1) The load switch that uses SF6 gas as insulation and arc extinguishing medium is called SF6 load switch. It can be used for making and breaking load current, as well as making and breaking no-load lines, no-load transformers and capacitor banks.
2) SF6 load switch can close short-circuit current, but cannot break short-circuit current.
3) SF6 load switch is generally three-position (closing, opening and grounding), and there is a mechanical interlock between the load switch and the grounding switch. There is also an interlock between the earthing switch and the cable compartment door. To ensure the safety of maintenance.
4) SF6 load switch has simple structure, convenient operation, low price, reliable action, less maintenance or maintenance-free, and some imported products can be maintenance-free for 30 years.
5) SF6 load switch has a low cut-off value to avoid high cut-off overvoltage. At the same current density, the arc diameter in SF6 is much smaller than that in air. When the current decreases, the diameter of the arc column also decreases, and the arc core can still maintain a relatively high degree of ionization to maintain the current flow until the current naturally crosses zero. After the arc column is narrowed, the fracture phenomenon generally does not occur, so it seldom causes the interception of overvoltage.
6) SF6 load switch + fuse combination electrical appliances are made by SF6 load switch to undertake the closing and breaking of the normal working current and overload current of the transformer, and also undertake the breaking of the transfer current. The fuse bears the protection of overcurrent and short-circuit current more than 3 times the rated value.
7) The load switch is linked with the striker of the fuse. The fuse is blown to open the pole current, the striker is knocked out, and the three-phase load switch is automatically opened at the same time through the linkage mechanism, which avoids the fuse and the transformer from being subjected to transfer current or fault current and transformer phase loss for a long time.
8) The performance of protecting the distribution transformer is good. When the oil-immersed transformer is short-circuited, in order to prevent the oil tank from exploding, the fault must be removed within 20ms. The current-limiting fuse has a quick-break function, coupled with its current-limiting function, it can remove the fault within 10ms and limit the short-circuit current value, which can effectively protect the transformer.
Post time: Jun-17-2022