Excitation meets resonance

Resonance effects can be observed in industrial medium and high voltage grids quite often at low frequencies. The parallel resonance in such cases is usually between the sum of the cable capacitances and the transformer inductivity. If large drive applications are connected to resonant grids, very high voltage distortions will occur.

In the case showed in the picture on the right, the excitation is caused by 12-pulse rectifiers of large drives. Faults happened first in the low voltage grids, which are fed by the medium voltage.

Solutions are usually passive filters. Visit our website for news on this case.