Considerations for the Application of an MV High-Speed Grounding Switch for Arc Flash Mitigation of LV Equipment

This paper expands on the work of a previous paper that presented the possibility of a significant reduction of incident energy on the secondary of medium-voltage to low-voltage (MV-LV) transformers with the combination of a high-speed grounding switch (HSGS) and traditional MV current limiting E-rated fuses. It was shown that when the HSGS is applied at a location between the E-rated fuse load terminals and the transformer's primary connection and controlled by relays on the LV side, incident energy can be reduced to less than 1.0 cal/cm
²
. The first paper focused on the results from a high-power test lab, whereas this paper discusses the issues related with its application on typical power systems and lessons learned from installations at several locations. Application considerations include a review of relay requirements, coordination of E-rated fuses, requirements for resistance grounded systems, modeling in analysis software, and field installation considerations.