What to Do If the Temperature of a Dry-Type Transformer Rises Sharply During Operation

We occasionally encounter a problem: the temperature of a dry-type transformer surges sharply suddenly during operation. What causes this phenomenon, and what hazards will it bring?

The temperature of a dry-type transformer will rise gradually during normal operation, which is a slow and steady process generated by the equipment’s power output. However, in some cases, the temperature spikes drastically, disrupting the transformer’s performance and triggering frequent faults.

Such faults of dry-type transformers must never be taken lightly, as they may lead to explosions and fires. How should we identify the root causes and adopt corresponding solutions when this occurs?

1. Inter-laminar short circuit of core silicon steel sheetsExternal mechanical damage, insulation aging and other factors can damage the insulation between silicon steel sheets, resulting in high eddy current and local overheating.

2. Poor contact of tap-changerInsufficient contact pressure on tap-changer contacts or dirt accumulated on contact surfaces will lead to high contact resistance and heating at joints. The poor contact and overheating are more likely to occur after tap position switching or under transformer overload operation.

3. Coil inter-turn short circuitInter-turn short circuits reduce the effective number of winding turns and form closed short-circuit circulating currents, generating extremely high temperatures at the short-circuit points. Severe inter-turn short circuits will raise the overall temperature, and the oil at the faulty spot will produce a gurgling sound.