The  Cause:

Today's  automated facility relies heavily on electronic systems, which dramatically  increase harmonic noise on the line side of the power distribution plant.  While the fundamental current levels may be within specification, the  harmonics can add the same amount of current as the fundamental. Unmitigated,  these harmonics are demons of heat, trips, lockups and poor power factor.  Passive solutions will correct one problem but add another. If the load  condition varies, passive systems can actually cause resonances that  can accelerate failure.