Bus Conditioner and Discharge Circuit in Floating Ground System Applications

This paper presents a standard DC bus conditioner circuit and highlights safety issues with a floating electric drive configuration in a low leakage and ground current environment. A novel circuit is developed for automatic discharge of the bus conditioner capacitor during the drive shut down. It uses DC bus voltage as an input and a control relay to discharge the capacitor across a resistor. Functional tests were conducted on a 480/690VAC system to assess the performance of the system and circuit reliability. The circuit is validated and results are presented.