TEAAC (4160 VAC) motor protection.

[AHMED0007]

Hello all,

In our plant we have medium voltage motor (4160 VAC) TEAAC, 2611KW which is the main motor and it is cooling by low voltage (480 VAC) blower motor.

The way how we run these motors as below:
-We have a logic to run the blower motor first then the main motor (2611KW) will run and if the blower motor trip or fail for any reason the main motor will trip immediately.
-If the blower motor didn't start the main motor will not start.

We have proposal to change that logic to send an alarm only if the blower motor trip or didn't start for any reason and add delay time before we trip the main motor immediately because the main motor is protected by winding RTD protection and it is set as per motor manufacturer data sheet (Alarm=150 °C / Trip=155 °C).

Is it OK to change the logic or it is better to keep as it is? What is your opinion with explanation please?

 

[LionelHutz]

I wouldn't run the motor until the RTD temperatures trip it. You can't be sure there won't be hot spots that get hot enough to cause damage by the time the RTD's trip the motor. But, you could likely get away with running it for a short while, maybe 10-30 seconds.

 

[edison123]

The existing scheme is correct, do not tamper with it. Instead, go with solving the root cause of why the blower motor fails.

Muthu

http://www.edison.co.in

 

[waross]

It is pointless to start or continue to run the large motor if the cooling fan is inoperative.
If you want better protection keep what you have and add a differential pressure switch or a sail switch to shut down the motor in the event that the cooling air becomes restricted.

Bill
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