Vacuum circuit breaker
"Vacuum circuit breaker" is named because its arc extinguishing medium and the insulation medium of the contaCT gap after arc extinguishing are high vacuum; It has the advantages of small volume, light weight, suitable for frequent operation and no maintenance for arc extinguishing. Vacuum circuit breaker is 3 ~ 10 kV, 50 Hz three-phase ac indoor distribution equipment in the system and is available for industrial and mining enterprises, power plants and substations as protection and control of electrical equipment, especially suitable for the requirements without oil, less maintenance and the use of frequent operation, circuit breaker can be configured in the cupboard, double tank, fixed for control and protection of high voltage electrical equipment in the Switchgear.
"High voltage vacuum circuit breaker" is named because its arc extinguishing medium and the insulation medium of the contact gap after arc extinguishing are high vacuum. It has the advantages of small volume, light weight, suitable for frequent operation and no maintenance for arc extinguishing. In 1893, Rittenhouse of the United States proposed a simple structure of vacuum extinguishing chamber, and was granted a design patent. The first vacuum switch was made in 1920 by the Swedish company Forga Company. The research results published in 1926 also showed the possibility of dividing the current in vacuum, but due to the small dividing ability and the limitation of vacuum technology and the development level of vacuum materials, it could not be put into practical use. With the development of vacuum technology, the first batch of vacuum switches suitable for cutting capacitor Banks and other special requirements were made in the United States in the 1950s, and the cut-off current was still at the level of 4,000 amperes. Due to the progress in vacuum material smelting technology and the breakthrough made in the research on the structure of vacuum switch contacts, the production of vacuum circuit breakers with 15 kV and 12.5 KVA cut-off current began in 1961.In 1966, we trial-produced 15 kV, 26 KVA and 31.5 KVA vacuum circuit breakers, which enabled the vacuum circuit breaker to enter the high-voltage, high-capacity power system. In the mid-1980s, the breaking capacity of vacuum circuit breakers reached 100 KVA. China began to develop vacuum switches in 1958. In 1960, xi 'an Jiaotong university and xi 'an switching and rectifier factory jointly developed the first batch of 6.7KV vacuum switches with a breaking capacity of 600 amps. Subsequently, a three-phase vacuum switch with a breaking capacity of 1.5 KVA and 10 KVA was made. In 1969, Huagang electronic tube factory and Xi'an high voltage electrical equipment research institute made a 10 KV, 2 KVA single-phase rapid vacuum switch. Since the 1970s, China has been able to independently develop and produce vacuum switches of various specifications.
Vacuum circuit breakers usually have multiple voltage classes. Low voltage type is generally used for explosion-proof electrical use. Like coal mines and so on.
Jp3855-96 general technical conditions for 3.6-40.5kv ac high-voltage vacuum circuit breakers
Technical conditions for ordering 10~35kV indoor high-voltage circuit breakers
It needs to be noted that there is no specific IEC standard corresponding to JB3855 in China, but only the IEC56 ac high-voltage circuit breaker. Therefore, the standards of China's vacuum circuit breakers are higher or stricter than IEC standards in at least the following aspects:
(1) Insulation level: test voltage: IEC China
Power frequency withstand voltage (kV) for 1min
1.2/50 impact withstand voltage (kV) 75(inter polar, pole-to-ground) 84 (inter fracture)
(2) The voltage resistance level of the fracture of the vacuum arcing chamber after the end of the electrical life test: there is no regulation in IEC56.In China, jb38551-96 stipulates that the insulation capacity of the vacuum circuit breaker after the completion of the electrical life test shall be no less than 80% of the initial insulation level, namely power frequency 1min 33.6kv and impact 60kV.
(3) Bounce time of contact closing: there is no IEC regulation, and China's regulation requires no more than 2ms.
(4) Test current for temperature rise test: in IEC standards, the test current is equal to the rated current of the product. It is stipulated in dl403-91 that the test current is 110% of the rated current of the product.
2. Main technical parameters of vacuum circuit breaker the parameters of vacuum circuit breaker can be roughly divided into two aspects: selection parameters and operating parameters. The former is used for user design and selection. The latter is the mechanical characteristics of the circuit breaker itself or motion characteristics, for the operation, adjustment of technical indicators.
The following table is a list of selected parameters, and three kinds of vacuum circuit breaker data as an example.
All parameters listed in the table shall be verified item by item in the type test according to JB3855 and DL403 standards, and the final data shall be subject to the type test report.
By JUCRO Electric(Focus on Vacuum interrupter, Vacuum circuit breaker, Vacuum contactor and switchgear)