The difference between air-insulated and gas-insulated ring main units

Air-insulated ring main unit is generally called semi-insulated ring main unit. Gas insulated ring main unit is generally called fully insulated ring main unit.

The difference is:

1. The distance between phases after air-filled insulation is only 1/3 of that of the air-insulated cabinet, and the size of the switch cabinet is greatly reduced.

2. The insulating medium of the fully insulated ring main unit: sf6, n2 and other gases or their composite gases are used as the insulating medium, and the insulating performance is strong.

3. Electrical clearance: The insulation performance of insulating gas is much stronger than that of air, and the electrical clearance of fully insulated cabinets is much smaller than that of semi-insulated cabinets.

4. Equipment size: Due to the small electrical gap, the size of the fully insulated cabinet is much smaller than the semi-insulated cabinet of the same voltage level, and the floor space is small.

5. Altitude influence: The main circuit components of the fully insulated ring main unit are built into the air-filled compartment, and the pressure is constant, not affected by altitude, especially suitable for high altitude areas. The insulation performance of the semi-insulated ring main unit is directly affected by altitude, standard products are used below 1000m, and higher altitudes require special design

6. Pollution impact: Pollution cannot affect the air-filled compartment of the fully insulated ring main unit, which is suitable for dirty areas. The semi-insulated ring main unit is directly affected by pollution, and special design is required for particularly severe conditions.