Novel direct-current traction power supply negative electrode unit frame leakage test and protection device

The utility model relates to a novel leakage test and protection device for a direct-current traction power supply negative electrode unit frame. The circuit comprises a voltage reduction module, a measurement amplifier, a shunt and an analog quantity input module, wherein the voltage reduction module is connected with the frame, the voltage reduction module is connected with the negative electrode and the frame, the voltage reduction module is sequentially connected with the voltage measurement amplifier and the first analog quantity input module, the shunt is connected with the frame, and the shunt is connected with the current measurement amplifier and the second analog quantity input module. After the structure is adopted, a traditional current relay measurement mode is changed, and ashunt + measurement amplifier + analog quantity input continuous measurement mode is adopted; a traditional voltage relay measurement mode is changed, a measurement amplifier and analog quantity inputcontinuous measurement mo