Circuit breaker explosion and oil fire disable Powell substation

On 29 June 2019 the Vining Substation on North Ingalls Street in Powell, Wyoming lost power at around 5am. On-call city electricians attended and, following standard procedure, switched a circuit breaker back on from a separate control building. The breaker exploded, damaging nearby oil-filled regulators used for cooling. The oil ignited, sending flames from the equipment. Workers called emergency services immediately. No one was hurt, and the city administrator noted that staff were kept at a safe distance because the breaker is operated from a building on the property rather than in front of the energised equipment. The fault caused prolonged power outages across the city. Technicians examining power flow data found a fault across all three phases but could not pinpoint a cause. The substation equipment was reported to be about 30 years old and at the end of its design life. Power was restored using temporary, cobbled together repairs while parts for lasting repairs, with lead times of up to 46 weeks, were sourced. Initial repairs were expected to cost the city about 150,000 US dollars, and the council approved emergency procurement and a contract for a mobile substation if needed.

Ageing substation equipment reported to be around 30 years old and at the end of its design life. The root cause of the initial outage and of the breaker failure could not be determined, although data showed a fault across all three phases.

1. Switching operations carried out from a separate control building can keep personnel clear of equipment that may fail violently when re-energised.
2. Substation equipment approaching or past its design life warrants prioritised replacement or enhanced condition monitoring.
3. Long lead times on high voltage components, up to 46 weeks in this case, make spares strategies, mutual aid arrangements and mobile substation contracts important to restoring firm supply.
4. Emergency procurement provisions allow rapid unbudgeted repairs when normal tendering would delay restoration.
5. Single-substation supply leaves a whole town exposed, so network redundancy should be assessed.

News report via Google News