For the 2-winding transformer, induction motor and generator, the factor is:
(1.0 + 0.1*Norder^1.5), where Norder is the order of the harmonics.
HVDC-AC Harmonic Interaction Part II -AC System Harmonic Model with Comparison of Calculated and Measured Data
Breuer, G.D.; Chow, J.H.; Gentile, T.J.; Lindh, C.B.; Addis, G.; Lasseter, R.H.; Vithayathil, J.J.;
Power Apparatus and Systems, IEEE Transactions