# VFD shuts off every twelve hours without an alarm.



## T-DAWG (Jun 30, 2021)

I got an Eaton AF 9000x VFD in an eaton MCC. The motor is a 10 HP motor with a FLA of 12.2 amps running a belt driven cooling fan. At 100 % It was shutting the VFD off with a motor overtemp fault. I checked the amperage and it was pulling about 13 amps and it was also at this point that I discovered that the overloads are only able to be set up to 11 amps. Going forward with the troubleshooting I had them reduce their percentage down to 12 amps and it will run for 12 hours and then shut off without a fault code. So we are getting ready to shut the fan off for an outage and I am planning on re pitching the fan blades and replacing the overloads. I am hoping this will fix the problem because the VFD monitors the overloads and I am hoping this is causing it to turn off. I am planning on updating the 12 hour shutoff saga because so far I have not found anything that details this situation. If anyone has any information on this subject please let me know.
Thank you.


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## ElectricMatt (Dec 29, 2016)

I wools change one thing at a time instead of changing multiple factors at one time. I understand that down time is an issue. 

However, I would change the overloads first before changing the pitch on the blades. If you put the correct overload in there and continue to have the issue, then I would consider changing the pitch on the blades, depending on the flow rate you are trying to achieve. 


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## wiz1997 (Mar 30, 2021)

Is the fault a motor overtemp or is the fault a VFD overtemp?
A motor overtemp will typically involve a thermostat inside the motor.
If the motor is an air over (motor in the air stream) is there enough air flow to keep it cool?
Does the time of day figure in?

A VFD overtemp could be a result of the heat sink on the back of the drive being obstructed or the internal fan blocked or not working.


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## CAUSA (Apr 3, 2013)

What is the run signal? A basic hand off auto station with temp control.
Check run signal. Conductor. Contact blocks, pin insertion in the drive terminals. Motor termination box for loose connectors. 
The over temp fault.. On a basic pitched propeller fan, poor air flow. What changed.?
On a propeller fan, the fan laws will required more motor HP if the flow is partially blocked.

Check positioning of propeller in the axial orifice of the area that the propeller spins in. If moved from the OEM position. The extra drag, on the tip speed. Loses air flow and increases HP requirements.


I would check the Drive pulley ratio to fan ratio, before changing pitch angle. Simpler to adjust RPM then to re-position a 6 to 8 blade fan.

What is the ambient temperature of the area of the motor?

for a unit to shut off with no codes. Power interruption? Programming glitches??(rare, but plausible).

I would also call Eaton and run it by their technical department.


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## Peewee0413 (Oct 18, 2012)

Changing pitch will have virtually the same effect as reducing the frequency. Did someone increase the pitch for some reason in the past?

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## gpop (May 14, 2018)

You would have to explain your setup and where you are getting readings for better advice. 

motor over temp fault could be a sensor in the motor or a mathematical calculation inside the drive. (does the motor have a built in thermal sensor)

Amp readings with out voltage is a worthless reading. The drive output may be 13 amps but with reduced speed and a lower voltage that wouldn't be classed as a overload. If the drive can display torque percentage that would be a more useful reading.

As for the overloads that's just confusing. It sounds like a overload block on the output side of the drive which would be odd.


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## micromind (Aug 11, 2007)

Might be easier to change one of the belt pulleys.


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## micromind (Aug 11, 2007)

gpop said:


> As for the overloads that's just confusing. It sounds like a overload block on the output side of the drive which would be odd.


This is indeed odd, if the VFD has built-in O/L, I would get rid of the external one and program the VFD to protect the motor.


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## Wirenuting (Sep 12, 2010)

Are the shives grooved and worn out?
Are the belts worn and grabbing?
Are they to tight/loose and properly aligned?
Are they they correct shives as designed or a cheep adjustable type?
Are bearings on the squirrel cage worn?
Is there more grease on the blades then on McDonald’s fries?


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## Bourbon County (Aug 19, 2020)

I'm inclined to agree with Wirenuting, you need to check the mechanical components first. The overloads might just be a symptom. He pointed out most everything except the static pressure on the fan. Has anything happened to restrict air flow on either side of the fan like a damper closed or partially closed?


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## MotoGP1199 (Aug 11, 2014)

We need to see what the actual code is. Usually if a customer tells me the VFD trips on motor heat. It is actually the VFD tripping on heat due to a fan on the VFD failing. Most(not all) drives I encounter are not wired up to a motor temperature sensor. Reducing the speed on the VFD could allow it to run longer as the drive isn't producing as much internal heat.


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## SWDweller (Dec 9, 2020)

the unit is shutting down on SOMETHING. You have to find what that is. Those are a stable product and rarely have issues. Find out what the VFD is shutting down on. Checking the mechanical parts is always a good idea. Alignment is king here.

As a last shot call the local Eaton Engineering Services office and ask to speak to the drives guy. Or call the 800 number on the back of the manual. That number will take you to the tech center and they have access to all of the problems and how to fix them.

Has anyone tweaked the drive?


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## MechanicalDVR (Dec 29, 2007)

As wirenutting said check the mechanicals first.

Is there a damper that could be closing or changing the air load on the fan?


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## emtnut (Mar 1, 2015)

My understanding is that motor current goes UP if the airflow is increased, ie damper open


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## just the cowboy (Sep 4, 2013)

T-DAWG said:


> I got an Eaton AF 9000x VFD in an eaton MCC. The motor is a 10 HP motor with a FLA of 12.2 amps . I checked the amperage and it was pulling about 13 amps


You answered your own question right here. Mechanical issue


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## MechanicalDVR (Dec 29, 2007)

emtnut said:


> My understanding is that motor current goes UP if the airflow is increased, ie damper open


This is two fold, if it's closed on an air over motor the motor could be getting hotter and yes if it's open the load will increase. Just wonder if a damper position could be an issue either way?


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## micromind (Aug 11, 2007)

Another possibility is that if the VFD is controlled by some sort of contact connected to a digital input, it's possible that the contact cannot handle the extremely low current of the DI. 

Most basic switch and relay contacts will fail at some point, usually intermittently unless they are specifically designed for low current. The low current ones are usually gold bifurcated. 

I've seen this happen about a dozen times so far, usually it's a basic 10 amp relay but I've also seen it with pushbuttons. 

If this is the problem, it won't give any kind of a fault code because it's simply told to stop.


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## Bourbon County (Aug 19, 2020)

Why is this fan driven by a VFD to begin with? Is it some kind of variable air volume application or is the VFD just used to control acc and dec? What signal controls the speed, is it an air flow, or static pressure transducer? If it's a variable air flow are there any dampers or restrictions in the air stream that modulate in conjunction with blower speed?

I'm not familiar with Eaton drives, mostly just Mitsubishi and they had some screens or air filters for the onboard fan that would clog up from time to time which would cause the drive itself to overheat.


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## T-DAWG (Jun 30, 2021)

A lot of questions have been asked, First I would normally go one thing at a time but since the VFD bucket was not set up right to begin with I went ahead and changed the overloads. In order to reduce the amperage to be below the FLA 12.2 the pitch for the fan blades had to be reduced 2 degrees to fall within the amperage range. When it is shutting off now it does not represent any codes but it is like clockwork. We have two fan under cooling fans so I switched out the VFD with the other one and the symptoms remain so I am assuming the VFD is fine and I am moving on to isolating out the start circuit after the long weekend. I will be giving Eaton a call because it is still shutting off like clockwork and the operators can set their alarms to 11:30 to start it after it shuts off. The fan is driven by VFD because we are a refinery and everything needs to be at certain temps in the process so the fans are run in cascade. As of now there are no codes being sent so I guess it's back to the start. Thank you all for your input. The saga continues.


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## CAUSA (Apr 3, 2013)

T-DAWG said:


> A lot of questions have been asked, First I would normally go one thing at a time but since the VFD bucket was not set up right to begin with I went ahead and changed the overloads. In order to reduce the amperage to be below the FLA 12.2 the pitch for the fan blades had to be reduced 2 degrees to fall within the amperage range. When it is shutting off now it does not represent any codes but it is like clockwork. We have two fan under cooling fans so I switched out the VFD with the other one and the symptoms remain so I am assuming the VFD is fine and I am moving on to isolating out the start circuit after the long weekend. I will be giving Eaton a call because it is still shutting off like clockwork and the operators can set their alarms to 11:30 to start it after it shuts off. The fan is driven by VFD because we are a refinery and everything needs to be at certain temps in the process so the fans are run in cascade. As of now there are no codes being sent so I guess it's back to the start. Thank you all for your input. The saga continues.


If this is a fin fan cooling application, you might have underlying issues. With the original increase in the load. Causing you to re-pitch the blades.

Check for debris in the centre of the coil. Spot plugging from improper maintenance affects this prop loads. I know it out of the electric scope. But always fall on our shoulder to solve.

Since it’s has panel operators monitoring it , look at the temperature trending of the product, if you can. Or get them to trend it after you repair it. Sounds like your going to knock it out of the park.


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## gpop (May 14, 2018)

If its plc controls then have one of the operators video the rack a few minutes before it happens. It most probably a lost run signal.


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## just the cowboy (Sep 4, 2013)

You say it is running at 60 Hz. till you had them turn it down to get the current down. Can you temporally run it with a contactor across the line to see if issue are still there or does it only do it with VFD. If it is like clockwork something don't add up, mechanical and drive failures may happen close to repeatable times from when they startup, but don't know time issues.


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## Bourbon County (Aug 19, 2020)

The upside to the old replace parts until the problem goes away is that everyone walks away with their dignity and the knowledge that their "fix" solved the problem, not to mention the "I told you so" rights for some time. This is intangible and immeasurable.

The downside to the old replace parts until the problem goes away is that the cost of the parts, labor, and loss of production is tangible and measurable. Rest assured that the owners/managers of the facility will be measuring.


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## just the cowboy (Sep 4, 2013)

Bourbon County said:


> The downside to the old replace parts until the problem goes away is that the cost of the parts, labor, and loss of production is tangible and measurable. Rest assured that the owners/managers of the facility will be measuring.


You forgot the "did it really get fixed" part. Throwing parts may only mask the issue for awhile.


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## gpop (May 14, 2018)

some drives can be set to remain shutdown if they receive the start signal at the same time or before the stop signal clears. A small glitch will cut cause both signal to act at the same time so the drive shuts down and awaits the start signal to be removed then re-applied before starting. Simple things like a power supply being overloaded by something that starts at 11.30, Poco switching lines for night time load, etc, etc can cause this to happen.

This sounds like a simple problem rather than a gremlin but with the limited info all we can do is guess.

We have no idea if a plc is involved or if a trend of the I/O is available. Do you have a clean power supply or a 24vdc power supply. etc


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## micromind (Aug 11, 2007)

If its PLC controlled and runs 24 hours a day, I would jumper the DI at the VFD.

I would also get an ice cube relay with a pilot light and set it up as a start-stop with the PLC output in series with the stop circuit. I would use a jumper as the start switch but don't land it under a terminal, just touch it so it latches in.

This will tell whether the trouble in with the VFD or the PLC.


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## Bourbon County (Aug 19, 2020)

Another I forgot to mention: Any time you replace a component you are also introducing another possible failure mode from either installation mistake or bad part out of the box, or maybe both. Second only to exceeded life cycle, the most common failures happen at install/start-up. If you want to test this theory, install a Chinese made bearing.


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## T-DAWG (Jun 30, 2021)

So, Switching the VFD did not fix the problem as it still occurs in the same bucket. I will be checking insulation in the motor and the load filter. There is no PLC involved. I will also be calling eaton this morning to see if I can get an answer for it. I am reading your guy's responses and taking them all into account and I agree that the switching parts until it works is not the best solution but I really needed to isolate the problem to troubleshoot it past the VFD. I will keep this updated. The saga continues.


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## MoscaFibra (Apr 15, 2021)

T-DAWG said:


> So, Switching the VFD did not fix the problem as it still occurs in the same bucket. I will be checking insulation in the motor and the load filter. There is no PLC involved. I will also be calling eaton this morning to see if I can get an answer for it. I am reading your guy's responses and taking them all into account and I agree that the switching parts until it works is not the best solution but I really needed to isolate the problem to troubleshoot it past the VFD. I will keep this updated. The saga continues.


If there is no PLC where is it getting the run command from? I feel like the command running it is the problem at this point, not the VFD (based on you changing a whole new unit) Unless, you downloaded the same program from one VFD to the other, at which point it may be something in the VFD parameters (Not 100% certain with eaton that you can download / upload or if they have a runtime shut off).

What are the chances a timer is involved in the seal in circuit? I'm just curious what the controls are like, for it to happen at the EXACT same time every day is too coincidental. There is something telling the VFD to shut off if its that repeated.


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## gpop (May 14, 2018)

I think you are removing the stop signal instead of the start signal once the temp is satisfied it shuts down and will refuse to restart.


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## T-DAWG (Jun 30, 2021)

I dug into it again and found another problem. I was taking amp readings going to the motor phase A 12.2A, phase B 11.0A, phase C 11.2A. I was thinking there might be a loose connection or a bad motor winding so I checked that side over and everything is fine in the field, so back to the bucket. I started checking for voltage drops across the load filter from the motor leads that correspond to their phases starting from the bottom to the top. A1 term on the load filter to phase A to the motor 0V, A2 term to phase A to the motor 5.2V. B1 term on the load filter to phase B to the motor 4.3V, B2 to phase B to the motor 0V. C1 term on the load filter to phase C to the motor 4.4V, C2 term to phase C to the motor 0V. Phase A's readings were backwards from the other 2. I checked the buckets twin and had 0V, 6V voltage drops in order. Phase A on the load filter was wired backwards from the factory. I switched the wires and got 12 A on each phase and 0V, 6V voltage drops in order. Hopefully this fixes it, the saga continues.


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## just the cowboy (Sep 4, 2013)

I would hang LED pilot lights off of 1A, 2, 3a, referencing to X2 to check start and run commands. 1A and 2 should stay lit
And hang one from 1 to 70 and one from 1 to 38, these should stay lit unless a drive fault or ol trips.


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## gpop (May 14, 2018)

google "Rising edge required to start" then check input 8 and 9 have not been swapped.


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## micromind (Aug 11, 2007)

If you swapped buckets and the problem followed the bucket then it's not anything external, like someone hitting the estop or a power failure. 

The first thing I'd do is jumper out RO2 (24&25). If this solves it then check the programming of RO2. The output relay of most VFDs can be programmed to just about anything including a timer. 

If there is an actual fault, the VFD will stop the motor but you'll need to look at what it'll do what the fault goes away. Does the fault latch in and need to be cleared with the keypad or will it restart the motor automatically. 

It looks like TR (3&3A) are jumpered. If so then the power fail scheme is out of the picture. If it's not jumpered, look carefully at relay TR. Is it set for off-delay and what it the time set at? Most of those IDEC timers can be set to different functions. If it's not set correctly and/or if the wires are on the wrong terminals, it may very well open the power loss circuit at a specific time. It's real easy to get the function and time span settings mixed up.


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## VELOCI3 (Aug 15, 2019)

Peewee0413 said:


> Changing pitch will have virtually the same effect as reducing the frequency. Did someone increase the pitch for some reason in the past?
> 
> Sent from my SM-G998U using Tapatalk


Leave the pitch. Change the sheave if it’s belt drive


Sent from my iPad using Tapatalk


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## T-DAWG (Jun 30, 2021)

micromind said:


> If you swapped buckets and the problem followed the bucket then it's not anything external, like someone hitting the estop or a power failure.
> 
> The first thing I'd do is jumper out RO2 (24&25). If this solves it then check the programming of RO2. The output relay of most VFDs can be programmed to just about anything including a timer.
> 
> ...


It quit again, I was thinking along the same lines as this to move forward. I honestly didn't think of switching the buckets but that would be a good place to separate the bucket and the external wiring. Thank you.


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## T-DAWG (Jun 30, 2021)

just the cowboy said:


> I would hang LED pilot lights off of 1A, 2, 3a, referencing to X2 to check start and run commands. 1A and 2 should stay lit
> And hang one from 1 to 70 and one from 1 to 38, these should stay lit unless a drive fault or ol trips.


I could do this overnight with a camera setup after I separate the bucket and the external wiring. Thank you.


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## T-DAWG (Jun 30, 2021)

The problem followed the bucket. I installed the jumper between 24 and 25 to hopefully eliminate the drive shutting it off. I transferred all the relays over to the twin. If one shuts off then I need to look closer at the relays if the other shuts off I need to look into the overload contact and if neither shut off then it is the VFD shutting it off for some reason. Getting it narrowed down, more fun, the saga continues.


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## gpop (May 14, 2018)

2 simple questions could make this so much easier as i do not see any field wiring.

What does the vfd screen say when it stops. (stopped/not enabled/etc)
and how does the operator restart it. (does he have to press the stop button, reboot the panel or simply press the start button)


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## CAUSA (Apr 3, 2013)

To help in the relay diagnostics. And Mgmt will not produce a PO for led lamps. That I have done in the past.

if you have access to tattle tails for high current or make your own for low current. Use a fuse holder (see through or open). With a low currant fuse in a pinch to see what relay/ contact has opened.

note. It is easy for higher current circuits for this trick, but tricky at the lower current signal circuits. Need very low current fuses 1/32A or lower. Enough to blow when the relay contacts opens. But not to blow when the contacts are closed. Also test it to see that it will blow when contact is opened. I have also put in toggle switch to keep fuse from blowing when system is starting. This keeps false testing to a minimum. Then close the switch on the contact that I wish to test.

Note: looks like a rats nest but, some times nessesary on intermittent or unmanned faults. It helps me look in the right direction when all else fails.

CR1 is one area I would go stampeding to. I cannot see the relay terminal numbers, but 24v out to 8 and 9 run signal/Isolation is a good start. This will cover the runstop signal and the isolation signal.

Hope this helps


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## T-DAWG (Jun 30, 2021)

gpop said:


> 2 simple questions could make this so much easier as i do not see any field wiring.
> 
> What does the vfd screen say when it stops. (stopped/not enabled/etc)
> and how does the operator restart it. (does he have to press the stop button, reboot the panel or simply press the start button)


It just acts like someone pressed the stop button with no code. They just press the start button to start it which is what is holding me to the start circuit ladder. I will know more when I get back on shift. The weird thing is the time but it could just be a weak coil that lasts that exact time or a coincidence. It is getting narrowed down.


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## gpop (May 14, 2018)

No field wiring equals no plc alarm so how do the operators know its the same time. The fan may stop earlier and its only spotted when the temp starts to rise or when they do there rounds at a set time.


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## just the cowboy (Sep 4, 2013)

CAUSA said:


> To help in the relay diagnostics. And Mgmt will not produce a PO for led lamps. That I have done in the past.
> 
> if you have access to tattle tails for high current or make your own for low current. Use a fuse holder (see through or open). With a low currant fuse in a pinch to see what relay/ contact has opened.
> 
> ...


That was the way I did it for years on old relay logic, with fuses I have posted it before. Now a Click PLC and a some logic will give me that information. It is good to see some old school ideas come back out and get passed along.

Cowboy


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## T-DAWG (Jun 30, 2021)

gpop said:


> No field wiring equals no plc alarm so how do the operators know its the same time. The fan may stop earlier and its only spotted when the temp starts to rise or when they do there rounds at a set time.


For a little bit I thought the operators were messing with me. We have an Emerson delta v distributed control system that logs the time kind of like a plc with a scada system and it is pretty spot on with the time. The field wiring is shown in the dotted boxes in the schematic/ladder diagram.


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## T-DAWG (Jun 30, 2021)

Update, the problem is gone for now which leads me to believe that me jumping the vfd fault relay confirms the vfd is turning it off. When I called Eaton they said they had never heard of anything like it. I still could be wrong so at the next available opportunity I will remove the jumper to see if the problem comes back. Meanwhile since I switched VFD's I noticed I did not switch the keypad with it the first time and I wonder if it might be the keypad causing the issue. I still appreciate all the help and I understand that there is a lack of information on my part and I will keep doing my best to keep responding and updating. the saga continues.


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## T-DAWG (Jun 30, 2021)

The fan started doing the same thing after removing the jumper so I changed the only thing left associated with the VFD that I didn't change yet, THE KEYPAD. The fan is working and hasn't shut off in 7 days or so. I am both relieved and frustrated about this whole thing because I didn't switch the keypad with it earlier and that would have eliminated a week or so of troubleshooting. I hope this helps someone in the future so they don't have to go through the same confusion as I did. Thank you all for the help. The saga has ended.


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## gpop (May 14, 2018)

T-DAWG said:


> The fan started doing the same thing after removing the jumper so I changed the only thing left associated with the VFD that I didn't change yet, THE KEYPAD. The fan is working and hasn't shut off in 7 days or so. I am both relieved and frustrated about this whole thing because I didn't switch the keypad with it earlier and that would have eliminated a week or so of troubleshooting. I hope this helps someone in the future so they don't have to go through the same confusion as I did. Thank you all for the help. The saga has ended.



Hindsight is 20/20

This could have been as simple as looking at the vfd alarm log.

The panel drawing is odd because someone decided to add a vfd fault contact to break the run latch. That seems like a good idea until someone comes up with the cleaver idea of using the auto reset command in the drive.
Now you have a drive trip, Run latch is broken, Vfd resets and you have no idea what happened except it stopped and will restart when the button is pressed.

If someone would have added a time delay to the RO2 that was 1 second longer than the auto reset time the drive would reset until it reached the reset count then stopped on a reset alarm. In that case a small glitch like panel loss may have never been detected as the drive would have reset with out losing the run latch.

If the auto reset was disabled the drive would have tripped and stayed tripped. The operator would have had to reset the drive before pressing start and you would have been able to check the fault number.

Im still not sure the keypad was the problem based on past experience (sounds way to much like a high dc buss voltage problem caused by a spike). Simply pulling up the alarm log should prove you was correct.

Anyway i suggest you think about either disabling auto reset or adding a time delay to RO2 to prevent something like this in the future.


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## wiz1997 (Mar 30, 2021)

When you replaced the VFD did you use the same keypad?

Parameters may be stored in the keypad and even though you installed a new VFD the keypad will load the parameters it has into the VFD during power up.

Some drives I've worked on will ask you to confirm downloading the parameters from the keypad, others will just do it on power up.

Since you still have the issue even with a new drive, I think I would look into the keypad parameters.


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