Protection relays are tested by sending simulated electrical signals that mimic real fault conditions. Engineering use: Relays are used on feeders, transformers, buses, motors, generators, and transmission lines to protect equipment and improve system reliability. What controls it: Relay performance depends on the protected zone, CT/PT inputs, pickup settings, time delay, breaker clearing time, trip. To conduct the tests effectively the following devices and equipment are required: Primary Injection Test Kit – for injecting large currents directly into CT circuits. Clamp Meter – used for. Relay protection testing verifies the functionality and reliability of protective relays in electrical power systems.