Here are several common methods for handling multi-point grounding faults in transformer cores: (1) For cores with external grounding leads, a resistor can be connected in series within the core grounding circuit to limit the grounding current. This method should only be used as an emergency measure. (2) For grounding faults caused by metallic foreign objects, the problem can usually be identified by performing a tank removal inspection (uncovering the core). (3) For grounding faults caused by burrs on the core or the accumulation of metal powder, the following methods have proven to be quite effective: Read More

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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