1. Check for abnormal sounds and vibrations.
2. Check for discoloration caused by localized overheating, corrosion from harmful gases, or other factors leading to electrical creep and carbonization on the insulation surface.
3. Verify the normal operation of the transformer's air-cooling system.
4. High- and low-voltage connections should not overheat. Cable heads should be free of leakage and creepage.
5. The temperature rise of the windings should be monitored according to the insulation material grade used in the transformer; the temperature rise must not exceed the specified value.
6. Support insulators should be free of cracks and discharge marks.
7. Check for loose winding clamps.
8. Indoor ventilation and core air ducts should be free of dust and debris blockages; the core should be free of rust and corrosion.
