Backup generator operations

Ensuring emergency systems are tested and operational is critical to limiting a disruption from widespread and localized power outages. After a recent loss involving an automatic transfer switch (ATS) for an emergency generator, a manufacturing operation discovered the importance of incorporating the ATS in their emergency testing procedures. Learn more about this loss below and how it could have been prevented.

A manufacturing operation received an alert that its building’s servers were offline during a widespread power outage. Upon inspection, the warehouse was without power, and the 500-kilowatt emergency generator was not operational as the ATS was getting stuck between the utility and generator set. A temporary ATS was delivered to the premises to restore power, and the policyholder’s repair vendor suggested the ATS sustained an electrical arcing event due to the recent outage.

FM Boiler Re was notified of the loss seven weeks later and engaged an electrical engineering consultant to assist in determining the cause and extent of damage. During an interview with the policyholder, FM Boiler Re determined that the location had not experienced a recent power loss, contrary to the repair vendor's original suggestion. The electrical engineer advised that the electronic controls for the ATS were older – approximately 17 years old – and confirmed that when the ATS was required to switch back over from generator set provided electrical power to utility electrical supply, the ATS failed. The exact cause or date of failure was never determined, though the entire ATS was replaced.

As part of their inspection, the electrical engineer worked with the policyholder’s in-house maintenance staff to simulate an off-hours outage. No additional damage was found; however, it was discovered that the monthly emergency generator set testing procedures did not include testing or verification of an operational ATS.

The policyholder was advised that the ATS should be integrated into an annual electrical preventive maintenance schedule, which includes:

• Visual inspection for corrosion and cleaning Lubrication of mechanical parts
• Checking the torque/tightness of bolted cable connections
• Contact resistance testing of all three phases Insulation resistance testing of conductors for phase-to-phase and phase-to ground faults
• Throwover test to ensure the ATS functions properly

Overall, periodic testing may have assisted the policyholder in identifying the potential issue and limiting the disruption of renting a temporary ATS and power cable for two months. Following the guidelines from their respective manufacturers, testing of the emergency generator along with its ATS will verify their reliability when they are needed most – in an emergency. Additionally, more expedited notice of the loss by the policyholder would have allowed FM Boiler Re to mitigate loss expenses.