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UPS reporting problems with Phase Difference and Frequency

Johno12345
I have been asked to investigate a repeated occurrence in the UPS event log which is:


On battery power in response to frequency and phase difference


I have said that there isn't enough info to go by, but wondered if anyone had any pointers about what it might be? 


The only noteworthy thing that has happened here is that I have had the PFC repaired, so our PF has gone from .9 - .95 to unity.


its a large industrial site, biggest motor is 120kW
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    On battery power in response to frequency and phase difference



    I'd suggest checking the UPS manual to see if it suggests what the fancy words mean - but I suspect it could be triggered by something quite simple - perhaps such as a brief loss of one phase (one phase at 0Hz then doesn't match the others at 50Hz, likewise a constant 0V doesn't register the expected 120 degrees from the other two) - so could be a simple loose connection.


    Or it could be distortion of, or noise on, the normal sine waveforms that fool the UPS's detection electronics to think that the peaks/troughs or zero-crossing points are occurring at unexpected times. Matching the time stamp of the log messages with what else might be going on at the time might provide some clues.


      - Andy.
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  • 0

    On battery power in response to frequency and phase difference



    I'd suggest checking the UPS manual to see if it suggests what the fancy words mean - but I suspect it could be triggered by something quite simple - perhaps such as a brief loss of one phase (one phase at 0Hz then doesn't match the others at 50Hz, likewise a constant 0V doesn't register the expected 120 degrees from the other two) - so could be a simple loose connection.


    Or it could be distortion of, or noise on, the normal sine waveforms that fool the UPS's detection electronics to think that the peaks/troughs or zero-crossing points are occurring at unexpected times. Matching the time stamp of the log messages with what else might be going on at the time might provide some clues.


      - Andy.
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