The application of the high-voltage vacuum circuit breaker in our power supply system began in 1978. Its light weight, simple structure, long service life and other advantages were quickly recognized by the power department operation, overhaul and technicians. The quality of the early domestic high voltage vacuum circuit breaker is not stable enough, the on-load voltage is high in the operation process, and there is leakage phenomenon in some vacuum arc extinguishing chambers.

1. The status quo of Chinese high voltage vacuum circuit breaker

The application of the high-voltage vacuum circuit breaker in our power supply system began in 1978. Its light weight, simple structure, long service life and other advantages were quickly recognized by the power department operation, overhaul and technicians. The quality of the early domestic high voltage vacuum circuit breaker is not stable enough, the on-load voltage is high in the operation process, and there is leakage phenomenon in some vacuum arc extinguishing chambers. By the time of Tianjin vacuum Switch Application Promotion Conference in 1992, the manufacturing technology of vacuum circuit breaker has entered the forefront of the same type of products in the same industry in the world, which has become a new historical turning point in the application and manufacturing technology of high voltage vacuum circuit breaker in China.

2. Air leakage in vacuum arc extinguishing chamber

The new generation of high voltage vacuum circuit breaker generally uses the principle of longitudinal magnetic field arc extinguishing and copper and chrome contact material, its purpose is to reduce contact burn loss and improve electrical service life. If the concentricity of the conductive rod is not adjusted properly, the sealing strength of the longitudinal gas line, ceramic, felling and metal will not be stable enough, resulting in air leakage in the vacuum arc extinguishing chamber.

Most of the bellows in the vacuum arc extinguishing chamber are formed by oil pressure of 0.15mm stainless steel. The pollution level, humidity, and salt spray of the application environment of the HV vacuum circuit breaker are not suitable. Harmful gases and condensation cause spotty corrosion of the bellows, resulting in air leakage of the bellows, cover plates and sealing surfaces.

It is an important measure to adjust the concentricity of HV vacuum circuit breaker and choose the proper environment for use and storage.

3. Choose the electrical life of high voltage vacuum circuit breaker reasonably

The electrical life of high voltage vacuum circuit breaker refers to the number of full capacity breaks stipulated in the equipment technical conditions and the actual type test. High voltage vacuum circuit breaker contacts can not be repaired or replaced in application, so it is necessary to require high voltage vacuum circuit breaker to have a high enough electrical life.

The longitudinal magnetic field electrode and copper - chrome contact material are used in the new generation vacuum arc extinguishing chamber. The longitudinal magnetic field electrode reduces the arc voltage (arc energy) under the short-circuit breaking current and makes the arc evenly distributed on the contact surface. Copper-chromium contact material reduces contact burn loss per unit arc energy. The organic combination of these two makes the electrical life of high voltage vacuum circuit breaker have a breakthrough improvement. At present, the performance of the high voltage vacuum circuit breaker rebreaking and closing capacity is relatively high and stable.

Early high voltage vacuum circuit breaker electrical life was only 30 times in our country, the longest operation has more than 20 years. Yet, the high voltage vacuum circuit breaker has not been found in power system because of short circuit opening current's electrical life problem and retires, and did not find that because of short circuit opening current's electrical life is short, causes accidents This fully shows that these high voltage vacuum circuit breakers can basically meet the requirements of the power system for the electrical life of the short circuit breaking current. Therefore, the high voltage vacuum circuit breaker short circuit breaking current electrical life is not the higher the better.

4 Pay attention to mechanical parameter adjustment of HV vacuum circuit breaker

High voltage vacuum circuit breaker has many mechanical parameters, such as closing speed, opening speed, contact travel, contact closing bounce time, contact opening rebound amplitude, etc. These mechanical parameters are set to ensure the technical performance of high voltage vacuum circuit breaker.

The mechanical life of China's high voltage vacuum circuit breaker is generally 10000 ~ 20000, the research work is improving the mechanical life to 30000 ~ 40000 times, electromagnetic operating mechanism is simple structure, reliable performance, convenient adjustment and maintenance, operation personnel accustomed to use and maintenance and widely used; Some places are also accustomed to the use of electric spring operating mechanism. The operating mechanism is the most complex part in the mechanical structure of HV vacuum circuit breaker with the highest precision requirement. The production conditions of most manufacturers are difficult to meet the machining accuracy requirements.

In order to guarantee the reliability of high voltage vacuum circuit breaker, the packaging structure in high voltage vacuum circuit breaker, the operation mechanism and the circuit breaker main body the two separated, concentrated ShengChanCao mechanism from factories production conditions better, then output shaft into the circuit breaker, so the reasonable configuration of mechanical parameters, It is directly related to the technical performance and mechanical life of high voltage vacuum circuit breaker. Ideal mechanical parameter adjustment, very crucial to the mechanical performance of high voltage vacuum circuit breaker. The buffer characteristic satisfied should be the moment when the moving parts contact the buffer, and the buffer provides a small reaction force. With the increase of the buffer distance, the buffer characteristic becomes steeper rapidly, and the separation energy is absorbed as much as possible, so as to achieve the purpose of limiting the tripping rebound and tripping trip.

5 Improve the operation reliability of the HV vacuum circuit breaker

The quality problems of domestic materials, components and standard components as well as traditional product design concepts lead to its mechanical reliability and mechanical life being less than ideal.

(1) grasp the basic structure of vacuum circuit breaker, familiar with its technical performance indicators, reasonable choice of conditions of use, close contact with manufacturing information, accurate application of high voltage vacuum circuit breaker advanced technical functions;

(2) Do a good job in mechanical parameter debugging of HV vacuum circuit breaker, strict mechanical parameter index requirements, to ensure its basic function;

(3) Standardize the management and storage of spare parts, and ensure the consistency, universality and reliability of technical performance indexes and quality of spare parts;

(4) Make operation record and accident analysis of HV vacuum circuit breaker, summarize experience, cooperate with manufacturing department, and continuously improve the advanced nature, reliability and economy of vacuum circuit breaker.

6 Temperature rise of HV vacuum circuit breaker

The circuit resistance of high voltage vacuum circuit breaker is the main heat source that affects the temperature rise, and the circuit resistance of arc extinguishing chamber usually accounts for more than 50 of the circuit resistance of high voltage vacuum circuit breaker. The contact gap contact resistance is the main component of the loop resistance of the vacuum arc extinguishing chamber, because the contact system is sealed in the vacuum arc extinguishing chamber, and the heat generated can only dissipate to the outside through the dynamic and static conductive rod.

The static end of the vacuum arc extinguishing chamber is directly connected with the static support, and the moving end is connected with the moving support through the conductive clip and soft connection. Although the upward movement of the moving end is conducive to the heat dissipation of the moving end, the highest temperature rise of the HV vacuum circuit breaker is mostly concentrated in the lap part of the moving conductive rod and the conductive clip due to the many links and long thermal conduction path of the moving end. In practical application, effective use of the components in the static end that are conducive to heat dissipation, force the contact clearance heat to be exported from the static end, and split the heat from the moving end, is an effective measure to solve the problem of high temperature rise of HV vacuum circuit breaker.

The superior technical application characteristics of high voltage vacuum circuit breaker have been widely recognized in power departments. The related problems can be used for reference in the practical work. In order to make full use of and better play the technical advantage of high voltage vacuum circuit breaker, it is very beneficial to improve the overall equipment level of rural power grid.