High、medium voltage reactive power automatic compensation device automatically tracks and switches reactive power according to the power grid and load conditions of 6kV and 10kV power supply buses through the capacitor bank of the control system, with the power factor reaching above 0.9. Greatly optimize the power quality, save losses and reduce consumption, and improve the transmission capacity of the power transmission and distribution system. Arc suppression and overvoltage protection device is a product developed to quickly eliminate the harm to electrical equipment caused by arc grounding of neutral point indirect grounding system. The device mainly consists of a three-phase combined overvoltage protector DCB, a high-voltage vacuum contactor JZ which can be controlled by phase separation, a microcomputer controller, a high-voltage current-limiting fuse assembly FU, a voltage transformer PT with an auxiliary secondary winding and the like.