I have a site with 7 refrigeration compressors. 6 of the compressors have a PF of .812 and 1 compressor is at .632. I am not sure why the one is so much lower. Is the PF associated to the age and wear of the compressor?
Yes, could be. I wondered whether each compressor had local pfc.Capacitor going bad?
I was going to ask the same thing. If it is a measured pf, then it could simply be that this motor is not operating near its rated capacity. The lower the load on a motor, the lower the powerfactor.Is the pf you give measured pf or that given on the nameplate?
I have a site with 7 refrigeration compressors. 6 of the compressors have a PF of .812 and 1 compressor is at .632. I am not sure why the one is so much lower. Is the PF associated to the age and wear of the compressor?
It may, but I doubt that a motor would go from 0.8 to 0.6 without some serious, or even terminal, degredation.The power factor decreases with the thermal age of the motor, in other words a motor running at half a load will be 'younger' that the one at full load after say 10000 running hours. I squared T.
It may, but I doubt that a motor would go from 0.8 to 0.6 without some serious, or even terminal, degredation.
Yes, obviously power factor varies with load.Have you looked at some of the hermetically sealed compressor PF curves? Or even regular US motor curves? At no load? If the compressor loader/unloader failed it can be just sitting there, spinning.
Yes, obviously power factor varies with load.
But my comment in post #7 was directly in response to yours about thermal aging, not loading.
I can't help thinking that might have been a more appropriate response in post #8 instead of commenting about loading. And, I didn't say that you claimed that pf would go from 0.8 to 0.6 due the thermal aging. I was just pointing out that I thought it unlikely.Except that I never claimed that power factor would go from .8 to .6 DUE to thermal aging.
That was my first thought., and IMO the first place to start looking and go from there.Capacitor going bad?
Are the motors otherwise identical?
Same rating, same voltage, same number of poles (check rpm)?
Is the pf you give measured pf or that given on the nameplate?
Are the compressors and their loading identical?
Are the motors otherwise identical?
Same rating, same voltage, same number of poles (check rpm)?
Is the pf you give measured pf or that given on the nameplate?
Are the compressors and their loading identical?
The answer is yes to all questions. The PF is measured by the ct's capturing the amperage and voltage. They are also calculating kvar.
There are no correcting capacitors.
Thanks for all the information.