Fire at aging Memphis substation cuts power to 12,000 customers

What happened

On a clear day with no severe weather, an electrical substation operated by Memphis Light, Gas and Water (MLGW) on University Street, north of Hunter Avenue in Midtown Memphis, erupted in flames, sending bright blue sparks and thick smoke into the air. The fault interrupted service and MLGW had to transfer nearly 12,000 customers to other circuits to restore power. Utility officials confirmed at a board meeting the following day that an electrical fault had triggered the fire and that protective equipment, which should have tripped off automatically, failed to operate as designed.

The transformer at the site was damaged, and MLGW said it would need to replace breakers, insulators and cabling. Staff confirmed the substation was built in 1973, making it roughly 50 years old at the time of the incident.

Contributing factors

MLGW officials attributed the failure to the age of the equipment, describing it as vintage, and stated that protective equipment which should have tripped off did not operate as intended. The utility's CEO noted that equipment beyond 30 years in the distribution system becomes more susceptible to failure, and that such failures are typically dramatic when they occur.

Lessons learned

1. Protective relays and breakers at substations must be tested regularly so they trip on fault as designed.
2. Equipment over 30 years old in distribution systems should be inspected and replaced to avoid sudden failure.
3. Substations need circuit transfer options so power can be restored quickly when one site fails.

More lessons on electrical protection and isolation, maintenance, inspection and ageing assets, from every incident on the register.

Not yet known

• Exact cause of the electrical fault
• Cost of repairs and replacements
• Duration of any supply disruption

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Source

fox13memphis.com