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Discussion Starter · #1 ·
I have a cabinet full of the 140M-C2E motor starters ranging from B10 to B25. Sometimes when a starter trips it will not allow itself to be reset even after turning completely off. It will turn to the on position but not latch. Eventually after a minute or two it will close so i don't know if it's a time out feature or what. I read through all the literature I could find on them but nothing is mentioned. Any help would be appreciated
 

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Discussion Starter · #4 ·
erics37 said:
Give it the ol' Fonz.
Naturally that was my first method. There's 80 of these buggers in the cabinet and it happens randomly to random starters
 

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Naturally that was my first method. There's 80 of these buggers in the cabinet and it happens randomly to random starters
Not too familiar with AB stuff. Is it an MMS? I've found that those can be...... weird...... when it comes to operating/resetting them.

Are yours tripping for legitimate reasons like overload? Maybe you're right; they probably have to cool off a bit or something in order to reset them.
 

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Those starters very likely have a time delay for O/L reset. Here's why.....

If a motor is overloaded enough that it trips the starter, then the motor is very close to its maximum insulation temperature. If the starter allowed an instant O/L reset, the motor would still be hot. If there's a time delay, the motor will cool......well, somewhat anyway.....
 

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Discussion Starter · #9 ·
micromind said:
Those starters very likely have a time delay for O/L reset. Here's why..... If a motor is overloaded enough that it trips the starter, then the motor is very close to its maximum insulation temperature. If the starter allowed an instant O/L reset, the motor would still be hot. If there's a time delay, the motor will cool......well, somewhat anyway.....
Thanks for the info. I haven't given this issue my full attention yet but I can't imagine why any of these motors would be running overloaded. They are for a conveyor that runs off and on for 10 hours a day and when they start tripping there is no obvious pattern in what's been reported to me.

My thought is maybe they are grouped too tight in the cabinet. There are three rows of 25~ starters mounted on a buss rail and they are virtually touching each other from left to right. I also wonder if a thermal scan might turn up something even though physically nothing feels hot to touch
 

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Discussion Starter · #10 ·

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Thanks for the info. I haven't given this issue my full attention yet but I can't imagine why any of these motors would be running overloaded. They are for a conveyor that runs off and on for 10 hours a day and when they start tripping there is no obvious pattern in what's been reported to me.

My thought is maybe they are grouped too tight in the cabinet. There are three rows of 25~ starters mounted on a buss rail and they are virtually touching each other from left to right. I also wonder if a thermal scan might turn up something even though physically nothing feels hot to touch
They are made to be next to each other, AB sells feeder buss to link a bunch of them together side by side. I've used quite a few of these manual motor protectors and haven't had any issues. I've never had a problem resetting them after they've tripped but usually when I show up on site it's been a while since it's happened.

I would start by amping and megging the motors with issues. Have you verified motor nameplate current matches the dial setting?

Maybe it'd be worth it to put some colored stickers on the ones you're having trouble with to see if it's the same ones tripping over and over again.
 

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Thanks for the info. I haven't given this issue my full attention yet but I can't imagine why any of these motors would be running overloaded. They are for a conveyor that runs off and on for 10 hours a day and when they start tripping there is no obvious pattern in what's been reported to me.

My thought is maybe they are grouped too tight in the cabinet. There are three rows of 25~ starters mounted on a buss rail and they are virtually touching each other from left to right. I also wonder if a thermal scan might turn up something even though physically nothing feels hot to touch


thats what im thinking, to much heat.... replace them all with telemecanique or put in some axiual? fans. one on the top right for negative preasure and one on the bottom left for pausitive.
 

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the reason i say telemecanique is because ive built mcc's with them side by side anywhere from 80 to 300 starters in a cabinet and never had an issue. yet ive replaced AB's stuff for this same problem your having.
 

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I would buy A - B before Telemecanique any day of the week. Thermal scan is in order.
 

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ALL thermal overload protective devices, as those are, are REQUIRED to take time to reset. The time is carefully chosen by virtue of the bi-metal strip materials in an attempt to approximate the thermal cool-down constant of the motor, meaning the rate at which the motor will cool down based on standard design conditions.

The difference between A-B and Tele in that respect would be that Tele, being a French company, bases their design on IEC motors, which have NO service factor and require fast tripping OLs set at class 10 or lower. That means the motors tripped a lot sooner, therefore they are not as hot and cool off faster. A-B on the other hand, being a North American company, bases the reset time on NEMA motor designs, which allow for a 1.15 service factor and a class 20 trip. So yes, the AB versions will take longer to reset, but that's because it held in a lot longer and the motor got a lot hotter. The Tele versions will trip more often if using a NEMA motor, or to look at it the other way, the Tele will not allow you to take advantage of the added thermal capacity of a NEMA motor.

The AB units are OK with "zero stacking" meaning mounting right next to each other. But ALL bi-metal OL devices are susceptible to high ambient heat inside the box. The trip times are based on the device being in a 25C environment, and have automatic compensation to adjust themselves for up to 40C (104F). But after that, all bets are off. Each unit gives off about 9 watts of heat, so if you have dozens of them in a box, it all adds up. So if you are POSITIVE that the motors are not really being overloaded, then it's likely a cumulative heat problem in your enclosure.
 

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... The time is carefully chosen by virtue of the bi-metal strip materials in an attempt to approximate the thermal cool-down constant of the motor, meaning the rate at which the motor will cool down based on standard design conditions. ...
How do they make that work given the huge difference in mass between the bi-metal strip and the motor windings?

It has been my experience that overload relays with the bi-metal strips can be reset almost instantly. The melting alloy types can't be.
 

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Somewhere I have video of a 50HP motor with smoke just rolling out of it because the operators kept hitting the damn reset every couple minutes when it went out on OL. There is a delay in those bimetallics, but it doesn't come anywhere near to accurately representing the thermal mass of the motor.

Those combination AB starters are bimetallic, so I agree that's also very likely your problem.
 

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Discussion Starter · #18 ·
I confirmed my suspicion this morning that this wasn't an overload issue but a thermal issue contained to the problematic starters. I hit the cabinet with a thermal imager this morning and immediately found the impaired connections. It's never been my habit to check the hundreds of panel shop terminations for proper torque but it would've saved us a headache for sure. It took me over an hour to check the rest of the feeder terminals.
 

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How do they make that work given the huge difference in mass between the bi-metal strip and the motor windings?

It has been my experience that overload relays with the bi-metal strips can be reset almost instantly. The melting alloy types can't be.
Somewhere I have video of a 50HP motor with smoke just rolling out of it because the operators kept hitting the damn reset every couple minutes when it went out on OL. There is a delay in those bimetallics, but it doesn't come anywhere near to accurately representing the thermal mass of the motor.

Those combination AB starters are bimetallic, so I agree that's also very likely your problem.
The bi-metal design is SUPPOSED to match the thermal time constant of a typical motor. But not all OL relays are created equal. Cheap ones are designed to be cheap, good ones are designed to be good. When I worked as a Product Manager for a company developing a soft starters with an integral bypass that needed a stand-alone OL relay, we tested every one of the major manufacturers to look at reliability, repeatability and sensitivity. I was amazed at how much variation there was. A LOT of the IEC bi-metal OL relays tripped WAY sooner than they needed to. Class 10 says 10 seconds at 600% current, some were as short as 3 seconds but technically that satisfies the requirement, which only says no MORE than 10 seconds. When that is the case it's a nuisance but it would in theory be able to be reset faster. The design spec also calls for trip and reset just once. So after the second trip, all bets are off. Remember, most of the time a motor runs UNDER it's FLA rating and if the OL trips, it's usually because it really is overloaded. But nothing can be made idiot proof, and constantly resetting while doing nothing to fix the overloading problem is right on Webster's page defining "idiot".

After that eye opening experience though, I ONLY use solid state overload relays now unless there is no other choice. No thermal issues to deal with.
 

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Sounds like someone should give you an atta-boy. So here's one from me, :thumbsup:

Please don't take this as sarcasm or condescension, it's sincere. :)
 
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