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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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  • Former Community Member
    0 Former Community Member
    We had this problem on a little UPS several years ago

    The Grid is obliged to maintain frequency between 49.5 and 50.5Hz (although apparently it usually does much better than that)

    The UPS supplier had set the allowable limits much tighter than the routine variation in frequency, so we had the same problem

    We just widened the limits to the Grid's maximum spec and everything was OK

    You could check the manuals but much PLC and IT equipment that I've worked with is designed to work over the full range of 50 to 60Hz (and a wide range of voltages) so IMHO I would expect that most up-to-date equipment should tolerate a reasonable frequency swing.

    Hope this helps

    Ian
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  • Former Community Member
    0 Former Community Member
    We had this problem on a little UPS several years ago

    The Grid is obliged to maintain frequency between 49.5 and 50.5Hz (although apparently it usually does much better than that)

    The UPS supplier had set the allowable limits much tighter than the routine variation in frequency, so we had the same problem

    We just widened the limits to the Grid's maximum spec and everything was OK

    You could check the manuals but much PLC and IT equipment that I've worked with is designed to work over the full range of 50 to 60Hz (and a wide range of voltages) so IMHO I would expect that most up-to-date equipment should tolerate a reasonable frequency swing.

    Hope this helps

    Ian
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