Abstract: An electrically variable current limiting reactor which is usable in association with a power supply for an electrostatic precipitator is disclosed herein. The current limiting reactor is capable of having the inductance value thereof varied responsive to system operation conditions. Most particularly the inductance of the current limiting reactor can be modified responsive to the form factor of the sinusoidal AC input current to the power supply transformer. Additionally the inductance of the current limiting reactor can be controlled responsive to the fractional conduction of the full wave rectified current waveform at the output of the full wave rectifier of the power supply. Other conditions can be monitored to control the inductance value of the current limiting reactor such as physical system parameters. An automatic operating control may modify the inductance of the current limiting reactor responsive to the current entering the primary of the transformer of the power supply.