Details that are easily overlooked during maintenance of dry-type test transformers:
1. First clean the porcelain bushing and casing, and then check whether the casing, gasket and porcelain casing are cracked, discharge marks or rubber pads are aged, whether the cables and busbars are deformed, and those with cracks should be replaced.
2. Check whether the contact surface of the bus bar is kept clean, the contact surface should be removed the oxide layer and coated with power compound grease.
3. Check whether the grounding of the transformer is good and whether the ground wire is corroded. If the corrosion is serious, it should be replaced.
4. Tighten the lead terminals, pins, grounding screws, and busbar screws. If they are loose, remove the screws, or use a thin flat file to lightly file the contact surface, or replace the spring washers and screws until the contact is good.
5. Clean the dust around the transformer and accessories, and check whether the fire-fighting facilities and ventilation system are in good condition.
6. Use a 2500V shaker to measure the insulation resistance of the high-voltage side, and compare it with the measured value of the transformer before leaving the factory. The insulation resistance should not be lower than 70% of the original data when leaving the factory. If it is unqualified, it should be reported in time.