Transformers

[vmtrob]

Hows it goin
i have a question here about transformers in general. I have been repairing a CNC machine and the machine constantly comes up with an under voltage alarm. Now there are several reasons that this could be happening most of the cuases are internal to the machine. I have checked and double checked these possible faulty areas and have come up with nothing. However there is a three phase transformer that steps down the voltage before entering the machine, now there are still one or two more areas on the machine i need to check, but i was just wondering how often do transformers fail? I have never really had a problem with one before. is this a some what common problem?
No other machines on this circuit (common bus) have been having this problem.

 

[jtester]

Transformers do fail, but I've never seen the voltage slowly rise as one does. You might check your undervoltage alarm. Sometimes they are the problem and there is really no undervoltage.

Jim T

 

[beanland]

Transformers and Voltage

Transformers and Voltage

Transformers fail. Shorted windings, ground faults, open windings, loose connections. You say that you are getting a low voltage alarm. Does it happen on startup or during operation? Have you checked the service voltage to the step-down transformer? Maybe the voltage is low for some reason and the other machines tolerate the low voltage better. Utilities can legally deliver 5% low voltage. If the low-voltage alarm is set at 5% low, other events in the plant could be causing the voltage at this machine to drop. Your machine may be fine, the problem could be somewhere else. Take measurements with the machine off and operating. Check the inrush current.

 

[vmtrob]

Thanks for the help
i havefound my problem and it was not the transformer, a faulty magnetic contactor turned out to be the cuase of the problem, thanks for the suggestions though