The low-voltage distribution system consists of distribution substation (usually reducing the transmission voltage of the power grid to the distribution voltage), high-voltage distribution line (i.e. voltage above 1kV), distribution transformer, low-voltage distribution line (voltage below 1KV) and corresponding control and protection equipment.
system composition
Low voltage circuit breaker
Low voltage circuit breaker, also known as automatic switch, is an electrical appliance that not only has the function of manual switch, but also can automatically protect against voltage loss, undervoltage, overload and short circuit. It can be used to distribute electric energy, start asynchronous motors infrequently, protect power lines and motors, and automatically cut off the circuit when they have serious overload, short circuit, undervoltage and other faults. Its function is equivalent to the combination of fuse switch and over and under heating relay. Moreover, after breaking the fault current, there is generally no need to change the parts, which has been widely used.
(1) Circuit breaker accessories. (2) Miniature circuit breaker: miniature circuit breaker, referred to as MCB, is the most widely used terminal protection appliance in building electrical terminal distribution devices. (3) Molded case circuit breaker: the molded case circuit breaker can automatically cut off the current after the current exceeds the trip setting. Plastic shell refers to the use of plastic insulator as the shell of the device, which is used to isolate between conductors and grounded metal parts. Molded case circuit breakers usually contain thermal magnetic trip units, while large models of molded case circuit breakers will be equipped with Solid-state trip sensors.
(4) Frame circuit breaker. (5) Intelligent universal circuit breaker.
Intelligent power distribution
(1) Low voltage reactive power compensation package; (2) Composite switch; (3) Operating handle; (4) Reactive power compensation controller;
Low voltage distribution switch
(1) Load switch: load switch, as the name suggests, is a switch that can cut off the load current. It should be different from high-voltage circuit breaker. The load switch has no arc extinguishing ability and can not cut off the fault current. It can only cut off the load current under the normal operation of the system. Therefore, the load switch is named. (2) Disconnector: disconnector is one of the most used high-voltage switchgear. Its working principle and structure are relatively simple. However, due to its large amount of use and high requirements for working reliability, it has a great impact on the design, establishment and safe operation of substation and power plant. The main feature of the knife switch is that it has no arc extinguishing capacity, and can only be opened and closed under the condition of no load current.
