Cutler Hammer p.f. correction system

[sceepe]

I have a client who is going to install a power factor correction system on his service and I was wondering if anyone has experience with the Eaton (Cutler Hammer) AutoVar system.

My biggest concern is that it is an auto switching system that switches capacitors on line as the power factor drops. However, the system only monitors one phase. See this link. If the capacitors are added to all phases based off the p.f. measured on one phase, aren't you setting up a potential overcorrection situation if the load is unbalanced?

http://www.eatonelectrical.com/unsecure/cms1/TD02607003E.PDF

 

[beanland]

Re: Cutler Hammer p.f. correction system

Looks like no one else knows...

Yes, you could "overcorrect" lightly loaded phases. However, most utilities only require correction to about 95% power factor. At 95% PF reactive power (VArs) is 33% of true power (kW). If the client corrects to 95% there will still be significant reactive load so there will have to be serious unbalance to cause leading power factor on another phase. Need to fix the unbalance, anyway.

Even if your overcorrect, the utility will accept the leading VArs. If the electric meter is a typical 3-element type, the utility only looks at the total 3-phase loading anyway.