The core should be flat with intact insulation varnish film and tightly stacked laminations. The silicon steel sheets on the edges should not be curled up or wavy. The surface of all core parts should be free of oil sludge and impurities. There should be no short circuits or (lapping) between laminations, and the joint gaps must meet the required specifications. Read More

Temporary troubleshooting methods for transformer cores when shutdown is not possible: If there is an externally routed grounding wire and the fault current is relatively high, the grounding wire can be temporarily disconnected for operation. However, enhanced monitoring is required to prevent a floating potential from appearing on the core if the fault point happens to disappear. Read More

Loose yoke clamps or other metal components can cause vibration, leading to core overheating, discoloration, and scorched varnish film. Upon inspection, if the fault is severe, remove the faulty laminations for repair, leaving the intact parts untouched. When reassembling the damaged laminations, the repaired laminations should be interleaved and mixed with the intact ones. After the repair, core loss and temperature rise tests must be conducted. Read More