Problems with the isolating switch and maintenance and repair methods

Because the outdoor isolation switch is a kind of electrical equipment that is completely exposed to the atmosphere and is most directly and severely affected by environmental and climatic conditions, its operating conditions are relatively harsh, and it is prone to mechanical or electrical failure. With the aging of equipment and the increase of power load, power failures caused by the disrepair of the isolation switch and some manufacturing defects continue to occur, and are on the rise, which seriously threatens the safe operation of the power system.

1. Isolation switch porcelain bottle breakage problem

Isolation switches often have porcelain bottle breakage faults on 220kV grade lines. Some have developed into major accidents, which have great impact. The breakage of pillar insulators and rotating porcelain bottles has occurred over the years. Some are old products that have been in operation for many years, and some have just been put into operation. Only a new product for more than a year. Insulator breakage is related to the quality of the electric porcelain factory, and also related to the overall quality of the isolating switch, the uneven casting of the insulator, and the problem of cement binding. In addition, the quality inspection methods are not strict, leaving hidden dangers to the operation. Insulators with defects and hidden dangers are not detected. After being assembled into products, they pose a great threat to safe operation. In addition to supporting insulators, the failure of rotating insulators also occurs from time to time. Rotating insulators are mainly subjected to torsion during operation. Porcelain bottle breakage accidents cannot be effectively prevented.

2. Problems with the isolation switch operating mechanism

When the isolating switch is put into production at the factory or after installation, the closing and closing operation is still normal. But after a long time, some problems will occur after one or two years. The operation failure is first of all a mechanical transmission problem. The early use of the mechanism box is easy to enter the water, condensation and moisture. The waterproof bearing of the rotating bearing is poor, and it is impossible to add lubricating oil. It does not operate for a long time, the mechanism is stuck, the bearing rust is dead, and the forced operation often leads to Parts are damaged and deformed. In addition, the transmission structure design of the product is unreasonable, and the operational resistance is also an important reason. In some products, the conductive rod closing limit is improperly matched with the motor, which causes the turbine to crack during operation. Some of the knives of the isolating switch drive shaft are connected with the vertical drive shaft, and a semi-cylindrical anastomosis structure is adopted. In the electric operation, the relative displacement of the semi-cylindrical deformation occurs, so that the closing and closing is not in place. Also, due to the corrosion of the grounding blade, the shaft pin is broken and cannot be operated. In addition, there are auxiliary switch problems, including poor switching or poor contact of the contacts, resulting in malfunction of the electric operation.

3. Isolation switch conduction loop heating problem

1 When the isolation switch is operated for a long period of time, the equipment will tend to age, and the static contact finger compression spring characteristics will deteriorate. It may also be that the static contact finger single-contact contact clamp spring is loosely deformed, and the clamping force is insufficient to cause part of the finger to move. The contact does not touch, so that the contact surface of the contact finger and the moving contact is reduced, the static and dynamic contacts have dirt, and the contact resistance of the material is easily oxidized and rusted after long-term operation, and the burnt pit is obvious on the finger. 2 The closing is not in place or the scissors clamp structure is poorly clamped. There is a deviation in the closing angle, resulting in insufficient contact surfaces, insufficient fastening of the connecting bolts or excessive bolt breakage. 3 peaks in the summer when the load is large, frequent fever. 4 is in a stable and heavy load all year round.

4. Ways to improve the operation, maintenance and overhaul of the isolating switch

For the various problems existing in the isolating switch, in the maintenance of the annual switch unit of the isolating switch, the maintenance of the 220kV busbar disconnecting switch with the electrolytic head is strengthened, and should be included in the plan and regulations. For the replacement of the switch mechanism contact spring component or the replacement of the entire static contact should be based on the shortened cycle of aging, if the isolation switch is older, it is best to plan to replace it. During the overhaul, the resistance of the isolating switch conductive circuit should be measured. It is found that there is a fever abnormal site, or components with overheating traces should be replaced in time. In particular, the resistance of the contact surface of the static and dynamic contacts is the main cause of heat generation. The measurement of the resistance of the conductive loop is also a means of verifying the quality of the inspection, and the qualification is the condition for the operation of the maintenance equipment. At the same time, it is necessary to strengthen the inspection of the joints. The online temperature monitoring of the joints is the main means to find the heat of the joints. The heat of the joints of the equipment is relatively hidden. The inspection is more difficult. The online temperature measurement should be further strengthened. Consider the temperature measurement once every quarter. At present, temperature measurement is combined by three methods: universal temperature measurement, key temperature measurement, and suspected temperature measurement. Generally, the temperature is measured once a year and in summer; the key temperature measurement is to periodically measure the temperature where the temperature rise exceeds a certain value; the temperature measurement at the suspect point is to measure the temperature of the large load point and the possible heat when the load is large. . At the same time, it is necessary to establish relevant regulations for contact overheating. The superior department and the regulations do not stipulate how many temperatures report general defects, major defects, which level to report to, and whether there should be power outages. For example, it is possible to report a major defect when the temperature rises above 65 °C, and the temperature rise is reported to be a general defect between 40 ° C and 65 ° C, and the key monitoring is performed once a week. At the same time, it should be noted that many of the isolating switch contactors have no protective cover, which is prone to accidental collision during operation, and should be considered to be complete. Some isolation switch terminal block numbers are illegible and need to be rewritten after verification. Pay attention to the fastening of the terminals during operation and maintenance. The sealing ring of the door is easy to age and should be replaced frequently. A good seal can reduce the maintenance workload.