Arc suppression cabinet is essentially a voltage transformer cabinet with arc suppression, harmonic suppression and overvoltage protection functions. When the neutral point ungrounded operation mode is adopted in China's power grid, if a single-phase metallic grounding fault occurs, it is allowed to operate for 2 hours because it will not endanger the insulation of normal electrical equipment, but if intermittent single-phase arc grounding occurs, it will generate a very high arc overvoltage. The amplitude of the non-fault phase overvoltage can be as high as 3.5 times of the normal phase voltage. It will seriously threaten the insulation of electrical equipment and even cause insulation breakdown. In fact, the arc-suppression cabinet is not to use the traditional arc-suppression coil to compensate the current when the arc grounding occurs in the power system, but to use the high-voltage contactor in the cabinet to directly and reliably ground the arc grounding phase of the bus, so as to achieve the purpose of arc-suppression, which will not generate arc overvoltage and protect the line and equipment.