The purpose is to inspect the insulation between the relay terminals and the ground. Use a megohmmeter (such as 500V DC). Check wiring & . Protection Relay Testing is the procedure used to verify the performance, accuracy, timing, and operational condition of protective relays installed in electrical systems. These relays monitor electrical parameters such as current, voltage, frequency, impedance, and phase angle. But when it's needed, it has to perform. Servicing protective relays per manufacturer and NETA recommendations ensures they work properly to prevent injury or extensive damage to your plant during. Low Tension (LT) protection relays protect electrical systems by finding abnormal conditions such as Ground faults.