Motor overload tripping

[electro7]

Well, thanks for all the info guys. There is a lot of information to digest when I haven't been in motor work a bunch.

I think I understand some of how that mechanism works. It looks like to me that the rachet wheel will catch the pawl and cause it to open the control circuit operating the contactor. I don't understand how the heat on the element causes the rachet wheel to turn though. Either way, I see that these are installed backwards and that concerns me.

I was told it's been fine for years until recently. Now it trips, and they reset it and it works fine for a while. It may trip 3 or 4 times a day.

Not sure now, after getting all of this information, if I will continue with trying to fix this or pass it off to somebody else who is more versed in motor controls.

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[jim dungar]

Well, thanks for all the info guys. There is a lot of information to digest when I haven't been in motor work a bunch.

I think I understand some of how that mechanism works. It looks like to me that the rachet wheel will catch the pawl and cause it to open the control circuit operating the contactor. I don't understand how the heat on the element causes the rachet wheel to turn though. Either way, I see that these are installed backwards and that concerns me.

I was told it's been fine for years until recently. Now it trips, and they reset it and it works fine for a while. It may trip 3 or 4 times a day.

Not sure now, after getting all of this information, if I will continue with trying to fix this or pass it off to somebody else who is more versed in motor controls.

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The match wheel is attached to a shaft that sits inside a pool of metal similar to solder. Once the heat, primarily from the motor current, reaches a certain amount the metal softens/liquefied allowing the shaft to turn and the ratchet mechanism to operate. Once the metal cools down the shaft is again held ridigily and the ratchet mechanism to be reset.

 

[electro7]

The match wheel is attached to a shaft that sits inside a pool of metal similar to solder. Once the heat, primarily from the motor current, reaches a certain amount the metal softens/liquefied allowing the shaft to turn and the ratchet mechanism to operate. Once the metal cools down the shaft is again held ridigily and the ratchet mechanism to be reset.

Interesting, thanks!

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[retirede]

I was told it's been fine for years until recently. Now it trips, and they reset it and it works fine for a while.

Always be skeptical of what the customer tells you.

 

[electro7]

Always be skeptical of what the customer tells you.

Right

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[kwired]

Well, thanks for all the info guys. There is a lot of information to digest when I haven't been in motor work a bunch.

I think I understand some of how that mechanism works. It looks like to me that the rachet wheel will catch the pawl and cause it to open the control circuit operating the contactor. I don't understand how the heat on the element causes the rachet wheel to turn though. Either way, I see that these are installed backwards and that concerns me.

I was told it's been fine for years until recently. Now it trips, and they reset it and it works fine for a while. It may trip 3 or 4 times a day.

Not sure now, after getting all of this information, if I will continue with trying to fix this or pass it off to somebody else who is more versed in motor controls.

Sent from my SM-G998U using Tapatalk

Flip overloads over so they are installed correctly.

Verify if correct overload elements were installed in the first place, hopefully there is a selection table maybe on the backside of the enclosure cover. Select the elements that match up with motor rated current in the table.

Check motor current and verify whether it is exceeding motor nameplate rating. If it is too high, something is wrong or load is simply too much. If anyone modified something they could have ended up increasing loading on the motor.

Make sure current on all three lines is pretty equal. This type of overload doesn't detect phase loss though if current is unbalanced enough and one leg is drawing high enough it will still trip. This presumes you are dealing with a true three phase supply. If you have a phase converter supplying this you can expect some pretty severe unbalance of current at times. Air compressors is one thing that doesn't work all that great on a phase converter - other than solid state inverter type converters that do produce three equal output voltages.

 

[electro7]

Flip overloads over so they are installed correctly.

Verify if correct overload elements were installed in the first place, hopefully there is a selection table maybe on the backside of the enclosure cover. Select the elements that match up with motor rated current in the table.

Check motor current and verify whether it is exceeding motor nameplate rating. If it is too high, something is wrong or load is simply too much. If anyone modified something they could have ended up increasing loading on the motor.

Make sure current on all three lines is pretty equal. This type of overload doesn't detect phase loss though if current is unbalanced enough and one leg is drawing high enough it will still trip. This presumes you are dealing with a true three phase supply. If you have a phase converter supplying this you can expect some pretty severe unbalance of current at times. Air compressors is one thing that doesn't work all that great on a phase converter - other than solid state inverter type converters that do produce three equal output voltages.

Great, thanks!

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[hillbilly1]

Also the op mentioned high ambient temperature in the area, Square D does make heaters for high ambient temperature areas too.