Why use K-Rated Transformers
In recent years, there has been a concern on harmonic currents generated by non-linear loads on electrical power systems. Non-linear devices are everywhere. To name a few, they can be an induction heating equipment, telecommunication equipment, solid state motor drives, computers, etc. These harmonic currents cause excessive heating and premature failure in transformers.
Non-Linear Load and Harmonic effects on Transformers
The presence of harmonic content causes the increase in losses and heating.
Typically, there are 2 types of losses:
This includes copper loss (I2R) and winding eddy current loss
No-load loss is proportional to voltage and frequency. The presence of harmonic content increases the frequency. With higher flux density, there will be higher hysterisis losses.
Choosing a K-Factor Rating
The effect of harmonic content can be defined mathematically by the term “K-Factor”. To determine whether the K-Factor transformer is sufficient to compensate the harmonic, measure the value using a power analyzer and compare to the K-Factor of the transformer. The K-Factor rating of transformer should be higher than the measured value.