Power Transfer Switch Maintenance and Testing

The reliability of the transfer switch in an Emergency Power Supply System (EPSS) determines the reliability of the entire system. During an outage, the component is responsible for changing the electrical load of a building from the primary source (i.e. utility feed) to the secondary source (i.e. generator feed). To ensure the component works as expected, building owners should have it maintained and tested as outlined below:

Weekly Inspection

During the weekly inspection of the EPSS, the component should be checked for signs of oxidization, dirt accumulation, and overheating. If these signs are not present, and the component is in the correct operating position, it should pass inspection.

Monthly Testing

The National Fire Protection Association (NFPA) requires Level 1 and Level 2 generators to undergo a monthly test. As would occur during an outage, the switch signals the EPSS to start, monitors it during startup, and changes over the building’s load after startup is complete. If the EPSS fails to start, kicks off soon after starting, or fails to carry the load, a recalcitrant power transfer switch might be the problem.

Prime Power performs monthly EPSS testing as part of its generator services in Carolina.

Annual Maintenance

The NFPA requires annual maintenance to be performed on the components to prevent overheated connections, worn contacts, loose cable terminations, and other internal problems. Before investigating the component, the technician disconnects it from the primary source and secondary source, cleans the cabinet that houses it, and then cleans the component.

Next, the component is inspected for signs of deterioration. After their covers are removed, the contacts are inspected. After the covers are replaced, the wires that connect to the device are inspected for cracking, and the control connections are inspected for deterioration. The connections are then re-torqued.

Annual Testing

During the monthly test, manipulating circuits in the component simulates an outage, but simulating a real outage is recommended for the annual test. “Opening up” a building’s EPSS and testing it under real conditions puts the ability of the component to start the EPSS and access its feed to the ultimate test.

Infrared testing should also be performed on an annual basis. By scanning EPSS equipment with an infrared scanner, technicians can uncover “hot spots” in components that indicate early problems. Often, these problems can be fixed before they create larger problems. Infrared testing is fast and affordable. An entire facility can often be scanned in a day.

Prime Power can help

A power transfer switch is an integral part of an EPSS. If it malfunctions, a building cannot access secondary power during an outage. Prime Power can ensure that the transfer switch in your EPSS is ready to perform by inspecting, maintaining, and testing it according to the processes above.

The processes above are a basic overview of how transfer switches should be maintained and tested on a weekly, monthly, and annual basis. For specific questions about EPSS maintenance and infrared testing, call Prime Power, the premier provider of generator services in Carolina, today.

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