Harmonic Mitigating Transformers, or HMTs, are specifically designed to minimize the voltage distortion and power losses that result from the harmonics generated by non-linear loads such as personal computers. K-rated transformers, on
the other hand, are simply designed to prevent their overheating when subjected to heavy non-linear loading, but do very little to reduce the harmonic losses themselves. And as for voltage distortion, they perform virtually no better
than conventional delta-wye transformers.