Maintenance of dry-type transformers

1. Check whether the winding surface is cleaned. The sheath of the winding cable should be detailed and not damaged, and the grounding resistance should meet the regulations. If there is damage to the exposed transmission line on the surface of the winding turn, bundling should be carried out.

2. Check whether the winding is deformed or offset. The windings of each phase should be ordered neatly and the gaps should be well-proportioned. All windings should be free from skew and offset, and there should be no obvious pop-up in the radial direction of the transmission line. If there is any deformation, it should be repaired immediately.

3. Check whether the oil passage is blocked by insulating layer, oil or dirt (such as silicone rubber powder). If necessary, scrub gently with a soft brush (or with satin, plastic foam). The main oil passage should be kept unobstructed, free of oil and other dirt accumulation.

4. Lightly press the winding surface with your fingers to check the insulation layer.

5. Check the two-color baffle and enclosure for damage, discoloration, deformation, and charge and discharge marks. In case of abnormality, other two-phase enclosures should be opened for inspection and maintenance.

6. The pressure nail of the winding should be tightened, and the check nut should be tightened.

7. Check whether the protective layer pads around the winding are offset and fall off.