PF Correction

[markiec]

We're interested in eliminating the losses in our distribution system that are created by reactive (and harmonic) currents. Fortunately or unfortunately as the case may be, fixed capacitors were installed some time ago at our main service entrance to eliminate/minimize the power factor penalty from the utility company. That's proven effective in eliminating the penalty and fixing the utility's problem, but we'd still like to reduce our "inside" losses. Are there any concerns with installing static capacitance AT our 480 VAC inductive motor loads to further cancel out the inductive current and reduce our losses? Thanks in advance for the feedback.

 

[aolalde]

Adding capacitors can have negative interactions with system harmonics, therefore a deep power quality study is recommended.

 

[rbulsara]

See thread237-112076

I do not know how large you faciltiy is. It would have been better had you had installed the caps at the motors to begin with in place of adding fixed caps. I assume your fixed caps are at the service entrance or the main board.

Reduction in I2R losses alone seldom justifies buying and installing new PFCs.

 

[hacksaw]

Large plants use them but to correct for losses within the confines of your plant would be hardly justifiable

 

[rbulsara]

Also you do not want to install "more" capacitors then what you already have, if the existing pf is above 0.9 or so. Watch for over correcting. It is another matter if you want to move them to a different location in your facility.

To maintain the sam e pf, if you add new ones at the motors you may have to remove some from the 'fixed' bank.