Transformer accident detection and measures
An abnormal sound inside the transformer. The abnormal sound inside the transformer may have the following reasons: severe overload causes a heavy “click” inside the transformer; due to poor contact or breakdown point inside, the inside of the transformer may “吱吱” or “噼啪” Discharge sound; due to loose parts of the transformer top cover connecting the shaft bolt, the transformer core is not clamped, causing the silicon steel sheet to vibrate, which will emit strong noise; when there is grounding or short-circuit fault in the power grid, a large current flows in the winding, Strong noise is emitted; when the transformer is connected to a large power equipment or a device capable of generating harmonic currents, the operation of the equipment may cause the transformer to emit a "wow" sound; due to the resonance of the iron core, the transformer may be rough and thin; If the primary voltage is too high and the current is too high, abnormal noise will occur; due to overvoltage, winding or lead-out discharge to the outer casing, or the core grounding wire is disconnected, causing the iron core to discharge to the outer casing, the transformer will emit a discharge sound.
Emergency measures: When it is found that the transformer makes an abnormal sound, it should judge its possible cause according to the above analysis, and take emergency measures in a targeted manner. If the abnormal sound emitted inside the transformer is caused by loose parts or breakdown of the winding wires, it should be immediately powered off to prevent the accident from further expanding.
The transformer oil level is too high or too low. Under normal circumstances, changes in oil temperature can change the oil level. As the oil temperature changes, the oil level also appears correspondingly - a change in the range. However, under abnormal conditions, abnormal oil level changes may occur due to faults such as oil seepage and water seepage and other accidents. Second, the change in oil temperature is related to conditions such as load conditions and ambient temperature. When the oil level change is inconsistent with these factors, it may be a false oil level. The reason for the occurrence of the false oil level: The oil standard pipe is blocked; the vent hole of the explosion-proof pipe is blocked. In addition, if the oil level is too high, it will cause oil spill; if the oil level is too low, it may cause the internal lead wire of the transformer or even the coil to be exposed, resulting in internal discharge.
Treatment method and emergency measures: The gas relay protection will release its trip circuit to prevent false tripping. On-duty electrical equipment operators should always check the oil level gauge indication and find that the oil level can be drained when the oil level is too high; when the oil level is too low, the oil should be replenished in time. If it is caused by oil leakage from the transformer, power outage maintenance and other emergency measures should be taken. When it is found that the oil pillow or the explosion-proof pipe is abnormally injected, the power supply of the transformer should be cut off immediately to prevent the expansion of the fault and the accident.
The transformer oil quality deteriorates or the oil temperature suddenly rises. In working condition, the main function of transformer oil is cooling and insulation. When it is overheated for a long time or the shell enters the water, it absorbs moisture and deteriorates the oil quality. Observing the oil mark will find that the oil color is abnormally deepened or blackened; after sampling, it can be found that the oil contains carbon particles and water, the acid value is increased, the flash point is lowered, and the insulation strength is lowered. In this case, it is easy to cause a breakdown discharge between the winding and the outer casing, causing a serious accident. When the transformer is operating normally, if the oil temperature suddenly rises, it is often the cause of overheating inside the transformer. The iron core is on fire, the winding is short-circuited between turns, the internal screws are loose, the cooling device is faulty, and the severe overload of the transformer may cause the oil temperature to suddenly rise.
Solution and emergency measures: It is found that the oil color is abnormally deepened or blackened, and the insulating oil needs to be regenerated and treated excessively; the oil temperature suddenly rises due to load factors, and the load can be appropriately reduced or adjusted; oil caused by other abnormal conditions If the temperature suddenly rises, you should immediately power off and perform a comprehensive overhaul of the transformer.
The transformer caught fire. When a fault occurs inside the transformer and it is not processed in time, it may catch fire and cause a fire. When the transformer is on fire, the insulating oil in the fuel tank burns and turns into gas, causing the fuel tank to burst, and the burning insulating oil is sprayed outside the transformer, which will cause equipment damage and property damage. Internal or external short-circuit of the transformer conductor, severe overload, lightning strikes or external fire sources moving into the transformer may cause the transformer to catch fire.
Emergency measures: a. Strengthen the operation and management of the transformer, try to control the oil temperature in the transformer not to exceed 85 °C; regularly check and test the electrical performance of the transformer, and regularly test the deterioration of the oil. b. The high-voltage and low-voltage sides of small-capacity transformers should have over-current protection links such as fuses; large-capacity transformers should be equipped with gas protection and differential protection as required. When the high voltage is protected by a fuse, the transformer rated voltage below 100KVA is selected 2-3 times of the rated current of the transformer. For transformers above 100KVA, the fuse is selected at 1.5-2 times the rated current. c. The room where the transformer is placed is a first-grade refractory building; it should have good ventilation, the maximum exhaust air temperature should not exceed 45 °C, the inlet and exhaust air temperature difference should be controlled within 15 °C; indoors should have oil retaining facilities and oil storage pits Do not install two transformers in the same room according to safety requirements. d. Always check the transformer load and the load must not exceed the safety management regulations. e. Transformers introduced by overhead conductors shall be equipped with lightning arresters in accordance with the regulations, and lightning protection devices shall be inspected before the thunderstorm season. f. Set up special personnel to maintain the transformer, and have inspection and inspection systems and records. Keep the transformer clean, safe and economical, and clean the working environment.