What is Difference Between SF6 Switchgear And Air Insulated Cabinet

SF6 cabinet and air-insulated cabinet (HXGN-12 XGN-12 KYN28A-12 KYN61-40.5, etc.) are two common types of electrical switch cabinets. The following is a comparison of their main information:

Insulating medium

SF6 cabinet: SF6 gas is used as the main insulating medium, and medium-voltage components such as busbars, circuit breakers, and disconnectors are concentrated and sealed in a box filled with SF6 gas at a certain pressure.

Air-insulated cabinet: It mainly relies on air as the insulating medium. Except for the arc extinguishing device (such as vacuum or SF6 arc extinguishing chamber), other components in the switch cabinet are in direct contact with the natural atmospheric environment.

Structural features

SF6 cabinet: In order to ensure the relative independence of the insulating gas, it is necessary to weld stainless steel plates into a gas box, and it is equipped with a pressure (density) gauge and a pressure release device. External connections often use solid insulation, such as main busbar connection and primary cable connection, to reduce size and external environmental impact.

Air-insulated cabinet: The structure is relatively simple, usually composed of cabinet, busbar, switchgear, protection equipment, measuring equipment, etc. The insulation performance of each component in the atmospheric environment is guaranteed by reasonable electrical gap and insulation measures.

Performance characteristics

SF6 cabinet

1. Good insulation performance: SF6 gas has high insulation strength, which is more than three times that of air under the same pressure. It can effectively reduce the electrical gap and make the equipment structure more compact.
2. Strong arc extinguishing ability: It has good arc extinguishing performance, which is 100 times that of air. It can quickly extinguish the arc, improve the breaking capacity and reliability of the switchgear, and is suitable for occasions with frequent operations.
3. Little environmental impact: The sealed gas box structure makes it less susceptible to external environmental factors such as humidity, dirt, small animals, etc., and has high operating stability.

Air-insulated cabinet

1. Limited insulation performance: The insulation performance of air is relatively weak and is greatly affected by environmental factors. In harsh environments such as high altitude, humidity, and dirt, the insulation performance will decrease, and it is necessary to increase the electrical gap and take other insulation measures.
2. Various arc extinguishing methods: Vacuum arc extinguishing or SF6 arc extinguishing can be used, but except for the arc extinguishing chamber, other parts mainly rely on air insulation.
3. Good heat dissipation performance: Natural air convection is conducive to heat dissipation, and under normal environmental conditions, it can better meet the heat dissipation requirements of the equipment.

Application scenarios

SF6 cabinet: Suitable for places with high space requirements and harsh environmental conditions, such as urban subways and light rails, high-rise buildings, large enterprises, metallurgy, petrochemicals, mines, and coastal areas.

Air-insulated cabinet: Suitable for places with good environmental conditions, low space requirements, and relatively small loads, such as secondary power distribution systems of general factories, office buildings, residential areas, etc.

Maintenance requirements

SF6 cabinet: The pressure and purity of SF6 gas need to be checked regularly to ensure that there is no gas leakage. If leakage occurs, professional equipment and personnel are required to handle it.

Air-insulated cabinet: Mainly check the contact condition of the electrical connection parts, the aging and contamination of the insulating parts, etc., and clean and maintain them regularly.