Pre-test: The full name is preventive test. Generally speaking, the primary equipment of the power system is to find hidden dangers of the equipment during operation, prevent accidents or damage the equipment. Inspection, test or monitoring of the equipment also includes taking oil samples or Tests performed on gas samples. Preventive test is an important link in the operation and maintenance of power equipment, and it is one of the effective means to ensure the safe operation of power equipment. For many years, the high-voltage power equipment of electric power departments and large industrial and mining enterprises have basically been tested in accordance with the requirements of the "Preventive Test Regulations for Power Equipment" Defects play an important role. Regular inspection: The full name is regular inspection, which is similar to the pre-test. Generally speaking, it is the secondary equipment of the power system. I have n’t heard of the item inspection, but I ’ve heard of the item placement, which means that the items are ordered in order to facilitate the production work.