Harmonics – Ideally all loads and sources have a pure sinusoidal current waveform. But unfortunately, the true waveform of most equipment is very different. Nonlinear loads like for example the diode input bridge of a 6 pulse drive, are causing a distortion of the mains voltage.
This distortion evaluated by the Total Harmonic Distortion THD, typically evaluates frequencies from the 2nd up to the 40th or 50th harmonic. In a 50Hz Network this is the area between 100Hz and 2.5kHz.
The impact of the harmonic distortion is diverse, and the most typical effects are:
o Transformer overload
o Capacitor bank (PFC) overload
o Increased energy costs
o Decreased equipment lifetime
o Prone to failure equipment
o Vibration damage on rotating equipment