NolaTigaBait

When performing a FOP under an unbalanced load, do I just compare the % of drop between each pole based on %?...Obviously the ma's won;t be the same b/c of the current difference...so what do I compare under this scenario?

brian john

At this point some experience and intution come into play. You can apply ohms law and determine the resistance of the contacts or item under test.

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Brian John
Leesburg, VA

jwjrw

You are way too smart to be on here with us common folk.

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The more I learn the less I seem to know......

NolaTigaBait

I must admit that I'm a better mechanic than electrician...I figure it's all in Ohms law...just haveing trouble getting the right direction....At what point would you say that the unbalanced load would make a differnece in the test?...Says if it was 2 or 3 amps unbalanced...would that be a big deal for testing purposes?

micromind

A couple of amps won't make much of a difference.

The percentage idea will work to some degree, but in my experience, even a breaker with the same current on all poles will have a slightly different drop across each pole.

If a breaker pole is bad, it's usually obvious. I know this sounds a bit unnatural for an electrician (we're used to being exact), but you get a feel for these tests, and you guess at what the drop should be, based on the current and the other poles or other breakers. If a pole is bad, the drop will be much higher than you thought it should be.

It's a lot like meggering stuff, it's about 80% experience and about 20% scientific fact.

Rob

Zog

Once you calculate resistance the ANSI spec us all 3 phases are to be within 50% of the lowest reading.

Zog

Nonsense, both are 100% fact. You take measurements and compare the readings to a spec.