The periodic tests of high-voltage test transformers include:
① Oil sample detection - withstand voltage, impurities and other performance indicators shall be conducted once 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 shall not be less than 70% (10M Ω) of the original factory value. The difference between the three-phase average value of the DC resistance of the winding at the same temperature shall not be greater than 2%, and shall not be compared with the last measurement result. It should be greater than 2%.
③ The grounding resistance value of high-voltage test transformer shall be measured every two years.
④ The cycle of cleaning and inspection after power failure is determined according to the surrounding environment and load conditions, generally once every six months to once a year; The main contents include eliminating the defects found in the inspection, cleaning the porcelain bushing, replacing the cracked or aged rubber gasket, checking and tightening the connection points, oil shortage and supplement, checking and replacing the silica gel of the respirator, etc.
The routine maintenance methods of high-voltage test transformer include: ① the grounding of transformer ② the transformer shell should be reliably grounded, the working zero line and the zero line grounding wire should be laid separately, and the working zero line should not be buried. ③ The neutral grounding circuit of the high-voltage test transformer shall adopt removable connecting bolts near the transformer. ④ The grounding of transformer equipped with lightning arrester shall meet the requirements of trinity; Namely, the neutral point of the transformer, the shell of the transformer and the lightning arrester shall be grounded together at one place.