power factor correction

[curious125]

I understand how and why power factor correction is used, but what I'm not sure of is what effect if any would there be for over correction? (using a larger Capacitor load bank than is required)

 

[gramz]

Using a larger capacitor bank than required will cause the power factor (p.f.) to become leading and is probably more undesireable than a lagging p.f. Utilities usually don't want customers feeding VARS feeding into thier system.

 

[tinfoil]

Actually, sometimes we don't mind it, as it props up our voltage at the end of long feeders, but...

1) Most 'legacy' utility revenue meters cannot distinguish between leading and lagging power factors and will charge you for a poor power factor either way.

2) Some of your facilities equipment may not like the impact of excessive VAR's furnished by capacitors, as they tend to aggrivate the impact of harmonics and cause the voltage to rise above nominal levels.

 

[cbarn24050]

You must never "overcompensate" there is the resonance problem to deal with.

 

[Bung]

Some switchgear (especially older stuff) doesn't particularly like switching capacitive current, either.

A lot of the old utility rules stem from it being easier to control something by having a blanket ban. It is just too hard to deal with thousands of exceptions and how they might upset the system. It's basically a paternal "greatest good of the greatest number" approach. A lot of whiz-bang white-shoe entrepreneurial types hate it 'cos of their blinkered short term "it costs us money" approach to life!

Bung
Life is non-linear...

 

[curious125]

cbarn24050
What is the resonance problem that you spoke of? Would it not be present regardless of leading or lagging p.f.?