Electrical Energy is converted to Mechanical power by using magnetic core and alternating current passing through magnet wire wound around the core.
When no Current passes through the Magnet wire the internal granules(Dipole) of magnetic core are stationary. CRGO ( Cold Rolled Grain Oriented) .
When AC current passes through the magnet wire the internal grains(Dipole) in the magnetic core rotate as per the alternating current.
There are losses generated like core loss, hysteresis loss, Eddy Current loss in magnetic core and dissipated in the form of heat. The magnetic core is designed for 50Hz the movement of grains is same as 50Hz voltage waveform.
If any distortion arise in mains voltage waveform, magnetic core respond to distortion by producing extra heat as the grains movement does not change abruptly but tend to move at primary frequency 50Hz. Any distortion in the voltage is converted to heat in core .
For distortion or high frequency on voltage waveform, capacitors provides low impedance path and reduce the distortion maintain the voltage waveform and reduced core losses achieved.