Three-phase common mode chokes are used on frequency inverters to reduce high frequency stray fields’ associated PWM controller technology. These stray fields appear as common mode voltages and currents that can flow through parasitic capacitance onto the ground system, as well as causing motor bearing currents.

Common mode chokes can reduce such stray fields and the dangers posed by them. Common mode chokes are equipped with one or two additional return flow core legs magnetic field scan circulate to remain trapped in the reactor itself.