Return to Service Failure, Cooperative Troubleshooting

After completing a recloser control replacement at a customer's brownfield substation, the subsequent energized closure of the recloser resulted in an instantaneous recloser trip. No fault or equipment damage was apparent in the field. Electrical testing of the recloser was performed to determine its operational condition and found no problems related to the trip. Recloser control event data and sequence-of-events data was gathered and analyzed to determine the cause of the trip. The data presented by the recloser control did not fit classical fault event signatures which prompted further investigation. Field investigation and desk calculation determined that a significant circulating current event initiated when the recloser closed and caused the trip. This paper details the investigation of this event, highlights the critical characteristics to identify a circulating current event and displays the value of effective communication and coordination between field engineers and design engineers. Event root cause analysis and full lessons learned will be shared.