Part II: Application guidelines for high resistance grounding of low voltage Common AC bus & Common DC bus PWM drive systems

High Resistance Ground (HRG) systems have gained popularity in process applications due to their ability to continue operation after a single line-to-ground fault and ability to limit escalation of a single line-to-ground fault into a multi-phase event. Part I of the companion paper set guidelines for designing safe and reliable HRG systems on industrial power systems used with linear loads and the effect of increased line-ground voltage stress on motor loads during fault conditions. However, literature on characteristics and pitfalls of HRG systems when used with non-linear power converter systems is limited. Part II investigates anomalies of HRG systems used with non-linear power converters such as neutral voltage shifting, increased line-ground transient fault voltages for both motor and AC source terminals and their voltage compatibility issues, increased neutral grounding resistor power dissipation, susceptibility of ground fault sensing equipment to nuisance tripping, and dc bus voltage pump up on faults. Part II also investigates HRG zero sequence fault current characteristics and paths observed under various fault locations in Common AC or Common DC bus Pulse Width Modulated (PWM) Adjustable Speed Drive (ASD) system. Part II concludes with a summary of application guidelines when using ASD HRG systems.