# Troubleshoot this..............please?



## 76nemo (Aug 13, 2008)

Divide and conquer with a megger. Classic insulation failure. If it just chatters and doesn't open the OCPD, divide, megger, divide......


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## McClary’s Electrical (Feb 21, 2009)

Evan08 said:


> Okay, so I have almost completed a commercial kitchen. Now as it stands, I have 4 separate contactors sized accordingly to feed specific equipment under my range hood (gas range, tilt kettle, steamer etc). These contactors ALL have 120V coils. The coils are fed off the gas reset module which is fed from the fire suppression head. The idea is that when the fire suppression system goes off, all electrical under the perimeter of the exhaust hood shuts down.
> 
> So here is the problem that has got me stumped. I took a meter to the wires feeding the set of coils, it measures 120 volts. I then go and connect all 4 coils and then I get the circuit energized only to have all but 1 coil engage? So I then measure the voltage and I now have 100 volts. I go thru the process of elimination (check all wiring,connections, connect each coil one at a time, etc,etc). Each coil worked properly when only 1 was connected at any time. So I did find that when I only connected 1 coil, my voltage dropped down to 115 volts, then connect the second coil and measured 110 volts, then connected a third coil and measured 105 volts and of course then connected the fourth coil only to measure 100 volts. When all 4 are connected, only 3 will engage while the last one always seems to chatter.
> 
> Anyways, any help on this would be greatly appreciated. This seems like something very simple and as it should be as I have done this a hundred times before and for the life of me I can't seem to figure this one out.


 

Your control xfmr is undersized.


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## McClary’s Electrical (Feb 21, 2009)

76nemo said:


> Divide and conquer with a megger. Classic insulation failure. If it just chatters and doesn't open the OCPD, divide, megger, divide......


 

Coil chatter is a sign of a bad sign wave on control voltage, more than an overload condition on the line contacts


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## 76nemo (Aug 13, 2008)

mcclary's electrical said:


> Coil chatter is a sign of a bad sign wave on control voltage, more than an overload condition on the line contacts


 
We just talked about this a week or so ago. If the line is being dragged down under load, it very well can be an insulation failure. You're reply is obvious and well stated. I am assuming he/she wired components to spec.............


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## 76nemo (Aug 13, 2008)

"Your reply is obvious"

Rereading, that sounds pretty arrogant, sorry McClary, didn't mean that at all!!!!!!!!!


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## Evan08 (Mar 22, 2011)

There is no control transformer. The 120 volt strictly serves as control voltage on the coils for the contactors.


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## McClary’s Electrical (Feb 21, 2009)

Evan08 said:


> There is no control transformer. The 120 volt strictly serves as control voltage on the coils for the contactors.


 

then you've wired something wrong


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## Jlarson (Jun 28, 2009)

Did ya check for loose connections yet?


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## Evan08 (Mar 22, 2011)

This still doesn't explain why the control circuit voltage drops roughly 5 volts for every coil that is added to the circuit though? Am I missing something here?


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## Evan08 (Mar 22, 2011)

Wiring has been checked 3 times by 3 different journeyman. It's a very simple circuit.


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## Evan08 (Mar 22, 2011)

Yes, loose connections have been checked, everything has been checked several times.


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## McClary’s Electrical (Feb 21, 2009)

Evan08 said:


> Wiring has been checked 3 times by 3 different journeyman. It's a very simple circuit.


 

OK then, they are magic coils and are overloading the service. Quick, build a 1600 amp CT cabinet


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## K2500 (Mar 21, 2009)

Evan08 said:


> There is no control transformer. The 120 volt strictly serves as control voltage on the coils for the contactors.


Where does the 120 originate.


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## 76nemo (Aug 13, 2008)

mcclary's electrical said:


> then you've wired something wrong


 
Elaborate bro'..........gosh, this touches on a few discussions here lately. Go for it McClary............


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## lefleuron (May 22, 2010)

Wait,

Are these connected in series?


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## 76nemo (Aug 13, 2008)

Evan08 said:


> Wiring has been checked 3 times by 3 different journeyman. It's a very simple circuit.


 
And this has stumped your JW as well, or is he testing you?????


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## Evan08 (Mar 22, 2011)

120 comes off the panel, straight to a fire suppression system controller, then to the gas valve reset switch and then straight to the coils of the contactors. 120 checks out just fine at the contactors if they are disconnected from the circuit. Everything between the panel and contactors works as it should and meters out as it should as well.


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## Jlarson (Jun 28, 2009)

lefleuron said:


> Wait,
> 
> Are these connected in series?


Beat me to it, the fact the voltage seems to drop in 5 volt steps makes made me think of that.


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## Evan08 (Mar 22, 2011)

No, they are connected in parallel. This isnt a test by another co worker. It's an actual problem.


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## Shockdoc (Mar 4, 2010)

Is your microswitch operating properly ? sounds like it's failing.


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## Evan08 (Mar 22, 2011)

The whole series thing is what jumped out to me at first as well but they are in fact wired in para.


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## 76nemo (Aug 13, 2008)

Evan08 said:


> 120 comes off the panel, straight to a fire suppression system controller, then to the gas valve reset switch and then straight to the coils of the contactors. 120 checks out just fine at the contactors if they are disconnected from the circuit. Everything between the panel and contactors works as it should and meters out as it should as well.


 

"Meters out as well as it should",........sure not loaded.......


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## Evan08 (Mar 22, 2011)

Microswitch??? Not familiar with a microswitch?


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## K2500 (Mar 21, 2009)

lefleuron said:


> Wait,
> 
> Are these connected in series?


And only dropping 5v?


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## 76nemo (Aug 13, 2008)

K2500 said:


> And only dropping 5v?


 
Say 3, maybe 7............

Draw this is your head......

McClary had a point,........saying it is to spec....., draw it backwards.


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## K2500 (Mar 21, 2009)

Evan08 said:


> 120 comes off the panel, straight to a fire suppression system controller, then to the gas valve reset switch and then straight to the coils of the contactors. 120 checks out just fine at the contactors if they are disconnected from the circuit. Everything between the panel and contactors works as it should and meters out as it should as well.


Did you try bypassing the controller and/or reset switch, give 120 straight from panel?


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## Shockdoc (Mar 4, 2010)

Evan08 said:


> Microswitch??? Not familiar with a microswitch?


Micro switch is in the Ansul sysytem, they do fail sometimes leaving a weak contact, use some backwoods tools and try a 150 watt bulb on the load side of it and check voltage while on.


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## McClary’s Electrical (Feb 21, 2009)

Evan08 said:


> Microswitch??? Not familiar with a microswitch?


The Ansul system has a micro switch in it. What are powering your coils with if you're not using a microswitch?


Second thing: are you sure they are 120 volt coils?


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## lefleuron (May 22, 2010)

> Quote:
> Originally Posted by *lefleuron*
> _Wait,
> 
> ...


 Sometimes chit just pops into my head....faster then usual. Mostly its wrong, but its damn quick when it happends!:thumbup:


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## K2500 (Mar 21, 2009)

76nemo said:


> Say 3, maybe 7............
> 
> Draw this is your head......


I see a couple of switches upstream of some contactors, accurate?


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## Jlarson (Jun 28, 2009)

Here's what I'd do, with some wire or cable or cord bypass the wire from the fire system to the contractors and see what happens, that way you could rule out or find any problems with the wiring between the fire system and the contactors.

Then you could go on to hook the contactors to another 120 volt source to rule them out and also place a different load on the fire system and see if you can reproduce the voltage drop issue.


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## 76nemo (Aug 13, 2008)

K2500 said:


> I see a couple of switches upstream of some contactors, accurate?


 
True,......and new doesn't mean "proven".


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## K2500 (Mar 21, 2009)

76nemo said:


> True,......and new doesn't mean "proven".


True, I was thinking bad coil, until op said after any 3 energize.


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## lefleuron (May 22, 2010)

K2500 said:


> I see a couple of switches upstream of some contactors, accurate?


 
It was a quick shot in the dark simply because of the even steps in voltage- not knowing what could be upstream, this sounded exactly like a voltage divider. THATS where the "series" question came in.


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## mattsilkwood (Sep 21, 2008)

I think I would try eliminating the upstream switches and see what happens.


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## K2500 (Mar 21, 2009)

lefleuron said:


> It was a quick shot in the dark simply because of the even steps in voltage- not knowing what could be upstream, this sounded exactly like a voltage divider. THATS where the "series" question came in.


That response was directed at nemo's "draw it in your head". 
As others have posted, I believe it is most likely high contact resistance upstream.


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## JRaef (Mar 23, 2009)

K2500 said:


> As others have posted, I believe it is most likely high contact resistance upstream.


That's where I was heading too. Most likely a bad contact in the Ansul system or there is a tiny little set of contacts and a PC board trace that were never meant to carry a load like that and is causing the VD. We already know the coils work because he already tied them right to the 120v and they were fine. 

Put a small ice cube really in the Ansul circuit and use it as an interposing relay to drive all the other coils. I'll bet that will work.


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## miller_elex (Jan 25, 2008)

Jlarson said:


> Did ya check for loose connections yet?


What this man has, is dirty contacts upstream of the coils.

What did you say? It hits fire suppression contacts then something else?

Anyways, you can get good voltage, but low current flow because of contact failure. it causes massive voltage drops like you are seeing with negliglble loads.

EDIT: Aww sh1t, I'm late to the party, didn't see everybody else posted the same thing


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## miller_elex (Jan 25, 2008)

JRaef said:


> Put a small ice cube really in the Ansul circuit and use it as an interposing relay to drive all the other coils. I'll bet that will work.


Great advice, this will give you the ability to take on 10Amps worth of contactor coils.


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## Jlarson (Jun 28, 2009)

miller_elex said:


> What this man has, is dirty contacts upstream of the coils.


I thought about that but it sounds like a brand new system (correct me if I'm wrong Evan08) cause of this;



Evan08 said:


> Okay, so I have almost completed a commercial kitchen.


Personally I'm looking at stuff that was installed (wiring, contactors, ect) before I look at brand new fire equipment. 

Although I have found plenty of fresh from the factory equipment that was faulty it's usually after I rule out the stuff its connected to.


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## miller_elex (Jan 25, 2008)

Jlarson said:


> I thought about that but it sounds like a brand new system.


Yeah, I guess if it was a remodel there would have been alot of typos, from all the puke cloggin the keyboard.


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## Jlarson (Jun 28, 2009)

miller_elex said:


> Yeah, I guess if it was a remodel there would have been alot of typos, from all the puke cloggin the keyboard.


:laughing:


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## tufts46argled (Dec 23, 2007)

I think a diagram of the actual circuit would be very helpful. Are you sure it is parallel? And the micro switches, more than 1?


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## Evan08 (Mar 22, 2011)

There is nothing upstream of the coils. But I'm definitely going to look into this microswitch. It's coming off a "kidde" fire suppression system.


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## muck (Jun 30, 2008)

I have to agree with the microswitch theory - to much draw on the switch - u could try to put a single pole contactor ahead of the others and run the 120 thru that to the other coils but only use the microswitch to power the single pole contactor coil.


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## Evan08 (Mar 22, 2011)

Yes jlarsen , it's a brand new system. The dirty contacts now makes complete sense. I will try throwing an ice cube relay in to drive the coils tomorrow and let u know the results.


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## miller_elex (Jan 25, 2008)

If I remember... micro-switches are only good for 3 amps, at 24VAC. FAIL


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## Jlarson (Jun 28, 2009)

miller_elex said:


> If I remember... micro-switches are only good for 3 amps, at 24VAC. FAIL


If its the Kiddle system I think it is it uses a microswitch that can handle somwhere between 3 and 15 amps @ 120. I forgot the exact ratings as I haven't worked on one for a while.


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## GEORGE D (Apr 2, 2009)

I've seen them rated for around 10 @ 120 volts.


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## tufts46argled (Dec 23, 2007)

miller_elex said:


> If I remember... micro-switches are only good for 3 amps, at 24VAC. FAIL


There are line voltage micro switches, but amp load could be a reason for contact failure.


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## K2500 (Mar 21, 2009)

Is it fixed?


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## Evan08 (Mar 22, 2011)

Sorry took so long to get back on here. I threw in an ice cube relay off the microswitch to drive the coils and everything works as it should. Still a little stumped though because the rating of the microswitch was 10A 120V. Thanks for everyones help.


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## sbrn33 (Mar 15, 2007)

76nemo said:


> Divide and conquer with a megger. Classic insulation failure. If it just chatters and doesn't open the OCPD, divide, megger, divide......


You know I think this whole megger thing is so overrated. It's like it just a cool thing to say or something.
I do a **** load of service work and maybe bring my megger out a dozen time a year. Mostly for motors or underground. If you can't fix this basic problem without a megger, I think your in for a long career. 
Sorry
Scott


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## Evan08 (Mar 22, 2011)

sbrn33 said:


> You know I think this whole megger thing is so overrated. It's like it just a cool thing to say or something.
> I do a **** load of service work and maybe bring my megger out a dozen time a year. Mostly for motors or underground. If you can't fix this basic problem without a megger, I think your in for a long career.
> Sorry
> Scott


I completely agree.


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## illokano (Apr 3, 2011)

I'm kinda late answering this post but is it connected in seriers or parralel?


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## 76nemo (Aug 13, 2008)

sbrn33 said:


> You know I think this whole megger thing is so overrated. It's like it just a cool thing to say or something.
> I do a **** load of service work and maybe bring my megger out a dozen time a year. Mostly for motors or underground. If you can't fix this basic problem without a megger, I think your in for a long career.
> Sorry
> Scott


 
You're mainly overseeing construction, aren't you Scott?


I've seen handfuls of problems a megohmeter solved instantly. I have also scratched my azz over a problem a megger would of found pretty quickly when I didn't have one. I know where you're coming from. Many guys have worked the field for years getting by without one. One day they might scratch their azz going in circles when a megohmeter might fall right into play. I disagree with your statement. It sounds as if you're saying only buy an IR tester if you can afford one. I'm saying it has it's place in many scenario's. I know the topic is about service work, even so, an IR tester can save quite a few moments, and maybe a couple of headaches, that's all. To each their own.......


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## Big John (May 23, 2010)

sbrn33 said:


> You know I think this whole megger thing is so overrated. It's like it just a cool thing to say or something....


 While I agree that this particular problem doesn't sound like something I'd use a megger on, it's silly to ignore a tool just because you think it's "trendy." I can also troubleshoot a lot of things without a volt meter, but if it makes finding the solution easier, why wouldn't I use it?

There've been a lot of problems that would've taken me a good bit longer to isolate if I didn't have a megger.

-John


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## sparky105 (Sep 29, 2009)

I use my megger just as much as I use my amp clamp or muti. it is one tool in my truck that does not collect dust. the perfect tool for service work.


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## TobaSpark2085 (Apr 4, 2011)

*A different aproach*

What would happen if you swapped the chattering contactor with a non chattering contactor? does the chatter stay with the same position or the same contactor? I'm assuming that the contactors are [1] [2] [3] [4]. If the chatter stays in the same position, then the control circuit is the problem, not the contactor. I understand that the situation is resolved, but now my curiosity is picked. Are you still trying to figure it out?


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## hooch (Sep 18, 2010)

what is your wire size and the distance between?


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## rig_electricin (May 1, 2011)

Have you check amp draw as you are bring items into the circuit? Don't forget Ohms law.


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## Ellismate (Apr 8, 2011)

sparky105 said:


> I use my megger just as much as I use my amp clamp or muti. it is one tool in my truck that does not collect dust. the perfect tool for service work.


I'm interested, what all do you use it for other than motor windings etc? I just purchased one and would love to put it to more use.


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## Producer (May 29, 2011)

Shunt trip main breaker installed into a sub panel for that equipment.


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## nitro71 (Sep 17, 2009)

Evan08 said:


> Yes, loose connections have been checked, everything has been checked several times.


Well, replace the thing that doesn't work. Not that complex.


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## electricalperson (Jan 11, 2008)

sbrn33 said:


> You know I think this whole megger thing is so overrated. It's like it just a cool thing to say or something.
> I do a **** load of service work and maybe bring my megger out a dozen time a year. Mostly for motors or underground. If you can't fix this basic problem without a megger, I think your in for a long career.
> Sorry
> Scott


you obviously dont understand how to use a megger to its full potential. they are invaluable in residential and commercial troubleshooting


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## electricalperson (Jan 11, 2008)

Ellismate said:


> I'm interested, what all do you use it for other than motor windings etc? I just purchased one and would love to put it to more use.


use it to test arc fault tripping problems or GFCI tripping problems. dont forget to remove all loads including unplugging tv's lightbulbs, dimmers and other electronic devices


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## randy.wagner (Jun 21, 2011)

Don't forget to lift the lead off the breaker too.


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## eutecticalloy (Dec 12, 2010)

Jlarson said:


> Beat me to it, the fact the voltage seems to drop in 5 volt steps makes made me think of that.


Four coils in series would drop more than 5 volts per coil with 120 volt source


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## Pliersonfire (Jun 22, 2011)

What the amps on the contractor?


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## lefleuron (May 22, 2010)

The three month old troubleshooting thread that will never die.

I guess he figured it out a couple months ago.


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## eutecticalloy (Dec 12, 2010)

lefleuron said:


> The three month old troubleshooting thread that will never die.
> 
> I guess he figured it out a couple months ago.


resurrecting threads is a lot of fun.:thumbup:


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## acutter (Jun 19, 2011)

What is the wire size? It sounds like voltage drop. What is the distance from the source to the first relay. If i was a guessing man it would beat that the wire is to small.


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## Jlarson (Jun 28, 2009)

eutecticalloy said:


> Four coils in series would drop more than 5 volts per coil with 120 volt source


Yeah I don't know what I was thinking when I typed that, probably thinking 12 volt coils or some stupid **** like that for some reason :wacko: :laughing:


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