What is a vacuum circuit breaker
I. Overview
The "high voltage vacuum circuit breaker" is named because the arc extinguishing medium and the insulating medium in the contact gap after arc extinguishing are both high vacuum; It has the advantages of small size, light weight, being suitable for frequent operation and extinguishing without maintenance, and is widely used in distribution network. A Brief History of Development In 1893, Rittenhouse of the United States proposed a vacuum interrupter with simple structure and obtained a design patent.
in p>192, the Swedish foga company made the vacuum switch for the first time. The research results published in 1926 also showed the possibility of breaking current in vacuum, but it could not be put into practical use because of its small breaking ability and the limitation of the development level of vacuum technology and vacuum materials.
with the development of vacuum technology, the United States made the first batch of vacuum switches suitable for cutting off capacitor banks and other special requirements in the 195s, and the breaking current was still at the level of 4 kA. Due to the progress of vacuum material smelting technology and the breakthrough in the research of vacuum switch contact structure, in 1961, the production of 15 kV vacuum circuit breakers with breaking current of 12.5 kA was started.
China began to develop vacuum switches in 1958. In 196, Xi 'an Jiaotong University and Xi 'an Switch Rectifier Factory jointly developed the first batch of vacuum switches with 6.7 kV and 6 A breaking capacity. Then a three-phase vacuum switch with 1 kV and breaking capacity of 1.5 kA was made.
In p>1969, Huaguang Electron Tube Factory and Xi 'an High Voltage Electrical Apparatus Research Institute made a 1 kV and 2 kV single-phase fast vacuum switch. Since 197s, China has been able to independently develop and produce vacuum switches of various specifications.
vacuum circuit breakers can usually be divided into multiple voltage levels. Low-voltage type is generally used for explosion-proof electrical use. Like coal mines and so on.
ii. working principle
the working principle of a vacuum circuit breaker is that when the moving and stationary contacts are switched off under the action of the operating mechanism, an arc is generated between the contacts, and steam is emitted from the contact surface at high temperature. Because the contacts are designed in special shapes, a magnetic field is generated when the current passes, and the arc moves rapidly along the tangent direction of the contact surface under the action of this magnetic field, and some metal steam is condensed on the metal cylinder (shield), and the arc naturally crosses zero.
III. Features of vacuum circuit breaker
① The contact opening distance is small, and the contact opening distance of 1KV vacuum circuit breaker is only about 1mm, so the operating work of the operating mechanism is small, the stroke of the mechanical part is small, and its mechanical life is long.
② The arcing time is short, and it has nothing to do with the switching current, generally only half a cycle.
③ After arc extinguishing, the medium in the contact gap recovers quickly, and the fault performance in the near area of breaking is good.
(4) due to the small wear during current interruption, the electrical life of the contact is long, with full capacity of 3-5 times and rated current of more than 5 times, and the noise is low, which is suitable for frequent operation.
⑤ small size and light weight.
⑥ Suitable for interrupting capacitive load current.
vacuum circuit breaker parameters
voltage parameters: rated voltage kV1；; The highest voltage is 11.5
Insulation level: power frequency withstand voltage between electrodes, electrode to ground 42 and fracture 48; Impact withstand voltage between poles, pole-to-ground 75 and fracture 84.
current parameter rated current A125125315；; Rated short circuit interrupting kA231.54；; Rated peak withstand current kA581；; 4S short-term withstand current kA231.54；; Rated short-time closing current (peak value) kA581；; Rated breaking current of single capacitor bank A638；; Rated back-to-back capacitor bank interrupting current A44；; The rated short-circuit breaking current of service life is 553 times; Mechanical life is 1
other
rated operation sequence is -.5s- on-off -18s- on-off-off -18- on-off times are not more than 6. Equipped with operating mechanism CD or CT mechanism.