It is a value used to determine how much harmonic current a transformer can handle without exceeding it's maximum temperature rise level. K-factor values range from 1 to 50. K-factor of 1 is used for linear loads only, and a K-factor of 50 is used for the harshest harmonic. hase, two phase or three phase we need to do detailed modeling. However, many times in the field distribution ate method we are assuming that loads are balanced and lines are transposed. This article explains the concept of the K-factor, the origin and effects of harmonics, how K-ratings are defined, and practical guidelines for selecting appropriate transformers. Eaton's K-Factor transformers address the problems caused by non-linear loads and harmonics. Harmonics on a vibrating string are analogous to harmonics in a.