The design of collector systems with a single-grounding reference located at the substation is a generally accepted practice in utility-scale solar facilities. The rationale behind this practice is that the inverters behave as current sources and therefore, during switching transients, these source-types do not enforce line-to-line voltage relationships at their output terminals. The objective of this paper is to uncover conditions where the overvoltages impinged on the collector system arresters and across the contacts of the feeder circuit breakers exceed their withstand capabilities. Examples are presented to show how the use of grounding transformers and circuit breakers with interlocked grounding switches eliminate circuit breaker restrikes, reduce overvoltages and maintain the effectively grounded conditions of the collector system.
