1. Causes of common faults of transformer
1.1 transformer oil leakage
The main reasons are as follows: a. the process quality of the sealing material is poor, the design and manufacturing process of the sealing structure are relatively rough, and there is no trial assembly of the transformer before leaving the factory. b. Poor cutting and blanking process quality and low welder level lead to poor welding quality, and false welding phenomenon and poor back welding result in unreasonable welding structure. c. Purchasing personnel do not know the relevant technical parameters, and purchase non-standard parts at will. d. Because the professional team management is not in place and the technology is not up to standard, the oil leakage rate of transformer installation and overhaul is more than 2%. e. In the process of assembly, if the sealing gasket is pressed too tightly, the flange and cover are too tight, and the sealing surface is not equal, the assembly procedure will not meet the professional standards.
1.2 technical treatment for overheat of current carrying joint
The overheat of current carrying connector of transformer is also known as "poor contact overheat". The fault mainly occurs in the contact between the dynamic and static contacts of the isolation switch, the connection between the lead wires, the lead connector and the joint of the primary equipment. There are three main reasons for the heating of transformer current carrying element joint: A. in order to prevent oxidation and external pollution, neutral Vaseline will be coated on the conductive surface and covered with thin paper. If it is not removed during installation, the contact resistance will be increased, resulting in poor contact and heating. b. The contact surface of the switch terminal board is not flat enough, the thickness of the transition plate between the knife switch and the lead wire is not enough, and the diversion surface of the transition plate is installed reversely, which will lead to insufficient contact area and cause heating. c. Due to the action of damp heat, salt spray and industrial atmosphere, electrochemical corrosion is produced. The corrosion product is insulator, which causes the surface resistance to increase and causes heating.
1.3 transformer winding fault
During long-term operation, the insulation part of transformer winding is prone to aging, fracture and other phenomena, and the electrical strength will gradually decrease; when the transformer is working, it is easy to deform the insulation part of the winding due to repeated short-circuit impact; when the voltage fluctuates greatly, the insulation layer is easy to be broken down; the winding technology is unscientific, and the mechanical strength is not up to the requirements The insulation layer is damaged; the insulation oil of the transformer mixed with water or impurities will also lead to the oil temperature is too high, the voltage is too high, and the insulation layer is broken down; the transformer's lightning protection facilities are not perfect, grounding fault, phase short circuit, broken wire and so on will cause the aging and breakdown of the insulation layer. It needs to be solved according to the actual situation.
2. Common fault analysis of power transformer
The faults with high frequency are mainly manifested as follows: first, in rainstorm and lightning weather. There are problems in the power transmission process of power transformer, which leads to the power can not be transported out normally. Second, in the process of power transmission. The voltage display of power transformer is unstable, resulting in individual voltage rise. Cause the equipment to burn down. Third, when the pressure of the power transformer is too high, the fuse will be burned out, causing the power system to malfunction. In addition, the terminals are easy to burn out.
Cause the high voltage bushing to be wrong. Fourth, the noise problem of power transformer. Some poor quality power transformers in the use process due to excessive sound, resulting in the occurrence of safe airway fuel injection incidents, resulting in power transmission interruption, pollution of the environment. Fifth, when the power transformer is cooling, the temperature controller has problems, so that the temperature can not normally drop, but continue to rise, leading to the occurrence of fire.
3. Discussion on routine maintenance measures of transformer
3.1 pay attention to the appearance cleaning and maintenance of transformer
If the transformer is covered by dust for a long time, it will affect the heat dissipation function. Poor heat dissipation will reduce the insulation effect of the transformer, which is easy to cause transformer failure and reduce the service life of the transformer. Pay attention to the clean maintenance of transformer appearance. Especially when the working load of the transformer is heavy, it can help the transformer heat dissipation and prolong the service life. When the transformer works in the outdoor harsh environment, it is necessary to prevent the oxidation of the transformer shell. Timely anti-corrosion treatment shall be carried out to protect the transformer shell.
3.2 strengthen the daily inspection and supervision of transformers
The daily supervision work of transformer is very important, such as abnormal noise, oil leakage, oil leakage and other faults, if you can make a response at the first time, the damage degree of transformer can be greatly reduced. Arrange special personnel to inspect and supervise the transformer every day. Check whether the working state of the transformer is normal. In addition to observing the operation of the transformer by eye observation and ear listening, the operation of the transformer can be checked. It is also necessary to measure whether the current, voltage, three-phase load and other parameters of the transformer are normal.
3.3 effective monitoring of transformer oil level
The transformer oil level monitoring can observe the size of the power load, the oil level will change with the size of the power load, too high or too low oil level will have a certain danger. The oil level will rise when the transformer is overloaded or the oil temperature is too high. At this time, the overall pressure of the transformer increases, once the sealing system has problems. It will cause oil leakage, which is a great potential safety hazard in the process of transformer operation. Oil leakage and oil leakage will damage the internal insulation structure of transformer, and the insulation effect is poor. It will also cause heat dissipation problems and bring hidden dangers to the operation of the transformer. Therefore, it is necessary for the staff to strengthen the effective monitoring of the oil level of the transformer. Replenish in time in case of lack of oil. When there is too much oil, proper oil should be drained and qualified transformer oil should be selected to protect the internal organization of transformer.
3.4 regularly repair and maintain the transformer
The transformer must be repaired and maintained regularly to ensure the safety of the transformer. The accumulated work of transformer will inevitably lead to faults and problems. Regular maintenance can not only solve the fault in time, but also prolong the service life of transformer and enhance the safety and stability of operation. Regularly check the gas content in the transformer oil, judge whether the transformer oil is deteriorated, and test the physical properties of the transformer oil. Make it keep good insulation. Regularly check the insulation and grounding of transformer bushing, coil, lightning rod and other parts. Check the grounding resistance in time and check whether the parameters are normal. Check whether the connection between bushing and terminal is normal. Check the operation and ventilation of the transformer cooling system, check the opening and closing of each valve position, and reasonably formulate the inspection mechanism and result registration. So that the shift personnel and maintenance personnel can timely understand the working condition of the transformer. Regularly arrange overhaul and minor repair of transformer to eliminate faults and potential hazards in time.
The stable operation of transformer plays an important role in the stability of the whole power system. Transformer in the actual use process will inevitably appear a variety of faults, timely and rapid resolution of the fault, can effectively reduce the adverse impact of power failure on people's social life and economic development. In addition, strengthening the daily maintenance of the transformer can greatly improve the security of the power system.