Protected compensating switchboards with the power of 100 kvar up to 1000 kvar are suitable, where the degree of network affection by non-linear appliances (frequency converters, controlled and uncontrolled rectifiers, UPS, induction heaters …) is high and where its material increase is assumed in the nearest future. Protective chokes are installed upstream capacitors of individual compensation steps (stages); these protective chokes create the resonance circuit with the capacitors tuned below the frequency of the lowest harmonic present in the network, thus preventing harmful resonance.
An example of solution of the indoor compensation is presented, a similar compensation can also be realized in the outdoor version.