Part I: Application guidelines for high resistance grounding of low voltage common AC Bus and common DC BUS PWM drive systems

High Resistance Ground (HRG) systems have gained popularity in process applications due to their ability to continue operation in lieu of a single line-ground fault and improved ability to limit escalation of the single line-ground fault into a multi-phase event. Guidelines for designing safe and reliable HRG equipment for use on grid systems with linear loads have steadily evolved. However, literature on the characteristics and pitfalls of HRG systems when used with non-linear power converter systems is limited. Part I of the companion paper set is a review of sinewave HRG systems and effect of increased line-ground voltage stress on motor loads during fault conditions. Part II investigates problems of HRG systems used with non-linear power converters such as increased neutral grounding resistor power dissipation, increased motor line-ground transient voltages on faults, susceptibility of ground fault sensing equipment to nuisance tripping, dc bus voltage pump up on faults & nuisance tripping of Main earth leakage breakers. Part II will conclude with a study of HRG zero sequence fault current characteristics and paths observed under various fault locations in a common AC or common DC bus Pulse Width Modulated (PWM) drive system.