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Mark VI "Motor Running" Message
"Motor Running" in Mark VI


I have a small question regarding the signal l52qv1a "lower case" (description of the signal: # 1A Lube oil mist separator running ).

the signal is defined in VCRC card and TBCI Board (contact input).

Now my understating is that if the signal is "1" then the contactor of the motor is closed. but does that also mean the motor is really running? what if the circuit breaker of the motor in the PEECC is open? will the signal l52qv1a still be 1?


2 out of 3 members thought this post was helpful...


By convention when l52qv1a is a logic "1" it indicates the motor #1 L.O. Mist Eliminator motor starter contactor is closed and providing power (380 VAC, or 440 VAC or 480 VAC, depending on which part of the world the unit is located) to the #1 L.O. Mist Eliminator Motor terminals. And, if everything is normal when power is applied to the motor terminals then the motor will be running. The contact which provides the status of the motor starter contactor is an auxiliary contact of the motor starter contactor, and closes when the starter contactor is energized and opens when the starter contactor is de-energized.

Unless the Motor Starter breaker is closed, there will be no power available in the control circuit of the motor starter contactor to be able to energize the contactor to close the auxiliary contact that provides the status of the contactor to the Mark VI.

Usually, when the "motor running" Process Alarm is annunciated it means the second of two redundant motors is running, when only one should be running. And, if SOEs are enabled, then when l51qv1a is a logic "1" then the presumption is that the #1 L.O. Mist Eliminator motor starter contactor is closed, applying voltage to the motor terminals, and the motor is running.

I have seen many times when an auxiliary motor was actually running--but the coupling between the motor and the device it's driving (fan; pump; etc.) is loose or has broken and the device (fan; pump; etc.) is not actually performing the function it should be.

Hope this helps!!!

2 out of 2 members thought this post was helpful...

If the circuit breaker to the motor is open, there will be no power to the control transformer and the contactor will not be able to close. I suppose if the drive shaft is seized, you could have a brief period of time where it would indicate running, until the overload trips the contactor or the circuit breaker trips on overcurrent.

Thank you CSA and Otised. That really helps!