least another week to determine if replacing the coils was the issue. will update.
i really appreciate all the help here. i have learned alot already and have more things bookmarked to research that were prompted by some of these responses. someday ill understand all this stuff lol


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## mle33 (Oct 18, 2013)

quick update. still no trips im feeling more and more confident that was it. funny enough, if youll notice in my original post i actually said "contactors and coils have been changed". i wrote this because i asked my guy to do this months ago, and he reported back to me that he had. in reality he had only changed the contacts themselves. so, i guess i couldve been on the right track all along.

unfortunately, now, the pumps are randomly getting out of order/changing their rotation. this just began, though im told no one has been playing with the controls. _sigh_


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## gpop (May 14, 2018)

mle33 said:


> quick update. still no trips im feeling more and more confident that was it. funny enough, if youll notice in my original post i actually said "contactors and coils have been changed". i wrote this because i asked my guy to do this months ago, and he reported back to me that he had. in reality he had only changed the contacts themselves. so, i guess i couldve been on the right track all along.
> 
> unfortunately, now, the pumps are randomly getting out of order/changing their rotation. this just began, though im told no one has been playing with the controls. _sigh_



Yep weird unless the reason the pumps were tripping is due to a control glitch that was cycling them and now the new coil has just enough of a residual magnetic field to allow the contractor to ride the glitch (im thinking in the millisecond range). Plc still sees the glitch as a few milliseconds is a long time when it cycling the whole program in 20 of them. So what seems random is simply the plc stepping through the run order. 
Add a event counter to the bit that steps the sequence and see if something is going on that's faster than your laptop can display it in the logic.


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## splatz (May 23, 2015)

gpop said:


> Yep weird unless the reason the pumps were tripping is due to a control glitch that was cycling them and now the new coil has just enough of a residual magnetic field to allow the contractor to ride the glitch (im thinking in the millisecond range). Plc still sees the glitch as a few milliseconds is a long time when it cycling the whole program in 20 of them. So what seems random is simply the plc stepping through the run order.
> Add a event counter to the bit that steps the sequence and see if something is going on that's faster than your laptop can display it in the logic.


I see what you're saying, makes sense to me. It would probably be nice to keep some spare coils around, since whatever caused the last to fail prematurely is probably still in the system.

I am thinking back to this


Almost Retired said:


> I agree with @gpop
> You stated the one thing that was changed just before this happened. A CONTRACTOR INSTALLED A NEW FLOAT SYSTEM. I was once told that when I heard hoof beats to think horses, _Not Zebras_. you said that station ran for 5 years as it was. think about that.


and this


mburtis said:


> The start float was stuck on so it would pump down till the low float shut it off but then it would kick on as soon as the shut off float came off, so it was just sitting there fluttering on and off until either the overload or the line fuses blew.


The floats have to be used as if they are *momentary *switches and the system (whether it's in the PLC or the relay logic) latches when the start float floats, and unlatches when the stop float hangs. If not, then when the float is right on the cusp, something is fluttering on and off as the float rides the surface. Could that be what ruined those coils?


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## gpop (May 14, 2018)

splatz said:


> The floats have to be used as if they are *momentary *switches and the system (whether it's in the PLC or the relay logic) latches when the start float floats, and unlatches when the stop float hangs. If not, then when the float is right on the cusp, something is fluttering on and off as the float rides the surface. Could that be what ruined those coils?


It doesn't even require something changing state. wastewater probably means intrinsically safe relays (not enough arse to cause a spark). Add a cheap float that's designed for AC voltage and you end up with enough resistance to be on the edge. 
Mess with the control wiring and forget to do up a screw or land on the insulation and now you have a high speed drop out.

I have spent many hours chasing problems the plc is reacting to. Things like system crashes around the same time ever night turned out to be a HPS light fitting with a bad cap and ground wire. Plc was seeing a sudden drop on the analog sensors lasting one scan and there was no logic in the program to deal with it. 
Just about all of our logic at my new job has timing code built into the function blocks to basically ignore high speed glitches.


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## Flyingsod (Jul 11, 2013)

mle33 said:


> someday ill understand all this stuff lol


NOT if you’re a _good_ electrician.


Sent from my iPhone using Tapatalk


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## mle33 (Oct 18, 2013)

im told the coils are original to the installation, almost 6 years ago. would yall still consider this premature failure of the coil?


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## gpop (May 14, 2018)

mle33 said:


> im told the coils are original to the installation, almost 6 years ago. would yall still consider this premature failure of the coil?


I can not remember ever changing a coil on a allen bradley or a abb of that size and we had over 60 of them. The screws would come loose inside the allen bradley and the mechanics would jam after 20 years on the old style if they were not serviced but generally we ran them until they were worn out and the cost to rebuild (if we could find the parts) was more expensive then replacing them with a newer style. 
The ABB were doing the same job of bypassing the softstart so they tended to last forever due to there dual contacts. 
I have never heard of a problem with Schneider contactors and the few i have worked with were over 6 years old so im going to say that 6 years would be a premature failure. I have a new mcc full of them now so i hope im correct.


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## CAUSA (Apr 3, 2013)

mle33 said:


> im told the coils are original to the installation, almost 6 years ago. would yall still consider this premature failure of the coil?


Question: what was the condition of the contacts that was replaced before the coil replacement?

-pitting.
-material corrosion?
-carbon in the arch quenching areas?

what about the Chanel’s for the assembly to slide in up and down in operation. Little to lots of play?Tightness?



I have only had 3 coils reduced in Gauss/Tesla strength in my duration in the field. All versions of sizes.

the cause was always mechanical/ heating in nature to cause the coil to change.

I would usually change the whole unit.

was any developments in the units the laminated core? Plates loose at the rivets points? Varnish erosion? Corrosion of the plates?

there has to be some reason for the change. You have 4 with the same scenario. For this to be all related to manufacturer premature failure. That is quite a lottery ticket buy day.


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## JRaef (Mar 23, 2009)

mle33 said:


> ....
> unfortunately, now, the pumps are randomly getting out of order/changing their rotation. this just began, though im told no one has been playing with the controls. _sigh_


OK, that's a new clue.
3 phase motors do not just randomly change direction. They cannot. And a Soft Start is not like a VFD that is creating the phase sequence out of a DC bus, it can only put out the phase sequence that it was given on the input.

BUT... if you have a *malfunctioning check valve or *soft starter that is single phasing or partially single phasing (one SCR is not firing, but not shorted), the LOAD can make it spin backward and once it starts doing that, the single phasing soft starter will continue it doing so. My point is, this is a clear indicator that the problem is either a bad soft starter, or as I said earlier, a check valve that is allowing back flow, or both. Would the soft starter show a fault? maybe, but if the fault trips the breaker, then the faults are reset by cycling power, the fault is cleared when you re-energize it.


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## gpop (May 14, 2018)

JRaef said:


> OK, that's a new clue.
> 3 phase motors do not just randomly change direction. They cannot. And a Soft Start is not like a VFD that is creating the phase sequence out of a DC bus, it can only put out the phase sequence that it was given on the input.
> 
> BUT... if you have a *malfunctioning check valve or *soft starter that is single phasing or partially single phasing (one SCR is not firing, but not shorted), the LOAD can make it spin backward and once it starts doing that, the single phasing soft starter will continue it doing so. My point is, this is a clear indicator that the problem is either a bad soft starter, or as I said earlier, a check valve that is allowing back flow, or both. Would the soft starter show a fault? maybe, but if the fault trips the breaker, then the faults are reset by cycling power, the fault is cleared when you re-energize it.



I presumed he meant pump rotation as the order the pumps ran in rather than the direction of the motor.
If I'm wrong that would make this even more interesting


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## micromind (Aug 11, 2007)

gpop said:


> I presumed he meant pump rotation as the order the pumps ran in rather than the direction of the motor.
> If I'm wrong that would make this even more interesting


That's what I thought too but if the motors do indeed turn backward, yes, troubleshooting takes on a whole new tangent.

As noted, it's simply not possible for a 3Ø motor to turn backward when supplied with valid 3Ø power, even if it's already turning backward when the power is applied.

If it's being single-phased, it certainly can continue in the wrong direction though its torque will be very low.

I've had more trouble with Schnider soft-starts than all other brands combined. Well, except for Cutler-Hammer........they can be trouble too.


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## mle33 (Oct 18, 2013)

CAUSA said:


> Question: what was the condition of the contacts that was replaced before the coil replacement?
> 
> -pitting.
> -material corrosion?
> ...


the contacts were very badly pittted and had alot of carbon. the entire thing has been changed.


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## mle33 (Oct 18, 2013)

micromind said:


> That's what I thought too but if the motors do indeed turn backward, yes, troubleshooting takes on a whole new tangent.
> 
> As noted, it's simply not possible for a 3Ø motor to turn backward when supplied with valid 3Ø power, even if it's already turning backward when the power is applied.
> 
> ...


yes sorry i wasnt clear, i meant the cycle / order of pumps is getting out of order. they are not turning backwards


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## mle33 (Oct 18, 2013)

JRaef said:


> OK, that's a new clue.
> 3 phase motors do not just randomly change direction. They cannot. And a Soft Start is not like a VFD that is creating the phase sequence out of a DC bus, it can only put out the phase sequence that it was given on the input.
> 
> BUT... if you have a *malfunctioning check valve or *soft starter that is single phasing or partially single phasing (one SCR is not firing, but not shorted), the LOAD can make it spin backward and once it starts doing that, the single phasing soft starter will continue it doing so. My point is, this is a clear indicator that the problem is either a bad soft starter, or as I said earlier, a check valve that is allowing back flow, or both. Would the soft starter show a fault? maybe, but if the fault trips the breaker, then the faults are reset by cycling power, the fault is cleared when you re-energize it.


sorry i meant the order/cycle of which pump is lead/lag is getting out of order. not turning backwards


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## just the cowboy (Sep 4, 2013)

Are you making a log of what is happening and what has been changed?
You are at the point of things changing and now you don't know exactly why. 
Troubleshooting is a skill of making a educated guess, making that change, note results. If not what you want put it back and move to next step. 
Rinse and repeat but note what changed and put things back if it did not fix it till you were sure it was an issue. You can end up chasing your tail if you did something in the beginning left it that way, changed something else that fixed the original problem but what you changed the first time is now the issue and you don't know it. 

Logic first.
Common sense next.
Change parts last. 
Document everything.

Good luck
Cowboy


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## paulengr (Oct 8, 2017)

just the cowboy said:


> Are you making a log of what is happening and what has been changed?
> You are at the point of things changing and now you don't know exactly why.
> Troubleshooting is a skill of making a educated guess, making that change, note results. If not what you want put it back and move to next step.
> Rinse and repeat but note what changed and put things back if it did not fix it till you were sure it was an issue. You can end up chasing your tail if you did something in the beginning left it that way, changed something else that fixed the original problem but what you changed the first time is now the issue and you don't know it.
> ...


Almost. Troubleshooting is based on the information you have at hand coming up with an explanation that fully explains the behavior. Out of the possible explanations, choose the simplest one (Ockham's razor) first and then devise a test that proves that the cause is NOT what you are guessing it is...you can't prove a negative. So you run the test and if it passes (that's not it), move on to the next test. It works, and it works every time, but it can be a very slow process.

One thing we can do to speed it up is the same thing you get in a doctor's office. There is a simple list of quick checks that we do similar to "checking vital signs". Most electricians almost reflexively check for voltage both for safety reasons and just to make sure that there is incoming power before wasting time troubleshooting something that likely isn't the problem. Checking fuses, continuity, and maybe insulation resistance are all "vital signs" type of tests. We all do the same basic tests before even getting around to troubleshooting.

The second is divide and conquer. If you have say a string of a dozen 4x4 boxes with receptacles and there is a short, do you start checking at the first box or the one in the middle?

What you don't want to do is immediately jump to conclusions. For example, a breaker trips. So does that mean that the breaker is bad? It might be bad but diagnosing breakers without a high current test set which most electricians don't have is not usually very practical. There are simple visual inspections but if it doesn't "look bad" it probably isn't. Most of the time the way most electricians "test" a circuit breaker (if they do) is by proving that something else isn't causing it to trip. Remember...we go for the simplest explanation first. If you can't find something causing it to trip (a short circuit or and overload) and especially if you can monitor current and it's within the breaker's acceptable range, only then should you replace the breaker. But many electricians consider replacing fuses and breakers as the first step to "troubleshooting" without ever actually testing anything, not even spending 10 seconds testing for resistance.

Another example and what you are hinting towards is parts changers. I'll give the simple example of a an IT "technician". If you did what they do as an electrician you'd be fired. So say some program or function on your PC crashes. What is the very first thing they do? Do they run a test or look through some configuration files or check for software versions? Heck no, the first thing they want to do is to reboot the computer! So what part of testing or inspecting or troubleshooting have they done? None. What have they changed to solve the issue and prevent further failures? Nothing. Instead they just obliterated all evidence and any chance of diagnosing the problem. Oh but wait, let's say it happens again. So what is the troubleshooting step? Why, reinstall Windows. It doesn't matter if the problem is a non-Microsoft product or has anything to do with Windows by itself. They just want to reinstall it. So this is the parts changer approach...just keep replacing things and hoping for the best. The problem is that often this may cause crashes, screw up other software, and destroys all kinds of settings and basically screws up a computer so bad it takes days to weeks to straighten everything out. In other words, 99% of IT "technicians" simply lack the most basic troubleshooting skills and have no clue whatsoever on how to troubleshoot. I mean many of these technicians have actually had some sort of school training yet are never taught anything about troubleshooting issues. I've heard every excuse in the world about why they don't do it and the most common answer is that it's "too complicated". That's an answer I expect from a teenager, not a professional that is being paid to repair computer equipment for a living. Sure there are software issues but why not at least do a base line diagnostic of the machine, maybe scan for viruses or check for software version issues? These are all checking "vital signs" for computers and even those basic skills are totally lacking. In addition I have no idea why they accept the utter crap and lack of diagnostic tools and lots of hidden code and spyware built into Windows and MacOS. That would be like Ford or GM building cars where the hood is sealed that you can't even open it to check anything on the engine. I'm not trying to advocate Linux as an extreme example of over the top diagnostic tools, just pointing out that 99% of IT "technicians" lack even basic diagnostic skills.

I'm not even against modularity and parts changing in general. Often once we determine that say a motor is defective, we change out the entire motor. Not to say that we won't get it rebuilt but somewhere someone should have done the basic assessment to verify that the problem is the motor and not say a failed gearbox.


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## gpop (May 14, 2018)

mle33 said:


> the contacts were very badly pittted and had alot of carbon. the entire thing has been changed.


With out pictures and experience with that type of contactor its hard to judge what badly burnt is . It may be a big clue as a bypass contact with a SS set to ramp and decel should be able to open and close with practically no arc. (the gates on the SS should be closed paralleling the load as the bypass contactor opens or closes)


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## mle33 (Oct 18, 2013)

just the cowboy said:


> Are you making a log of what is happening and what has been changed?
> You are at the point of things changing and now you don't know exactly why.
> Troubleshooting is a skill of making a educated guess, making that change, note results. If not what you want put it back and move to next step.
> Rinse and repeat but note what changed and put things back if it did not fix it till you were sure it was an issue. You can end up chasing your tail if you did something in the beginning left it that way, changed something else that fixed the original problem but what you changed the first time is now the issue and you don't know it.
> ...


yes i do have a notebook with the changes IM aware of. ive been doing one thing at a time, and then changing it back and trying another thing, as youve said here. problem is i think my coworker is dicking around with it too without communicating what hes done/not done properly.


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## CAUSA (Apr 3, 2013)

With the contacts being in the condition that they were in and pumps cycling out of step.

was the PLC reprogrammed for the changes that your seeing with the pumps.

has the SS auxiliary contact been confirmed to be closed when in operation? And not linked in with the PLC and previously mentioned in earlier posts?


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## micromind (Aug 11, 2007)

mle33 said:


> the contacts were very badly pittted and had alot of carbon. the entire thing has been changed.


This tells me that the contactor has been either chattering or closing/opening the locked-rotor current of the motor. 

During normal operation when the contactor closes or opens, the SS is already conducting the current and it simply takes over. No surge current. 

It would be much like controlling a resistive load.


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## Almost Retired (Sep 14, 2021)

micromind said:


> This tells me that the contactor has been either chattering or closing/opening the locked-rotor current of the motor.
> 
> During normal operation when the contactor closes or opens, the SS is already conducting the current and it simply takes over. No surge current.
> 
> It would be much like controlling a resistive load.


ah yes ..... the chattering contactor .... ? control problems ?

I get the feeling he needs a pro to look at his PLC programing


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## Almost Retired (Sep 14, 2021)

he has a probe that is supposed to be the primary control
the floats were changed, which means their _height positions_ may have also changed and they may be interfering/over riding the probe

the appearance of a change in the order of pump operation may also be the result of the same cause for the chattering contactors

I would be surprised if he does not already have a time delay on his inputs for the floats
the station ran for 5 years before they changed the floats


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## micromind (Aug 11, 2007)

It would be interesting to see what would happen if the SS was ramping down, contactor not engaged, then chatter the start input, like a float bobbing in the turbulent water. If this would cause the contactor to chatter, it would very likely trip the breaker.


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## Almost Retired (Sep 14, 2021)

micromind said:


> It would be interesting to see what would happen if the SS was ramping down, contactor not engaged, then chatter the start input, like a float bobbing in the turbulent water. If this would cause the contactor to chatter, it would very likely trip the breaker.


I suppose im wrong but i thought the start input would go to the SS not the contactor ?


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## Almost Retired (Sep 14, 2021)

and yes i agree that would trip the breaker eventually


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## CAUSA (Apr 3, 2013)

Almost Retired said:


> I suppose im wrong but i thought the start input would go to the SS not the contactor ?


Yup,
If wired and programming is correct


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## Wirenuting (Sep 12, 2010)

paulengr said:


> Troubleshooting is based on the information you have at hand.
> Out of the possible explanations, choose the simplest one (Ockham's razor) first and then devise a test that proves that the cause is NOT what you are guessing it is...you can't prove a negative.


I treat cold and unknown troublingshooting as a schrodinger's cat theory.


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## Almost Retired (Sep 14, 2021)

i agree .... loosely ...


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## gpop (May 14, 2018)

Wirenuting said:


> I treat cold and unknown troublingshooting as a schrodinger's cat theory.



Im more into the monkey, piano and beethoven 5th symphony.


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## mle33 (Oct 18, 2013)

UPDATE : just before xmas, the same contractors that made the changes at the problem station, made the same changes at the identical station across town. surprise surprise, now that station is throwing main breakers. its only happened twice (so far), but we NEVER had a problem with that station before.

to add to the confusion though, still not a single trip has occured at the original problem station since contactors and coils were changed. but, the pump run sequence is still getting itself out of order every 24 hours or so.

im now for sure convinced these contractors are to blame, though some of the incidents still dont make sense/add up, it MUST be something they did.

i think my boss is finally coming around to the idea of paying a legit engineering company to come and do a full study/report. at this point i feel this is the best option.


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## Almost Retired (Sep 14, 2021)

I refer you to post #31


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## splatz (May 23, 2015)

mle33 said:


> UPDATE : just before xmas, the same contractors that made the changes at the problem station, made the same changes at the identical station across town. surprise surprise, now that station is throwing main breakers. its only happened twice (so far), but we NEVER had a problem with that station before.


Well, FFS don't let them do any more of the same until you've figured out what they did. This (nearly) certain indication that it was their work, not a coincidental failure of contacts / coils. The failure of the contacts / coils is still a clue but it's not the problem. 

BTW, it might have been buried in here, I did not realize you had a still-working setup like the original, you should have examined and documented that one 100% before letting anyone make any changes. Hopefully you have another that's still working.


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## Almost Retired (Sep 14, 2021)

I have told him more than once to put his hands on every piece of new install and document it, then compare it to his other stations

he has said he was gonna do that, another time disconnect the new floats

apparently he has done neither, or else didnt mention it here

i think the zebras were just tooooo interesting to worry about one horse sneaking out the back gate


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## mburtis (Sep 1, 2018)

I'll play devils advocate for a min. 

1. Are the two lift stations the same age? 

My thinking is that if they are the same age, there is a possibility that there is something in the original design causing failures of the contacts and coils. The original station switching orders is a snag in this theory though. 

2. Can you go check the contacts/coils at the station that just started having problems?

If the are in really bad shape and it just started acting up that might be a sign. 

I agree that the contractors doing the same work and having the same issue is highly highly suspect... however I have burned hours troubleshooting stuff that I thought was failed because we did something over here just to find out that it was a pure coincidence that it failed at the same time. Whereas I would have found it right off if I would have looked at only what I knew. 

Did the contractors make any program changes to the PLC? 

If so

Do the contractors or you have a copy of the pre work program and the new program?

Personally I would be sitting down and going through the wiring AND the program until I understood fully what was controlling what and why. If available this would include comparing new wiring and program to the old. Your bosses might not like you "wasting" a couple of days looking at wiring and the computer though, mine wouldn't bother me. However this is how I approach it. I figure I'm not a contractor, they are going to pay me for the whole day regardless so I might as well invest the time to learn how and why the system operates. Its not JUST my job to get it back up and running, it's also my job to understand it so I can explain it and fix it next time. Because guess what the next time the pump station acts up you will be able to think about the symptoms and have a short "hit" list of most likely causes. Also it gives you the knowledge to know what stuff you should be pushing to upgrade. This is also one of the best ways to learn controls is by examining existing systems and figuring out why they are the way they are.


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## mle33 (Oct 18, 2013)

Almost Retired said:


> I have told him more than once to put his hands on every piece of new install and document it, then compare it to his other stations
> 
> he has said he was gonna do that, another time disconnect the new floats
> 
> ...


i am one electrician doing all the work for 36 lift stations, 2 wastewater plants and a water treatment plant. not to mention only being in this field for 2 years, coming from residential. this particular issue ive created this thread on is FAR from the only thing i have going on from day to day. someone simply reminded me (in another thread) that i havent updated this one in awhile. so i came and typed out what my lift station mechanics have reported to me. i have not physically even been back to this station in over a week.

i am keeping a notebook with all the suggestions here and plan on acting on them all. i apologize it hasnt been fast enough for yall lol as if i dont hear enough bitching from my bosses


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## mle33 (Oct 18, 2013)

splatz said:


> Well, FFS don't let them do any more of the same until you've figured out what they did. This (nearly) certain indication that it was their work, not a coincidental failure of contacts / coils. The failure of the contacts / coils is still a clue but it's not the problem.
> 
> BTW, it might have been buried in here, I did not realize you had a still-working setup like the original, you should have examined and documented that one 100% before letting anyone make any changes. Hopefully you have another that's still working.


i 10000% agree. unfortunately i dont get to decide, or supervise these guys work. my boss sent our outher "electrician" to document the changes they were making but he has absolutely no notes and cant answer any of my questions

i did compare everything that i had access to from the working station. ive only recently learned to even go online with a PLC so i was a bit too late to go through the programming before it got changed. not that i would even truly understand what i was looking at anyway


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## mburtis (Sep 1, 2018)

Just remember at the end of the day, water in water out is all that matters.


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## splatz (May 23, 2015)

mle33 said:


> i 10000% agree. unfortunately i dont get to decide, or supervise these guys work. my boss sent our outher "electrician" to document the changes they were making but he has absolutely no notes and cant answer any of my questions
> 
> i did compare everything that i had access to from the working station. ive only recently learned to even go online with a PLC so i was a bit too late to go through the programming before it got changed. not that i would even truly understand what i was looking at anyway


Just an aside about the PLC programming - Do the contractors touch the PLC programming? (Hopefully not, disaster if they are tinkering in there without proper documentation.) 

If the PLC programming hasn't changed, you can consider it a mystery black box and troubleshoot without knowing the programming. It couldn't hurt to know, but if it didn't change, you know that's not the problem.


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## joe-nwt (Mar 28, 2019)

splatz said:


> Just an aside about the PLC programming - Do the contractors touch the PLC programming? (Hopefully not, disaster if they are tinkering in there without proper documentation.)
> 
> If the PLC programming hasn't changed, you can consider it a mystery black box and troubleshoot without knowing the programming. It couldn't hurt to know, but if it didn't change, you know that's not the problem.


I was wondering all along if there was any "Oh, that's not right. That should be......" on a working system.


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## mburtis (Sep 1, 2018)

Be like when they upgraded our PLCs. A bunch of alarms were going off because the electricians didn't hook one whole input card up to power. So the programmer just flipped the logic in the program to shut them up and didn't say anything. It was a couple years later after an equipment pit flooded I found the problem and fixed it.


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## micromind (Aug 11, 2007)

In my mind, it's pretty much proven that the new work is the problem, the question is, what was changed from original?

It's easy to blame the contractor but if he made the modifications based on engineered drawings, I'd take a good hard look at the drawings.

The control system is not horribly complex but it's not simple. The vast majority of engineers who draw moderately complex control systems don't know diddely squat about controls, they typically rely on some sort of computer to do the design work.......not a good idea.

Here's a thought, if the SS is started by a single digital input and stopped by removing that input, I would install a time-delay relay in series with that input. If the water system can handle a start delay of more than the ramp-down time, I would set the timer to a couple of seconds longer that the ramp-down. This will ensure that the SS start signal is not chattering and causing the bypass contactor to chatter.


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## mle33 (Oct 18, 2013)

sorry for lack of updates. i promise i will not abandon this thread lol. 

i have been authorized some dedicated time next week to concentrate on this issue without being interrupted.

i have also (finally) been authorized the funds to purchase a power logger as my old one is dead. the data on the HMI is far from enough for me to see the whole picture. i am going to take action on all of the suggestions here if i am actually allowed the time as promised. im also very anxious to see the results of leaving the power logger for a week or so. i still am not 100% sure exactly when and at what amperage the breaker is tripping.

the original problem station that i made this thread about has not tripped again still, for the record.


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## Almost Retired (Sep 14, 2021)

if your original station is still switching operation order then your demon is still hiding in the shadows. it is not fixed


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## CAUSA (Apr 3, 2013)

mle33 said:


> sorry for lack of updates. i promise i will not abandon this thread lol.
> 
> i have been authorized some dedicated time next week to concentrate on this issue without being interrupted.
> 
> ...


Purchase a good Data logger. Or rent. (Short term cheaper).

they are expensive. Seen one on this site a good one fair price too. As long as licences are on the computer that goes with it.

do not know how to link it to this thread. But hopefully one of the mods can hook you up to see it.


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## mle33 (Oct 18, 2013)

Almost Retired said:


> if your original station is still switching operation order then your demon is still hiding in the shadows. it is not fixed


oh im by no means convinced its fixed. just wanted to report that it hasnt tripped again yet.


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## mle33 (Oct 18, 2013)

apologies for yet another update with no further action taken. i have another lift station and a ozone generator issue that have taken priority of my time. it never ends.

anyway, just thought id report the latest. last night we had the first trip in almost 2 weeks. im told by the night shift guy that pump 2 tripped BOTH its MCC breaker and the main feed breaker. never seen that happen before. i was not comfortable telling him to re close the breakers so i asked him to leave them off. i dont know if IM comfortable closing them. this seems strange.

the pump run order is getting out of order multiple times a day now. when it began it was once every 24 hours or so. now its 1-2x during the work day.


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## MotoGP1199 (Aug 11, 2014)

Between the existing station that started this thread and the new station that is having issues since the install I'm going to say your having an issue with the contactors cycling too quickly since they changed out the "float system". If the system cycles too quickly it could chatter, even if its just a few quick chatters it could damage the contactors contacts pre-maturely. With your old contactors the problem could show up immediately and with the new contactors with BRAND NEW contact surfaces the problem may not show up for weeks as it will take them a little longer to get damaged to the point you will draw enough current to trip a breaker.

I would look seriously hard into how the new float relays work and how they tie into the PLC. I would want to know if the contractor touched or modified the PLC programming at all. An easy test would be to just lift up some floats(if accessible) and lower them and see if there is any delay timing on the system. Try this multiple times. If the system reacts immediately each time this is most likely your issue. There has to be a buffer otherwise as water(or sewage) has waves in the pit it will try and turn on the pumps multiple times a second and cause issues.


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## paulengr (Oct 8, 2017)

Originally you said drive as in VFD. A soft start is a very different animal. And so is a double breaker trip.

Look closely at the “MCC breaker”. Chances are it’s an MCP, not a “breaker”. Most MCPs are Eaton/Cutler Hammer and say HMCP. Reason this is important is that they trip on instantaneous only. It doesn’t matter who the MCC manufacturer is. Until recently everyone used Eaton, originally due to patents.

The main breaker will be a conventional molded case circuit breaker with both thermal protection for the MCC bus and instantaneous. MCCs are rated for AIC BUT it’s only for 3 cycles (about 0.05 seconds) so they are required by Code to use instantaneous tripping. Obviously if both trip instantly on overcurrent there is a coordination problem or a defective breaker. The breaker manufacturer publishes a chart of allowable combinations of breakers. If you are outside that range or another manufacturer is involved you can get strange things including main trips but bucket doesn’t or both trip. Check this data. If it should NOT trip then you are done. Replace the bucket breaker. If you head over to NEMA.org by the way and look at NEMA AB-4 it is the standard for jnspection of ALL breakers and takes about a minute to do it. You are supposed to do this after every trip because usually right towards the end of its life the breaker will change. You will see discoloration on the exhaust ports, bubbles in the plastic, black soot marks.

If you have an HMCP it typically exhausts out the front but there are two small holes out the back that you can’t see without taking it out. I’ve seen those carbon up more than once. If you see ANY soot marks at all with this one it’s trash. Just replace.

As to the cause the fact that both breakers tripped may mean the bucket breaker itself is the issue and if you end up finding it’s bad the problem may go away once it is replaced.

As to the soft starter first determine if it is the bypass or non-bypass type. If it’s bypass and the contactor is external, open it up and check contact tips. Now get a multimeter, not a clamp meter and not a Megger and you need one with a 10 Megaohm resistance range. With it shut down test L1 to T1, L2/T2, L3/T3. You should read at least 10k and under about 2-3 Megaohms. Don’t worry if they’re different…they usually are. Outside this range the soft start is your problem. Either a snubber is going bad or an SCR. To go any further with it you’ll have to be doing component level work on the SS. I will do some of that on the big ones but they’re so cheap it’s not worth the time. You can also check the gates on the SS if you have access. The manual should tell you how.

Don’t forget the motor. Major faults in a motor pass right through a soft starter. At a bare minimum check insulation resistance (Megger), resistive unbalance, and either surge or inductive imbalance. A local motor shop should be able to do all 3 on site in about 20 minutes. If there is a fault going on intermittently this set of tests should find it. If it’s not a submersible you can also open the oeckerhead and look for any spots that are rubbing. By now it should be obvious.


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## Almost Retired (Sep 14, 2021)

MotoGP1199 said:


> Between the existing station that started this thread and the new station that is having issues since the install I'm going to say your having an issue with the contactors cycling too quickly since they changed out the "float system". If the system cycles too quickly it could chatter, even if its just a few quick chatters it could damage the contactors contacts pre-maturely. With your old contactors the problem could show up immediately and with the new contactors with BRAND NEW contact surfaces the problem may not show up for weeks as it will take them a little longer to get damaged to the point you will draw enough current to trip a breaker.
> 
> I would look seriously hard into how the new float relays work and how they tie into the PLC. I would want to know if the contractor touched or modified the PLC programming at all. An easy test would be to just lift up some floats(if accessible) and lower them and see if there is any delay timing on the system. Try this multiple times. If the system reacts immediately each time this is most likely your issue. There has to be a buffer otherwise as water(or sewage) has waves in the pit it will try and turn on the pumps multiple times a second and cause issues.


All of these things were recommended to him at the beginning of the thread. his reply was that he had other stations to look after and was not allowed the time to do these things
he brought in outside help once, maybe twice. but the help wasnt helpful for various reasons that were not his fault
his company hired a contractor to come and install the new float systems without issuing an engineering drawing of any kind
the contractor has said they will email their drawings "as soon as they can" so maybe months later
meanwhile his company is preparing to replace all of the soft starts in all of the stations
the bean counters do not understand the problem .... so they are just throwing money at it with out consulting the only electrician they have.
who has self admitted that he is not qualified or capable of figuring this out on his own

the poor man is between a rock and a hard place. i would not want to be in his position

i remember when i started at my first mill and was put on night shift by myself. at least i could call my supervisor to talk me through the things i didnt understand.


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## mburtis (Sep 1, 2018)

Just out of curiousity was the pump 2 that is tripped now, at the original station that has had the problem ongoing or is it at the second station that was just recently modified?


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## CAUSA (Apr 3, 2013)

Check your holding contactor. Contact condition. If it’s starting to pit again, that is a sure sign of chattering. 

good Luck.


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## mle33 (Oct 18, 2013)

MotoGP1199 said:


> Between the existing station that started this thread and the new station that is having issues since the install I'm going to say your having an issue with the contactors cycling too quickly since they changed out the "float system". If the system cycles too quickly it could chatter, even if its just a few quick chatters it could damage the contactors contacts pre-maturely. With your old contactors the problem could show up immediately and with the new contactors with BRAND NEW contact surfaces the problem may not show up for weeks as it will take them a little longer to get damaged to the point you will draw enough current to trip a breaker.
> 
> I would look seriously hard into how the new float relays work and how they tie into the PLC. I would want to know if the contractor touched or modified the PLC programming at all. An easy test would be to just lift up some floats(if accessible) and lower them and see if there is any delay timing on the system. Try this multiple times. If the system reacts immediately each time this is most likely your issue. There has to be a buffer otherwise as water(or sewage) has waves in the pit it will try and turn on the pumps multiple times a second and cause issues.


the only thing is, the float system is simply a backup. it only goes into "float mode" if the transducer fails. it has not been utilizing the floats at all. the only float signal that will even cause an action in regular/transducer mode is the low-low float, and my data shows the station has not gotten that low.


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## mle33 (Oct 18, 2013)

CAUSA said:


> Check your holding contactor. Contact condition. If it’s starting to pit again, that is a sure sign of chattering.
> 
> good Luck.


adding this of my list of things to do/check. if i can ever get back over there that is


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## mle33 (Oct 18, 2013)

mburtis said:


> Just out of curiousity was the pump 2 that is tripped now, at the original station that has had the problem ongoing or is it at the second station that was just recently modified?


original problem station. sorry for not clarifying.


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## mle33 (Oct 18, 2013)

any insight on how/why BOTH breakers are tripping now? is this an actual clue or just the symptoms getting worse?


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## Almost Retired (Sep 14, 2021)

mle33 said:


> the only thing is, the float system is simply a backup. it only goes into "float mode" if the transducer fails. it has not been utilizing the floats at all. the only float signal that will even cause an action in regular/transducer mode is the low-low float, and my data shows the station has not gotten that low.


are you sure that is how the EC wired it ?
not just said that he did ?
so far you have not said anyone knows exactly how the program is supposed to work
he doesnt have a drawing from your people
he doesnt have a drawing from his people

how does he know rather than guess ?????

again ...... your problems in _*TWO*_ stations did not start until the EC got involved


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## Almost Retired (Sep 14, 2021)

mle33 said:


> any insight on how/why BOTH breakers are tripping now? is this an actual clue or just the symptoms getting worse?


didnt you say they were both tripping to begin with ?


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## Almost Retired (Sep 14, 2021)

what if your co. tried a different route and (without blaming him) asked the contractor to come help them with an "unrelated" problem ?
it is quite probable that he will find and fix his mistake


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## mle33 (Oct 18, 2013)

Almost Retired said:


> didnt you say they were both tripping to begin with ?


not at the same time. it was one or the other before. 2 nights ago the guy who checks the stations reported when he got there they were both tripped.


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## mle33 (Oct 18, 2013)

Almost Retired said:


> what if your co. tried a different route and (without blaming him) asked the contractor to come help them with an "unrelated" problem ?
> it is quite probable that he will find and fix his mistake


i have actually been trying to suggest this because i feel pretty sure that if its something in the PLC i wont be able to figure it out. theyve been considering getting him back out but no solid decision yet.


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## mburtis (Sep 1, 2018)

Wasn't this the pump that had the mcc breaker replaced early on? Maybe the main is getting weak from multiple trips?


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## just the cowboy (Sep 4, 2013)

CAUSA said:


> Purchase a good Data logger. Or rent. (Short term cheaper).
> 
> they are expensive. Seen one on this site a good one fair price too. As long as licences are on the computer that goes with it.
> 
> do not know how to link it to this thread. But hopefully one of the mods can hook you up to see it.


@mle33 








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## paulengr (Oct 8, 2017)

Almost Retired said:


> All of these things were recommended to him at the beginning of the thread. his reply was that he had other stations to look after and was not allowed the time to do these things
> he brought in outside help once, maybe twice. but the help wasnt helpful for various reasons that were not his fault
> his company hired a contractor to come and install the new float systems without issuing an engineering drawing of any kind
> the contractor has said they will email their drawings "as soon as they can" so maybe months later
> ...


It’s a great learning experience (somewhat). You learn this stuff in depth when you “own” it. You learn quickly to get an attitude like a dog with a bone. Don’t let go unless they beat you off it.

When ANY controller is involved it can be a black box. For most experienced trouble shooters it is ALL black box work. It’s just that you work so long without benefit of drawings that you don’t need them. They speed things up but are not a necessity.

What impresses the hell out of electricians is once you manage to communicate to a PLC (not always easy) you can look at the interlock rung and tell in seconds why something won’t start because of inputs. Putting the same capability into an HMI screen by the way takes away this issue. But often they also like to do the software equivalent of lifting wires and jumpering things instead of fixing the hardware issue. They think it’s OK because no physical alterations were made. But it’s obviously just as bad as jumpering around/out with a wire. As a troubleshooting technique I’m all for it. As an operating practice I’m opposed to it whenever possible.


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## gpop (May 14, 2018)

Consider what controls you have and what you think they do then consider the what if's

what if.....
The pressure sensor has a glitch and fail's hi or low then recovers.
A different sensor on the same card has a glitch to ground dragging the back plane down zeroing all the channels.
A dc wire has been grounded (intentionally or un-intentionally) and now you have a short somewhere taking out the power supply momentarily.
A low level float designed to stop the pumps from running dry is glitching
plc see's a glitch on the phase monitor (that one normally happens with across the line starting causing a voltage drop so the plc stops the load which removes the voltage drop resetting the phase monitor and if program has a alarm timer it will still send a run signal repeating the problem until the breaker quits)

One of the easiest way to see what is going on is to watch the code or monitor a trend so why not ask if they have a programmer on the books that can assist you. If you have a spare analog channel also request a 4-20 ma ct (split type so you do not have to un-wire a lead) so you can monitor/trend the amps in the plc.


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## mle33 (Oct 18, 2013)

it has been decided by the powers that be, that an engineering firm will be contracted to do a full study on the station, including a hydraulic study. also our FLYGT (pump company) guy is going to evaluate all 4 motors. installing VFDs is also still on the table but wont happen anytime soon.

pump 2 AND pump 4 tripped both of their breakers (MCC and main) at the same time over the weekend. my boss asked me to "make it stop". pretty much suggesting me to do something unsafe to stop the breakers from tripping. when he saw how adamant i was about absolutely doing no such thing, and assuring him that i feel the problem is way over my head, i think he finally got the message about how serious this could be. he agreed to contract some legit folks to sort it out.

again i really appreciate all the advice here. i did try to investigate the new float system. i hand drew out everything i could trace out by just visually following wires. i also spent about an hour studying and researching the smart relays they used that i was not familiar with. by the time i got that far, i was called to another job and another and another. im still glad i did that because i learned alot, i learned alot researching the things suggested here as well. it was not for nothing.

another issue i had when i WAS able to spend time there, is, honeslty, im terrified of that station. not even 2 years ago there was a major spill resulting from this station, lawsuit ongoing. its our absolute weakest link in our entire system and it has the most flow. to top things off there is NO backup if it fails. none no bypass, no portable/standby pump to take over. so, ive been really iffy on playing with stuff i dont fully understand. at some of our smaller stations where i have a larger window of time if i screw up, im far more comfortable.

i will make sure to return to this thread to update whenever we get the problem solved. hopefully that is soon. thanks again yall


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## micromind (Aug 11, 2007)

I really appreciate the updates!


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## mburtis (Sep 1, 2018)

That is the interesting thing about water and wastewater. In a factory or something if you screw up you might shut production down and hemorrhage millions of dollars a minute. Water or wastewater of you screw up and shut something down wrong your talking wide spread public health concerns and then EPA shows up, and nobody likes EPA. For the most part it fits your typical city job that's pretty laid back, but when it goes south it can really go bad in a hurry.


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## oldsparky52 (Feb 25, 2020)

mle33 said:


> my boss asked me to "make it stop". pretty much suggesting me to do something unsafe to stop the breakers from tripping. when he saw how adamant i was about absolutely doing no such thing, and assuring him that i feel the problem is way over my head, i think he finally got the message about how serious this could be. he agreed to contract some legit folks to sort it out.


GOOD FOR YOU!!!

More people should be like this.


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