Power-Quality Investigation of Surge Protective Device Failures During Open Transition for a Wastewater Treatment Facility

To date, many papers have been written about various concepts in power system grounding, explaining the application, advantages, and disadvantages of each of the solidly grounded, resistance-grounded, and ungrounded systems. The purpose of this paper is not to explain the theory behind the aforementioned concepts but rather substantiate them with actual field measurements during a failure of a surge protective device. The measurements taken, utilizing digital power-quality monitors, and subsequent analysis will demonstrate the adverse effect of arcing ground faults on ungrounded systems as system voltages escalate to undesirable values. This paper will then examine high-resistance grounding as a superior solution from a service-continuity perspective with a beneficial dampening effect on high-voltage transients that exist on ungrounded systems during arcing ground faults. Consequently, this paper will discuss the operational precautions that the end user must be aware of before proceeding with the implementation of a high-resistance-grounding scheme.