Overdutied Equipment
Overdutied Equipment
(OP)
I have run into a situation where some power correction units are overdutied. The manufacturer has rated them at 10kA whereas the available fault current is around 29kA at 480V. I am thinking that I may be able to continue using these if current limiting fuses are installed upstream.
Looking for thoughts/opinions.
Thank you in advance.
Looking for thoughts/opinions.
Thank you in advance.






RE: Overdutied Equipment
If you're fusing at the cap bank location then a CLF should take care of the high fault current concern.
If you are applying the fuses upstream, then you have to pick a rating that will handle the total load. In this case, the CLF rating may be too large to protect a downstream capacitor bank.
RE: Overdutied Equipment
RE: Overdutied Equipment
RE: Overdutied Equipment
Some automatic power factor correction units come with reactors that are intended to reduce harmonics, so I wouldn't expect that adding reactors upstream of your PFC units would affect their performance.
I would also check with the manufacturer to see if there are any solutions they would recommend.
RE: Overdutied Equipment
RE: Overdutied Equipment
RE: Overdutied Equipment
Did you use the resistance of the cable or the impedance tables? The voltage drop or impedance tables include cable reactance and will yield a shorter length.
Have you looked at the impedance of a higher voltage rated cable? Higher voltage cables tend to have a higher reactance per foot due to the greater conductor spacing as a result of the thicker insulation.
This probably won't get you down enough, but if a standard rating reactor needs just a little help, you may get if from longer cables.
Bill
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"Why not the best?"
Jimmy Carter