The high-voltage load switch is a combined high-voltage apparatus, which is composed of disconnector, fuse, thermal relay, shunt release and arc extinguishing device.
High voltage load switch has a simple arc extinguishing device, which can only be used to make and break normal load current, but not to break short-circuit current. Therefore, the high-voltage load switch often cooperates with the high-voltage fuse and the thermal release. When the short-circuit is short-circuit, the short-circuit current is cut off by the fuse. When the load is overloaded, the thermal release acts to make the load switch trip automatically. Due to the obvious gap when the load switch is disconnected, it also has the function of isolating power supply and ensuring safe maintenance.
What are the functions of high voltage load switch
High voltage load switch and combined electrical apparatus are suitable for three-phase 10 kV, 50 Hz power system, or with complete sets of power distribution equipment, ring network switch cabinet, combined substation, etc. they are widely used in area network construction and transformation projects, industrial and mining enterprises, high-rise buildings and public facilities. They can be used as ring network power supply or terminal, playing the role of power distribution, control and protection. It has the advantages of large breaking capacity, safety and reliability, long electrical life, frequent operation, compact structure, small volume, light weight, and no maintenance. It has rated breaking current and overload current. It can break short-circuit current and prevent equipment from phase loss operation. The switch has obvious isolation fracture. Equipped with electric spring mechanism of grounding switch with closing ability, it can be remotely controlled.
Load switch (QL) is a kind of switch equipment which is used to make and break load current. The high-voltage load switch has simple arc extinguishing device and obvious breaking point, which can turn on and off load current and overload current, and also has the function of isolating switch, but it can't cut off short-circuit current. In most cases, load switch factory and fuse are used together to cut off the fault current with the help of fuse, which can be widely used in urban and rural power grid reconstruction. It is mainly used in 6 ~ 10kV power grid.
According to the arc extinguishing medium, high-voltage load switches are mainly divided into gas producing type, compressed air type, vacuum type and SF6 type, and indoor type and outdoor type according to installation location.
The load switch has the advantages of simple structure, small size and low price, which is suitable for oil-free, no maintenance and frequent operation. With fuse, it can be used as power switch for small or unimportant users to replace circuit breaker. Load switch is selected according to rated voltage and current, and verified by pressing and thermal stability. When the fuse is equipped, the breaking capacity of the fuse should be checked, and its dynamic and thermal stability can not be checked.