Electrical Substation Transformer Protection

Begin by switching off the circuit breaker of the substation transformer, then engage the grounding switch. Once the transformer is completely discharged, secure the high-voltage cabinet with a lock and affix a “Do Not Operate” warning label to the switch to prevent accidental activation.

For box-type transformer maintenance, thoroughly clean the porcelain bushings on the outer casing. Conduct a detailed inspection of the transformer’s shell and gaskets: check for cracks, splits, or signs of damage, and examine rubber gaskets for deterioration or aging. Replace any defective or worn components immediately to maintain operational integrity.

Inspect the substation transformer’s grounding system comprehensively to ensure it functions properly. Check the grounding conductor for damage, corrosion, or wear—replace it promptly if severe defects are identified.

Verify the security of lead terminals, grounding screws, and busbar fasteners. If any screws are loose, tighten them firmly. For poor electrical contact, use a fine flat file to smooth the contact surfaces (removing oxidation or debris) or install spring washers alongside the screws to enhance connection stability and ensure optimal conductivity.

Disengage the high-voltage side grounding switch, lock the high-voltage cabinet, and use an insulation resistance tester (megohmmeter) to measure the transformer’s insulation resistance per standard procedures.

After completing the test, re-engage the high-voltage side grounding switch to discharge the box-type transformer thoroughly, eliminating any residual electrical charge. Conduct a final sweep of the substation transformer room and the transformer itself to remove any foreign debris, tools, or leftover materials. Ensure the work area is fully cleared before concluding the maintenance process.