1. Periodic test contents of high-voltage test transformer include:

① Oil sample testing-performance indicators such as withstand voltage and impurities are carried out every three years, which can shorten the period of long-term full load or overload operation of the transformer.

② The high and low voltage insulation resistance should not be less than 70% (10MΩ) of the original factory value. The DC resistance of the winding at the same temperature, the difference between the three-phase average value should not be more than 2%, and it should not be compared with the result of the last measurement. Should be greater than 2%.

③ The grounding resistance value of the high-voltage test transformer is measured every two years.

④ The cycle of cleaning and inspection after power failure is determined according to the surrounding environment and load conditions, usually once half a year to once a year; the main content includes eliminating the defects found in the inspection, cleaning the porcelain sleeve, replacing the cracked or aging rubber pad, and checking and tightening the connection point. Lack of oil and oil replenishment, check and replace the silica gel of the respirator, etc.

2. The daily maintenance methods of high-voltage test transformers include:

① Grounding of the transformer

② The transformer shell should be grounded reliably, and the working neutral wire shall be laid separately from the neutral ground wire, and the working neutral wire shall not be buried in the ground.

③ The neutral grounding loop of the high-voltage test transformer should adopt detachable connecting bolts near the transformer.

④ The grounding of a transformer equipped with a lightning arrester should meet the requirements of the trinity; that is, the neutral point of the transformer, the transformer housing, and the grounding of the arrester should be grounded in one place and grounded together.