This standard specifies the items, cycles, and requirements for preventive testing of various power equipment to determine whether the equipment meets operating conditions, prevent equipment damage, and ensure safe operation. This standard is applicable to AC power equipment of 500kV and below. This standard does not apply to high-voltage direct current transmission equipment, mining and other special conditions of power equipment, nor does it apply to electrical equipment and safety equipment such as relay protection devices, automatic devices, measurement devices, etc. in power systems. Equipment imported from abroad should be based on the product standards of the equipment and executed in accordance with this standard. The provisions contained in the following standards are incorporated into this standard by reference. At the time of publication of this standard, all versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB 261-83 Determination of Flash Point of Petroleum Products GB 264-83 Determination of Acid Value of Petroleum Products GB 311-83 Insulation Coordination High Voltage Test Technology for High Voltage Transmission and Transformation Equipment