Re: Stability Factor: K-Factor

Spir Georges GHALI

Dear Mr. Steven ;


first, thanks for your reply, and be sure for me there’s no any confusion.


Please let me clarify the following :

– The percentages of Harmonics are certainly ” THD-I “ ( Total Harmonics Distortion of Current ) and not ” THD-V

– The mentioned formula between ” K-Factor ” and ” the Transformer’s Power ” is ” K-Factor = S ( kVA ) * IL ” as IL is the load harmonic, please let me clarify the following points :

  • This formula is ” linear “, but the relation between K-Factor and the Transformer’s Power is not a linear.
  • As I mentioned, there’s a Curve ( not linear ) between ” the Percentage of Non-linear Loads compared with the total installed loads ” and the ” Derating Factor “, when we obtain this factor, we use the following formula : S(new) = S / Derating Factor. Noting that I use this curve during designing step of any site if the derating of transformer is necessary, and if you want, send me your e-mail to send it you.

– About the type of used motors : from my experience, most of LV motors even till 300kW are Squirrel Cage Motors. noting that all Motors are Induction Motors. Please clarify if there’s another kind, and what?