How to troubleshoot excessive temperature rise in a current transformer?

I. External Connection and Contact Status Inspection

1. Primary Connector Tightness and Contact Condition: Check if the P1/P2 terminal connection bolts are loose and if the spring washers are flattened; observe the connectors for discoloration or burning marks to determine if excessive contact resistance is causing localized overheating.

2. Secondary Circuit Integrity: Confirm that there are no open circuits in the secondary side S1/S2 circuit, and that the terminal block wiring is secure to prevent overheating caused by core saturation and a surge in eddy currents due to open circuits.

3. Grounding System Verification: Check if the casing and secondary side have a reliable single-point grounding to avoid multiple grounding points forming circulating currents or ungrounded circuits causing floating potential and abnormalities.

II. Internal Fault and Body Status Detection

1. Infrared Thermal Imaging to Locate Hot Spots: Use an infrared thermal imager to detect if the body temperature exceeds 80℃ or the connector temperature exceeds 130℃; immediately shut down the transformer; use the thermal image to determine whether the temperature rise is overall or localized overheating, and to differentiate between internal faults and poor external contact.

2. Insulation Resistance Measurement: Use a 2500V megohmmeter to test the insulation resistance between the primary winding and the secondary winding to ground. A resistance value below 1000MΩ may indicate internal moisture, insulation deterioration, or inter-turn short circuit.

3. Sound and Odor Judgment: If a crackling discharge sound, burning smell, or smoke is heard during operation, it indicates internal insulation breakdown or winding burnout, requiring immediate power outage.

III. Design and Selection Matching Verification

1. Rated Current Compliance: Verify that the rated primary current of the transformer covers the maximum load on site (e.g., over 2000A for 110kV lines) to avoid excessive temperature rise under high current due to insufficient design current.

2. Secondary Winding Parameter Rationality: Check if the secondary wire diameter is too thin or the number of turns is excessive. These design defects increase internal resistance and heat generation, especially under high current.

3. Product Technology Comparison: Traditional instrument transformers can experience temperature rises of 70-80℃ under a 3000A high current, while new products (such as the Yicitong solution) can control the temperature rise to ≤35K through grouped winding and redundant wire diameter designs, significantly reducing risk.

IV. Heat Dissipation Conditions and Environmental Factors Assessment

1. Installation Space Ventilation: Check if the area around the instrument transformer is sealed and well-ventilated, and whether multiple heat-generating components are tightly packed, creating a heat accumulation effect.

2. Internal Heat Dissipation Structure: Traditional single-sided winding easily forms a "heat focusing area," while using grouped + double-layer winding and thermally conductive adhesive partitioning can effectively accelerate heat dissipation.

3. Ambient Temperature Influence: In high-temperature environments in summer (such as temperatures exceeding 40℃ in southern regions), the combined heat generated by the equipment itself may lead to excessively high temperatures inside the cabinet, exacerbating the temperature rise problem.