A DC primary current injection test system is used to test and verify the performance of protective relays, circuit breakers, and other electrical equipment. It is designed to inject a high current into the primary side of the electrical system to simulate fault conditions and determine the response of the protective devices.

This type of test system typically includes a high current DC power source, control and monitoring equipment, and safety features to ensure the proper and safe operation of the test. The injected current allows for the testing of the entire protection system, including the trip time of protective relays and the performance of circuit breakers under fault conditions.

These tests are crucial for ensuring the reliability and safety of electrical systems, especially in critical infrastructure such as power plants, substations, and industrial facilities.