Transformer Maintenance

1. Isolate the low-voltage side circuit breaker of the transformer undergoing maintenance, remove the operation fuse for the control power, and hang a "Do Not Close" sign at the switch handle.

2. Disconnect the circuit breaker on the high-voltage side of the transformer, close the grounding switch, fully discharge the transformer, lock the high-voltage cabinet, and hang a "Do Not Close" sign at the switch handle.

3. Maintenance of transformer boxes involves first cleaning the porcelain tube and housing. Next, inspect the housing, gaskets, and porcelain tubes for cracks, discharge marks, or signs of aged rubber pads. Check for any deformation in cables and busbars. Replace any items found to be cracked.

Ensure the busbar contact surfaces remain clean, removing any oxidation and applying electrical composite grease.

Ensure the transformer's grounding is sound, and inspect for corrosion on the grounding wire; replace if severe corrosion is detected.

6. Secure wire terminals, pins, grounding screws, and busbar screws. If loose, unscrew and remove, or gently file the contact surface with a fine flat file, or replace the spring washers and screws until a good contact is achieved.

7. Clean dust from around the transformer and its accessories, and check that the fire safety equipment and ventilation system are in good working order.

8. Disconnect the grounding switch on the high-voltage side and securely lock the high-voltage switch assembly. Use a 2500V megger to measure the insulation resistance. Compare it with the pre-manufacturing measurement of the transformer, and the insulation resistance should not be less than 70% of the original data at the time of manufacture. If it does not meet the standard, report and handle it promptly.

9. Re-close the grounding switch on the high-voltage side to allow the transformer to discharge.

10. Inspect the transformer room and transformers for any leftover tools, and evacuate the site.

11. After disconnecting the control power of the low-voltage side circuit breaker, rehang the "Do Not Close" sign to prevent back-feeding electricity to the transformer.

12. Disengage the high-voltage side grounding switch, re-inspect the transformer site and the control lines on the low-voltage side. Upon confirmation of no issues, close the high-voltage side circuit breaker of the transformer and allow it to undergo trial operation, then remove the high-voltage side identification sign.

Ensure detailed maintenance trial run records.