K-Factor Ratings of K-4, K-13 and K-20. Three Phase. 15-500 kVA for K-4, 15-300 kVA for K-13 and K-20. K-Factor transformers are designed to reduce the heating effects of harmonic currents created by loads like those shown in the chart below. The K-Factor rating is an index of the transformer's ability to withstand harmonic content while operating within the temperature limits of its insulating system. K-Factor transformers have UL ratings of K-4, K-13 and K-20.
These specialized transformers feature conductors capable of carrying the harmonic currents of non-linear loads without exceeding the temperature rating of the insulation system. The basic design takes into account the increase in naturally occurring “stray” losses caused by non-linear loads that can cause standard transformers to dramatically overheat and fail prematurely. The core and coil design manages the DC flux caused by triplen harmonics that can cause core saturation, voltage instability and overheating in a standard transformer.
