What are the hazards of excessive temperature rise in current transformers?

1. Damage and breakdown of insulation materials: Prolonged high-temperature operation accelerates the aging, embrittlement, and cracking of the internal insulation materials (such as epoxy resin and insulating paper) of the transformer, ultimately leading to a decline in insulation performance and potentially causing inter-turn short circuits or primary/secondary side breakdown accidents.

2. Core overheating and magnetic circuit failure: Excessive temperature rise causes a sharp increase in the magnetic flux density of the core, entering a deep saturation state. This results in a surge in hysteresis and eddy current losses, further exacerbating heat generation and creating a vicious cycle that may ultimately burn out the windings.

3. Inaccurate measurement and protection functions: Changes in core characteristics at high temperatures lead to increased transformer ratio errors and phase angle shifts, resulting in inaccurate energy metering. Relay protection devices may malfunction or fail to operate, threatening system safety.

4. Casing Deformation and Safety Hazards: Overheating may cause the transformer casing to bulge, deform, or even crack. Oil-immersed equipment may also experience oil spraying, which in severe cases can damage cable insulation, leading to major accidents such as short circuits, fires, or explosions.

5. Significantly Reduced Lifespan: For every 10°C increase exceeding the allowable temperature rise, the insulation lifespan is reduced by approximately half. Prolonged overload operation will significantly reduce equipment lifespan, increase maintenance costs, and increase the risk of failure.