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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?