The low -voltage power distribution system is a power distribution and substation (usually the transmission voltage of the power grid is reduced to the power distribution voltage)、High -voltage electricity line (that is, voltage above 1 kV)、Power distribution transformer、Low -voltage distribution line (voltage below 1 kV) and the corresponding control protection equipment composition。

    Composition

   Low -voltage circuit breakers: Low -voltage circuit breakers, also known as automatic switch，It is a manual switch function，Can automatically lose pressure、under pressure、overload、and short -circuit protection electrical appliances。It can be used to allocate power，Start the asynchronous motor not frequently，Practice the power line and motor protection，When they have serious overload or short circuit and under pressure, they can automatically cut off the circuit，Its function is equivalent to a combination of fuse switch and over -thermal relay。And generally does not need to change the parts after dividing the fault current，I got a wide range of applications。

(1) Annexation of circuit breakers

   (2) Micro -broken circuit breaker: micro -circuit breaker，referred to as mcb，It is the most widely used terminal protection appliance in building electrical terminal power distribution devices。

   (3) Plastic shell circuit breaker: Plastic shell breaker can automatically cut off the current after the current exceeds the escape setting。Plastic shell refers to the shell of the device with a plastic insulator，Used to isolate the conductor and the ground metal part。Plastic shell circuit breaker usually contains arm magnetic jumping unit，and a large -scale plastic shell circuit breaker will be equipped with solid -state lumping sensor。

   (4) Frame -breaker

   (5) Smart universal circuit breaker

   Intelligent power distribution:

   (1) Low -voltage non -contribution compensation complete set device

   (2) Composite switch

   (3) Operating handle

   (4) No Revice Compensation Controller

   Low -voltage power distribution switch:

   (1) Load switch: Load switch,As the name suggests, it is a switch that can cut off the load current,To distinguish between high -pressure disconnects,Load switch has no arc extinguishing ability,Can't open the fault current,You can only turn off the load current under normal operation of the system,Load switch is named after this。

   (2) isolation switch: isolation switch is the most used electrical appliance in high -voltage switch electrical appliances，Its working principle and structure of it are relatively simple，But due to the large amount of use，High work reliability requirements，Payment of substation、Design of power plants、The impact of establishing and safe operation is greater。The main feature of the knife gate is the ability of no arc，It can only be divided when there is no load current、Circuit measures。

   Location, meaning

   1、i represents all the insulation part of the power part。T indicates that it is a neutral point directly ground。

   2、T means that the device shell is directly ground，It has no direct relationship with any other location in the system; n means that the load uses zero protection。

   3、C means that the working zero line and the protection line are unified; S means that the working zero line and the protection line are strictly separated。

    The secondary power distribution system is protected by relay、Safety automatic control、System communication、Schedule automation、DCS automatic control system and other systems。Secondary system is an indispensable part of the power system，It is a system of connection between people and a system、Control，Make a system run safely and economically。