Passive unbalance compensation device for three-phase variable loads

This paper describes constitution and design characteristics of a passive unbalance compensator for variable loads in three-phase four-wire industrial installations. Unbalance compensator is integrated by three-phase connections of variable coils and capacitors. Inductance and capacitance values of those elements and unbalance power supplied by the compensator can be changed by switches commanded by an electronic control circuit. The minimum unbalance power supplied by the compensator is the “power of the unbalance step”. This quantity defines composition and values of the elements of the “unbalance step”, which is the basic three-phase connection of coils and capacitors in the compensator. Since unbalances in power systems are caused by active and reactive loads, two unbalance steps have been defined: active and reactive. Finally, unbalance compensator operation has been tested for an industrial installation.