How to prevent explosion of oil-immersed transformer
Accidents of oil-immersed transformer explosions occur frequently. Because the explosion process of oil-immersed transformers is a relatively slow development process, once the explosion occurs, there will be casualties and huge economic losses. Oil-immersed transformerscan be said to be very scary. Because the operability of the oil-immersed transformer in the explosion process is relatively large, it is a more important place. In order to prevent the explosion accident of oil-immersed transformers, we must start with "preventing".
1. Prevent overload operation of oil-immersed transformer: If the overload operation for a long time, it will cause the coil to heat up, gradually aging the insulation, short circuit between the boxes, short circuit between phases or short circuit to ground and the decomposition of oil;
2. Prevent the aging damage of the core insulation of the oil-immersed transformer: the aging of the core insulation or the damage of the clamping bolt sleeve will cause a large eddy current in the core and the long-term heating of the core causes the insulation aging.
3. Prevent accidental damage to the insulation: When oil-immersed transformers overhaul the hanging core, care should be taken to protect the coil or the insulating sleeve. If any damage is found, deal with it in time.
4. The low-voltage maximum unbalanced current of the oil-immersed transformer should not exceed 25% of the rated value; the allowable range of the power supply voltage change of the oil-immersed transformer is plus or minus 5% of the rated voltage.
5. Ensure good wire contact: poor contact of the internal connectors of the coil, poor connection between the connection points between the coils, the contacts leading to the high and low voltage side bushings, and the fulcrums on the tap-changer, local overheating, insulation damage and short circuit may occur or open circuit. The high temperature arc generated at this time will decompose the insulating oil that generate a large amount of gas, and increase the pressure in the oil-immersed transformer. When the pressure exceeds the protection value of the gas circuit breaker without tripping, an explosion will occur.
6. Maintain good grounding: For low-voltage systems with protective zero connection, (examination. Large) oil-immersed transformer low-voltage side neutral point should be directly grounded. When the three-phase load is unbalanced, current will appear on the zero line. When this current is too large and the contact resistance is large, the grounding point will have a high temperature, igniting the surrounding combustible materials.