Advantages of vacuum circuit breakers
Vacuum circuit breakers are a new stage in the development of switching devices for high voltage distribution networks. The article describes the user characteristics of vacuum circuit breakers in high voltage distribution networks.
The vacuum circuit breaker in electricity is a high-voltage switching device for performing operations of switching on and off electric current in working mode and emergency mode - short circuit mode. In this case, the medium for extinguishing the arc is a vacuum.
Today, the share of vacuum circuit breakers in high-voltage electrical networks up to 35 kV in China is 100%, in Europe — over 65%, in our country it is approaching 60% of all medium voltage switching devices produced.
The undoubted advantages of vacuum circuit breakers are:
- High operational reliability. The degree of failure of vacuum circuit breakers is one order of magnitude lower than traditional circuit breakers (oil, electromagnetic);
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High switching duration and reduced maintenance costs.Without revisions and repairs, the number of disconnections of operating currents from a vacuum breaker reaches 20 thousand, and the number of short-circuit currents is 20 — 200, depending on the values of the currents and the type of breaker. On oil circuit breakers, the revision is carried out after 500 — 100 shutdowns in operating mode and 3 — 10 shutdowns from short-circuit currents. For air circuit breakers this is 1000-2500 and 6-15 trips respectively.
- Fast response and increased mechanical life. The main reason for this is that the travel of the contacts of the arc extinguishing vacuum chamber is no more than 6-10 mm, against 100-200 mm in oil and electromagnetic structures, because the strength of the vacuum for electric breakdown greatly exceeds the electrical strength of oil and air arc extinguishing agents;
- Work autonomy. The vacuum circuit breaker does not require replenishment of the extinguishing medium, which also reduces the operating costs of the vacuum circuit breaker.
- Safety and ease of use. At the same nominal parameters of the switching currents and voltages, the mass of the vacuum circuit breaker is significantly lower than that of other types of circuit breakers. And low drive energy, small dynamic loads and the absence of gas and oil leakage ensure quiet operation, environmental safety and high fire and explosion safety, the ability to work in highly aggressive environments.
It is believed that the achieved quantitative characteristics of vacuum circuit breakers will ensure their promising application, and in the near future the efforts of designers will be directed mainly to increasing the resistance of these switching devices to the influence of the environment and to improving their mechanisms.
See also on this topic: High Voltage Vacuum Circuit Breakers — Design and Principle of Operation