Microcomputer-based Relay Protection Test Set, abbreviated as "Relay Protection Tester" or "Six-Phase Tester". It is the "all-around examiner" of the secondary circuit (control, protection, and signal systems) in power systems. If previous equipment (insulation resistance, DC resistance, high-current generators) mainly tested the physical health of primary equipment (transformers, cables, switches), then the relay protection tester is specifically used to test the "brain" and "nerves" - that is, whether the logic of relay protection devices and secondary circuits is correct and whether their actions are precise. In 2026, with the widespread adoption of smart grids and digital substations, the relay protection tester has evolved from a simple "signal source" into an intelligent terminal with simulation, automated testing, and GOOSE/SV message analysis capabilities. 1. Core positioning: "Simulator" for secondary systems. Relay protection devices (such as line protection, transformer protection, generator protection) are usually in a "dormant" state, only tripping when grid faults (short circuits, grounding, overloads) occur. Pain point: We cannot actually create a grid short-circuit accident to test the protection device. Solution: The relay protection tester can accurately simulate various fault scenarios (such as A-phase grounding, BC phase-to-phase short circuit, three-phase oscillation, etc.), output corresponding voltage (U) and current (I) signals to the protection device, and observe whether it trips correctly within the specified time. 2. Core functional modules (2026 version) A. Multi-phase output capability (mainstream is 6 phases) Configuration: Typically provides 6 voltage (