SF6 Load Break Switch SF6 LBS 35KV VCB For RMU Panel
Product Introduction
The SF6 load switch is a switchgear with a rated voltage of 12KV. It uses SF6 gas as the arc extinguishing and insulating medium. There are three positions for closing, opening and grounding inside the switch. It has small size, easy installation and use, and strong environmental adaptability.
Physical properties
SF6 is a relatively heavy gas. Under the same conditions, its density is 5 times that of air. The relationship between pressure and temperature follows the ideal gas law. The critical temperature is the highest temperature at which SF6 gas liquefies, and the critical pressure represents the gas pressure required for liquefaction at this temperature. SF6 can remain gaseous only when the temperature is higher than 45℃. Under normal conditions of use, it has the possibility of liquefaction, so SF6 cannot be used at too low temperature and too low pressure.
Electrical characteristics
SF6 is a medium with high dielectric strength. Under a uniform electric field, the dielectric strength of SF6 is about 2,5~3 times that of air at the same pressure, and its dielectric strength is equivalent to that of transformer oil at 3 atmospheres. Practice has proved that mixing a small amount of sulfur hexafluoride gas in the air significantly increases the insulation strength of the air; on the contrary, adding a small amount of air to the sulfur hexafluoride gas will significantly reduce the insulation strength of the sulfur hexafluoride gas. Due to the high dielectric strength of SF6, for circuit breakers with the same voltage level and similar breaking current, the number of SF6 series fractures is less. For example, the LR-220 SF6 circuit breaker developed in my country has a single fracture voltage of 220KV. ; Another example is the 500KV oil-less circuit breaker with 6 to 8 fractures, while the SF6 circuit breaker has only 3 to 4 fractures. The corona onset voltage of SF6 is much higher than that of air, and the dielectric strength has nothing to do with the frequency of the applied voltage. However, attention should be paid to the uniformity of the electric field, impurities, the shape and irregularity of the electrode, etc., and the dielectric strength of SF6 The intensity has a certain intensity. The moisture in SF6 gas will affect the insulation. When the water content in SF6 exceeds a certain concentration, SF6 may decompose at a temperature above 200°C. The decomposition product contains hydrofluoric acid, which is a highly corrosive and highly toxic acid. In addition, moisture condensation is also harmful to edge insulation. Therefore, in SF6 electrical equipment, the moisture content should be strictly controlled.
