Brief introduction of UHV circuit breaker

There are many kinds of UHV circuit breakers, which are divided into oil circuit breakers, air (vacuum) circuit breakers and SF6 circuit breakers according to different fire extinguishing media. Sulfur hexafluoride (SF6) circuit breakers are usually used for EHV circuit breakers. Only in some areas, due to the cold weather, sulfur hexafluoride gas may liquefy and use compressed air switch. In recent years, adding a small amount of other gases into sulfur hexafluoride gas to reduce the liquefaction temperature can still be used in cold regions. SF6 circuit breaker uses SF6 gas as arc extinguishing and insulating medium. Its characteristics are: low working pressure and high safety and reliability; In the process of arc blowing, the gas circulates in the closed system and is not discharged into the atmosphere, so there is no fire danger. Because SF6 gas has excellent arc extinguishing and insulation performance, SF6 circuit breaker has many advantages: high breaking voltage, strong breaking ability, allowing continuous short-circuit current breaking for many times, suitable for frequent operation, no reignition or reignition of capacitive current breaking, no interception of inductive current breaking, etc. In recent years, it has replaced the compressed air switch in the field of high voltage and ultra-high voltage; It is the most important circuit breaker in UHV field. SF6 circuit breakers require higher materials, processing technology and assembly, especially higher air tightness, and the annual air leakage rate is generally less than 65438 0%. Therefore, factories producing SF6 circuit breakers need special purification and assembly workshops, gas recovery and treatment devices, SF6 leak detectors, micro-water detectors, adsorbents for adsorbing fluoride and moisture, and drying equipment.

In addition to completing the tasks of general high-voltage circuit breakers, EHV circuit breakers also need special measures (such as opening and closing resistors) to minimize the operating overvoltage during opening and closing, so as to reduce the insulation level and cost of lines and substation equipment.