First of all, maintenance of power equipment is an urgent need of the equipment itself. The equipment is exposed to the air for a long time, the moisture and dust will reduce the efficiency of the equipment, the parts are easy to loose in the alternating between hot and cold, and the aging of the equipment will affect the safety of the system operation. Second, electricity regulations clearly require regular maintenance of equipment. Related requirements of power supply Regulations Q/CSG 1 0007-2004 Regulation for Preventive Test of Electric Power Equipment provides relevant requirements for preventive test of various electric power equipment, which is used to judge whether equipment meets operating conditions, prevent equipment damage and ensure safe operation.