Causes of power transformer faults and treatment methods

A brief analysis of the causes and troubleshooting methods of power transformers during operation has been made. The author believes that correct and reasonable troubleshooting methods can promote the normal operation of transformer equipment. Generally speaking, the fault of the transformer is mainly caused by the power loss in its internal composition, circuit, etc., and external human factors or other aspects may also cause its fault. Therefore, when troubleshooting a power transformer, it is necessary to grasp the cause and prescribe the right medicine to improve its elimination effect.

 Analysis and treatment of common faults

1. Transformer oil deterioration
The oil in the transformer has not been replaced due to long-term use. Rainwater has leaked into it and some moisture has been immersed in it. In addition, the oil temperature in it is often overheated, which easily causes the deterioration of the oil quality. The deterioration of the oil quality will cause the insulation performance of the transformer to be greatly affected, and this situation is very easy to cause the fault of the transformer. If it is a newly put into operation transformer, its oil color will be light yellow, after a period of use, the oil color will become light red. If it is found that the oil color starts to turn black, in this case, in order to prevent current breakdown between the casing and the winding or between the coil winding, it is necessary to take a sample and test immediately. After the test, if the oil quality is qualified, continue to use it. If it is not qualified, the insulating oil will be filtered and regenerated to make the oil quality meet the qualified requirements and be used again.

2. Abnormal internal sound
If the transformer operates normally, the frequency of the electromagnetic humming sound generated in it will be quite stable, and if there is a problem with the operation of the transformer, irregular sounds will occasionally be produced in the transformer, showing an abnormal phenomenon. The main reasons for this situation are: the transformer is overloaded, and in this case, there will be heavy sound inside the transformer; when the parts in the transformer are loose, strong and uneven noise will be generated when the transformer is running. ; The outermost silicon steel sheet of the transformer core is not clamped, it will vibrate when the transformer is running, and it will also produce noise; the screws on the top cover of the transformer are loosened, and the transformer also makes abnormal noises during operation; if the internal voltage of the transformer is When it is too high, the iron core grounding wire will have an open circuit or shell flashover, the shell and the iron core will induce high voltage, and the transformer will also make noise; poor contact and breakdown inside the transformer will cause abnormal noise due to discharge; transformer When there is a short circuit and grounding in the winding, there will be a large short-circuit current in the winding, which will make an abnormal sound; when the transformer generates harmonics and a large-capacity electrical equipment is connected, the starting current generated is large, which will cause abnormal noise in the future.

3. Automatic trip fault
During the operation of the transformer, when an automatic trip occurs suddenly, an external inspection must be carried out to find out the cause of the trip. If after the inspection, it is determined that it is due to improper operation by the operator or due to an external fault, the internal inspection link can be skipped and the power supply can be directly put into operation. If a differential protection action occurs, a comprehensive and thorough inspection of the equipment in the protection range is necessary. It should be noted that there are a lot of flammable substances in the transformer, and internal faults may cause fire, and if it is not handled in time, it may even cause an explosion. There are several factors that may cause a transformer to catch fire: internal faults cause the radiator and casing of the transformer to rupture, and oil is burning and spills from the transformer; under the pressure of the oil pillow, the oil in the transformer flows out and burns on the top cover of the transformer; Damage and flashover of transformer bushings, etc. When these accidents occur, the transformer will spontaneously produce protective actions, and the circuit breaker will automatically open. If the circuit breaker does not automatically open due to some reasons, it must be done manually, immediately stop the air-conditioning equipment and turn off the power to extinguish the fire. Foam fire extinguishers should be used to extinguish the transformer, and sand can also be used to extinguish the fire in an emergency.

Post time: Aug-02-2021