Question

In gas insulated switchgears _____ gas is used at an above pressure.
1. SF₆
2. CO
3. CO₂
4. NO

Answer 1

Correct Answer - Option 1 : SF₆

Explanation:

Gas Insulated Assembly (GIS):

• The substation, assembled by gas-insulated switchgear, is popularly known as a gas-insulated metal-enclosed substation (GIMES).
• In gas-insulated medium-voltage switchgear, vacuum technology is used for interrupting purposes,s and SF₆ gas is used as insulation material.
• Although for both interruption and insulation, SF₆ gas is used in many medium voltage GIS systems. But for such equipment rated SF₆ gas pressures are different for interruption and insulation.
• SF₆ gas pressure for insulating purposes is generally kept below 2.5 bar whereas SF₆ gas pressure for interrupting purposes is ranged from 5 bar to 7 bar.
• As vacuum technology is not available for high voltage, so for GIS or gas-insulated switchgear system above 72.5 kV, only SF₆ is used both for interruption medium and insulation.