DOL motors & Thermistors

[SparkyLarks]

I have a motor 4kW, DOL Start, with a Telemechanique GV2ME14 Motor Circuit Breaker.
The motor an ATEX rated Motor and is installed in ATEX Zone 2 area.
The motor manual is not clear on whether the Thermistor has to be wired if the motor is not fed from an inverter. I have emailed the manufacturer and am waiting for a response.
In a non hazardous area I would typically not use thermistor protection on a DOL Motor, but I would use a thermistor if the motor is fed by an VFD.
Similarly I would definitely use a Thermistor on a VFD fed motor in a Hazardous area.
However I am not sure if it is needed for a DOL fed motor. The fan should be more than capable of keeping the motor below the rated temperature, however if there was damage to the motor fan, or the intake was blocked it would be conceivable that the motor could heat up but the Motor protection would not trip.

 

[LionelHutz]

It doesn't have to be wired.

You may want to wire it and use the added protection for the motor.

 

[jraef]

There are separate Thermistor Tripping Relays for this situation. I'm by no means an IEC expert, but I seem to recall that maybe the Thermistor is required in some ATEX zone classifications. But don't go by me, I could be totally wrong, it may just be that IF you are going to use a Thermistor Trip Relay it too must be ATEX certified.

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[ScottyUK]

If the motor is DOL then I think it will be code compliant. If you used it with a VFD then you would require the thermistor protection to be implemented. I don't know where you are, so difficult to be more specific.


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