Gas insulating material
In general, dry gases at room temperature and pressure have good insulation properties. As an insulating material, gas dielectric also needs to meet the physical, chemical and economic requirements. Air and sulfur hexafluoride gas are commonly used as insulating materials.
Air has good insulation performance, the insulation performance can be restored automatically after breakdown, the electrical physical performance is stable, the source is extremely rich, the application is relatively wide. However, the breakdown voltage of air is relatively low, and the factors such as sharp electrode, short distance, steep voltage waveform, high temperature and high humidity can reduce the breakdown voltage of air. Therefore, compressed air or vacuum is often used to increase the breakdown voltage of air.
Sulfur hexafluoride (SF6) gas is a non-flammable, non-explosive, colorless and odorless inert gas, which has good insulation performance and arc extinguishing ability, far higher than air, and has been widely used in high voltage electrical appliances. Sulfur hexafluoride gas also has excellent thermal stability and chemical stability, but under the action of high temperature above 600℃, sulfur hexafluoride gas will decompose, will produce toxic substances. Therefore, the following aspects should be paid attention to in the use.
(1) strictly control the water content, do a good job in dehumidification and moisture-proof measures.
(2) use appropriate adsorbents to absorb harmful substances and water.
(3) the pressure of sulfur hexafluoride gas in the circuit breaker shall not be too high for liquefaction.
(4) the place where sulfur hexafluoride equipment is placed shall have good ventilation conditions.
(5) necessary and reliable labor protection measures shall be taken for operation and maintenance personnel.