The relay protection tester uses a generation of high-speed DSP digital signal processor as the core, adopts full-fidelity and high-performance amplifiers, has high output accuracy and good waveforms, and has stable performance. It can facilitate various tests on equipment and devices. Relay calibration procedures, powerful functional testing software can provide a variety of verification and search methods of complete sets of microcomputer protection and automatic device automatic test procedures: line protection, differential protection, impedance protection, synchronization, etc., various fault program simulations, It can truly simulate and replay the actual various faults, system oscillations and reclosing actions on the scene.