Air compressor tripping on overload relay

Questions & AnswersAir compressor tripping on overload relay
Cas Staff asked 4 years ago

When we start the GA-45 Atlas cop co air compressor, it is getting tripping with indication of Motor overload, NC and not normal. what is the remedy?

4 Answers
Cas Staff answered 4 years ago


Every Atlas Copco compressor has a so-called overload relay (also called thermal relay or thermal overload relay) installed.

This relay checks the electrical current that goes to the compressor motor. When the current is too high for too long (or really high for a short time), it will trip and stop the compressor.

The thermal overload relay is like a fuse. It protects the motor and electrical wiring from overheating.

This generally happens when:

1) The compressor is mechanically broken. Check by hand if you can turn the motor/compressor (for safety, unplug the compressor/remove fuses when doing this). You should be able to turn it around by hand.

2) You have a problem with your electrical connection. Maybe 1 of the 3 phases is missing. Is the voltage still ok?

Once the overload relay tripped, you need to reset it by hand, otherwise you keep getting the same error message.

Open the electrical cabinet en press the small reset button on the overload relay.

I have included a picture of an overload relay in a (new) Atlas Copco GA37 compressor (bottom right). And another example of an overload relay. Yours will look about the same.

The RED button is a test button, press it to test if it still works (it should trip). The BLUE button is the reset button.

Many times, this overload relay can break down when it gets older and it will trip for no reason. This is a common problem. You have to replace it with a new one.

Be careful when working inside the electrical cabinet. Hire an electrician if you don’t know what you are doing.

If you do know what you are doing, you can buy thermal relays here.

Good luck! Please let me know how it works out.

Cas Staff answered 4 years ago

I experienced similar problem of my MH55 Ingersoll Rand Compressor tripping off on MTR Overld. The compressor can only be put on again after the air in the storage has been used up. This they keep doing. Am searching for the proper overload relay to replace the existing one with the hope that the problem will be over after restting it of cause.

Cas Staff answered 4 years ago

I use 4 GA250 Atlas, bt of them shutdown on motoroverload when it tries to load after offloading, I reset using the blue button. this happens only wen trying to load.

Jose Ma. answered 3 months ago

How to reset?We are experiencing motor overload trip on GA30+ we check all overload relays and not trip and found normal including the voltage but we cant still reset on the monitor. We also try to reset according to manual and it is not working.

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