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CheckoutVacuum and gas circuit breaker - comparison
| Vacuum switch | SF6 circuit breaker |
| 1.) Dielectric strength at the level of medium voltage classes in vacuum is much higher than that of elegas. | 1.) Medium voltage SF6 circuit breakers have more varieties than vacuum circuit breakers. |
| 2.) The operational reliability of a vacuum arc extinguishing chamber is much higher than that of an electric gas arc extinguishing chamber. | 2.) SF6 arcing at shutdown is based on the generation of a high-temperature arc of conductive plasma. |
| 3.) When using modern technologies in the production of vacuum switching equipment and qualitatively selected contact materials, the task of insulation coordination is solved with a high degree of reliability. | 3.) For medium voltage SF6 circuit breakers, depending on the type of circuit breakers, annual inspections are required: small every five years and, in any case, every ten years. And even if the circuit breaker has been used only occasionally in 10 years, the entire arc chute is repaired. |
| 4.) Environmental cleanliness is an important factor in the use of this or that type of technology. Vacuum switches do not require maintenance until the end of 10,000 switching cycles. This means that under normal operating conditions, there is no need for lubrication or adjustment during the entire more than 20-year operation period. | 4.) When the current in the SF6 chamber is switched off, the electric arc causes decomposition of the SF6 gas. In this case, lower gaseous sulfur fluorides SF, SF4 and metal fluorides are formed, the particles of which are absorbed on the surface of the contact system and other parts of the chamber. SF6 itself is not a toxic gas, but its gaseous decomposition products, when interacting with water vapor, can cause toxic poisoning for maintenance personnel during technical inspection or damage to the circuit breaker. In this regard, SF6 circuit breakers are not environmentally friendly and their disposal requires additional funds. |
| 5.) Dielectric strength of deep vacuum (vacuum 10+7 bar.) for medium voltage levels is higher than that of other dielectric materials. The use of insulating synthetic materials in the vacuum switch is practically excluded (electrically insulating ceramics are used). The phase poles of the circuit breaker are isolated from ground by a standard support insulator and insulating rods. | 5.) The SF6 arc chute, unlike the vacuum one, consists of insulating synthetic parts and rubber gaskets, due to the presence of which the probability of explosion and fire hazard in case of damage to the switching device is very high. |
| 6.) Arc extinguishing in a vacuum chamber has a completely different principle, based on the formation of metal vapors and their condensation on the surface. At the same time, there are no toxic emissions and the disposal of vacuum chambers is environmentally friendly. | 6.) In the event of an emergency, an electric arc can ignite synthetic materials if the arcing medium (SF6) is lost, there is always a risk of explosion due to the failure of the arc leading to an emergency electric arc between three poles (three-phase short circuit) and instantly materials. |
| 7.) Vacuum chambers do not have rubber gaskets. Sealing of the arc-extinguishing medium in the vacuum chamber from the environment is made by high-quality argon welding, which does not lose its sealing properties during the entire operational period. Such compounds are not prone to aging. At the same time, the cleanliness of the vacuum is maintained throughout the entire service life. Vacuum chambers that have not been used retain their performance for more than 20 years. Thus, readiness for switching is not limited by idle time. | 7.) For SF6 circuit breakers, the arcing medium of the switching chamber is sealed from the environment with various rubber gaskets or epoxy compounds that are prone to aging and deterioration of dielectric and sealing properties during the life of the circuit breaker. The dielectric properties of the SF6 gas are reduced due to the accumulation of decomposition products in the switching chamber with an increase in the number of switchings, also during the entire service life. |
| 8.) Operational reliability of the switching chamber is 24 years. | 8.) Operational reliability of the switching chamber 2.5 - 8 years. |
07/08/2023 17:38:12
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