Rongzhong Electrical Equipment

Power transformer is an important equipment in power system. Once an accident occurs, it will cause great losses. This paper analyses all kinds of power transformer accidents, finds out the causes, puts forward the methods to deal with the accidents, controls the accident losses within the scope, and minimizes the damage to the system.

In the process of power transmission and distribution, power transformer is the core of energy conversion and transmission. It is the only way of energy source for all walks of life and millions of households. It is also an important and key equipment in the power grid. Safe operation of power equipment is a defense system to avoid major accidents in power grid, and power transformer is the key equipment in this defense system. Serious transformer accidents will not only lead to their own damage, but also interrupt the power supply, causing huge economic losses to society.

Analysis and Treatment of Common Faults

The treatment of transformer automatic tripping. When the transformer in operation automatically trips, the operators should quickly make the following treatment: 1) When the transformer side circuit breakers automatically trips, the control switch of the tripping circuit breaker is operated to the position after tripping, and quickly put into the standby transformer, adjust the operation mode and load distribution, maintain the operation system and its equipment in normal state; 2) Check what kind of protective action the switch belongs to; Whether the action and action are correct or not; (3) Understand whether the system has fault and the nature of the fault; (4) If it belongs to the following circumstances and with the consent of the leader, it can be sent without checking and testing: artificial mis-touch protection trips the circuit breaker; obvious mis-action trips the protection; transformer only operates under low-voltage or time-limited overcurrent protection, while tripping the protection of the transformer's next level equipment fails but does not operate, and the fault has been cut off. Except for the test power transmission, it is only allowed once. _If the main protective action is differential, heavy gas or current fast-break, and there is impulse when the fault occurs, the transformer and its system should be inspected in detail, power outage and insulation measurement should be carried out. It is forbidden to put the transformer into operation until the cause is ascertained. It must be pointed out that no matter whether the system has backup power or not, no forced power transmission is allowed.

The internal sound is abnormal. If the transformer operates normally, the frequency of electromagnetic alternating sound generated by the transformer will be fairly stable, and if the transformer is in trouble, irregular sound will occasionally occur in the transformer, showing abnormal phenomena. Several main reasons for this situation are as follows: the transformer operates under overload, in which there will be heavy noise inside the transformer; when the parts in the transformer are loose, strong and uneven noise will be generated when the transformer is running; when the outer silicon steel sheet of the transformer core is not clamped, vibration will occur when the transformer is running, and noise will also be generated; The screw on the top cover of the transformer loosens, and the transformer makes abnormal noise in operation; if the internal voltage of the transformer is too high, the grounding wire of the iron core will break or flashover, and the high voltage will be induced by the outer shell and the iron core, and the noise will also occur inside the transformer; the bad contact and breakdown will occur inside the transformer, and abnormal noise will occur because of the discharge in the transformer; When grounding, large short-circuit current in winding will produce abnormal sound; when transformer generates harmonics and connects large-capacity electrical equipment, it will cause abnormal sound later because of the large starting current.

Transformer oil deteriorates. Oil in transformer has not been replaced because of long-term use, which leaks into rainwater and soaks in some moisture. In addition, the oil temperature in transformer is often overheated, which easily causes the deterioration of oil quality. The deterioration of oil quality will lead to a great impact on the insulation performance of transformers, which is very easy to cause transformer faults. If it is a newly commissioned transformer, its oil color will be light yellow, after a period of use, oil color will become light red. If the oil color starts to darken, in order to prevent the current breakdown between the shell and winding or between the coil windings, the sampling test should be carried out immediately. After testing, if the oil quality is qualified, it will continue to use. If it is not qualified, it will be filtered and regenerated to make the oil meet the qualified requirements and use again.

Oil level is too high or too low. When the transformer is in normal operation, the oil level should be kept between 1/3 and 1/4 of the oil level meter. If the oil level of the transformer is too low and the oil level is lower than the upper cover of the transformer, it may lead to gas protection and misoperation. In serious cases, it may even cause the lead or coil of the transformer to emerge from the oil, resulting in insulation breakdown. If the oil level is too high, oil spill will easily occur. Long-term oil leakage, low temperature and failure to repair transformer oil leakage in time after discharge are the main reasons for low oil level. There are many factors affecting the change of oil level of transformer, such as the change of operation condition of cooling device, oil seepage of shell, the change of load and the change of surrounding environment. For example, besides oil leakage, the rise or fall of oil temperature directly determines the rise or fall of oil level and the volume of transformer oil. Therefore, when loading oil, the appropriate injection height should be selected according to the local temperature. Transformer oil temperature is affected by load and environmental factors. If the oil temperature changes, but the oil level in the starting standard does not change with it, then the oil level is an illusion. The causes of this situation may be the blockage of the oil standard tube, the blockage of the breathing pipe and the blockage of the ventilation hole of the -proof tube. This requires the on-duty personnel to check the indication status of transformer oil level gauge frequently. If the oil level is too low, it is necessary to find out the reasons and implement corresponding measures.

Rongzhong Electric Co., Ltd., Rongzhong Electrical Equipment, Quanzhou Electrical Equipment Manufacturer, Rongzhong Electric Co., Ltd., Rongzhong Electric Co., Ltd.