Electric gas switches: Advantages and disadvantages of application

Electric and gas switches are mainly used for high voltage. Due to the above-mentioned characteristics and properties of elegas, such switches are used for switching tasks related to high and ultra-high voltage.

✅ Advantages; and ❌ Disadvantages; electric and gas switches:

✅ The main advantage of electric gas switches is excellent insulation, extinguishing arc, physical and chemical properties of SF6 gas;

❌ Poor-quality joints in switch housings lead to SF6 gas leaks;

✅ Elegas is non-flammable and chemically stable. Gas decomposition products are not explosive, that is, there is no risk of ignition and explosion.

❌ Continuous monitoring of devices is required;

✅ Due to the dielectric strength of SF6, the electrical gaps are very small;

❌ Elegas is to some extent a suffocating gas;

✅ Outdoor ELV circuit breakers for extra high voltage require fewer breakers per pole than air insulated circuit breakers and oil circuit breakers. External elegas switches are simple, inexpensive, they are compact and do not require maintenance;

❌ In case of leakage from the switch housing, elegas, being heavier than air, fills the surrounding room and can lead to suffocation of service personnel. At the same time, it is not poisonous;

✅ Their work is not affected by changes in atmospheric conditions;

❌ The gas in which the arc was extinguished is poisonous, and you should try not to inhale it;

✅ They work silently, without making the kind of sounds that air-insulated switches make during operation;

❌ The internal parts of the electric gas switch require thorough cleaning during preventive maintenance in a clean and dry environment. It is necessary to remove Teflon dust and sulfides;

✅ There is no need for frequent replacement of contacts - the duration of the arc is short due to its good quenching by SF6 gas, and therefore contact erosion is reduced. Contacts are also not subject to oxidation.

❌ Special equipment is required to transport elegas, transfer it or maintain gas quality;

✅ Since no carbon particles are formed during the existence of the arc, there is no decrease in the dielectric strength of SF6. Minimal maintenance. The switch may require maintenance once every 4-10 years;

❌ Deterioration of the quality of SF6 affects the operation and reliability of electric and gas switches;

✅ Hermetic design prevents gas contamination with moisture, dust, sand, etc. No need for an expensive compressed air system, as in the case of air-insulated circuit breakers;

✅ The same gas is returned to the system, reducing the total need for SF6 gas;

✅ There are no overvoltage problems. The arc is extinguished at a natural zero current, without the amplitude limitation of the current and the associated overvoltage that occurs between the terminals of the switch;

✅ The electric and gas switch can perform various tasks without any problems, such as blocking short-circuit failures, disconnection of power transmission lines that do not have a load, capacitor switching, reactor switching, etc.;

✅ Good load limits. For the same conductor size, due to the high thermal conductivity of elegas, the maximum current load of elegas switches is approximately 1.5 times higher than that of switches with air insulation;