The secondary power equipment constitutes a system, not just the device itself, such as AC, DC, control circuits, etc. Due to the lack of monitoring methods for some circuits, real-time technical analysis and judgment of equipment status cannot be carried out. Therefore, in terms of the current application status of electrical secondary equipment, strictly speaking, most protections do not meet the conditions for condition based maintenance. The planned maintenance system adopted by power equipment in the power system has serious defects, such as frequent temporary maintenance, insufficient or excessive maintenance, blind maintenance, etc. This causes countries around the world to spend huge amounts of money on equipment maintenance every year.

According to the nature of maintenance work, transformer maintenance is divided into major and minor repairs. Traditionally, oil immersed transformers that require oil suspension (or lifting the bell cover) for maintenance are called major repairs; If there is no need to drain oil, do not lift the core (lift off the bell cover), and only perform external maintenance, oil replenishment, and oil treatment, it is called minor maintenance.

Transformers can be directly thrown into the transformer room using a car crane, or temporary tracks can be set up with wooden tracks. Three steps and lifting chains can be used to lift the transformers onto the temporary tracks, and then the lifting chains can be used to pull them into a suitable position indoors. Transformers should pay attention to their orientation and distance from the wall, which should be consistent with the drawings. The allowable error is ± 25mm. If there are no markings on the drawings, the horizontal distance from the wall should not be less than 800mm, and the distance from the door should not be less than 1000mm. Installation of transformer stand: Install transformer on double pole with a root gap of 2m between the two poles. Buried at a depth of 2m. The distribution transformer stand is fixed to two poles with two or four channel steels, and the height of the stand from the ground is not less than 2.5m. The plane slope of the stand is not more than 1/100. The waist railing should be wrapped with iron wire with a diameter of no less than 4mm for more than two turns, and the winding should be firm. The distance between the waist railing and the live part should not be less than 0.2m. At the same time, dust covers are installed on the high-voltage column heads of the transformer, and warning signs are hung on the transformer.