These ground-fault relay test units are used on substations, motor control centers, central distribution panels, switchboards, and test benches to verify relay operations. Our relay test and management software (RTMS) has a solution available for any job requirements, exceeding your expectations. With Megger as your trusted partner, you can overcome the most complex of relay protection test challenges. Test blocks enable test technicians to quickly and safely isolate protection relays so that test signals may be injected and system. The DDG Primary Current Injector Test Set is a high-current test device used to generate controlled large currents for safety testing, CT calibration, temperature-rise and. COMBITEST also means additional personnel safety during testing.