Sym interrupting vs. Adj Sym interrupting 1

[kookypedia]

Guys,
ETAP SC report has Symm KA rms and Adj. Sym KA rms and it uses M.F which,

Adj. Sym KA rms = M.F. x (Sym KA rms)

I am wondering how ETAP calculates M.F. ?

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[davidbeach]

Out of the relevant IEEE breaker rating standards?

 

[kookypedia]

I don't change any setting in the breakers and it is strange that some breakers have M.F>1 (like CB6 and CB7) and some have M.F.=1 (like CB11 and CB9)

An investment in knowledge pays the best interest (Benjamin Franklin).

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[davidbeach]

It has to do with the types of breakers, the ratings of the breakers, and the actual system power conditions. Note that the two that are getting adjusted were tested at a more favorable power factor than the rest; they're seeing an X/R that's too high while that same X/R is fine for the breakers with the lower test PF. Try the IEEE Blue Book; the Red Book may also have some information.

 

[cuky2000]

See if the graphic and formulas below could help

 

[kookypedia]

cuky2000,
Thanks a lot for your awesome comment.

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