Low voltage switchgear is an important equipment in power system, which is used to control, protect and distribute electric energy. Among them, busbar, equipment and unit are the key components of low-voltage switchgear. This article will organize and introduce these three knowledge points to help readers better understand the structure and function of low-voltage switchgear.

1. Busbar

busbar is the main conductive component in low voltage switchgear, which is used to transmit electric energy and connect various electrical equipment. Busbars are generally divided into three types:

• busbar: used to introduce the power supply into the low-voltage switch cabinet and connect the main transformer and switch equipment;
• horizontal bus: connecting different units or equipment to transfer electric energy;
• vertical bus: Connect equipment or units at different levels to realize the up and down transmission of electric energy.

Bus selection should consider the current load, temperature rise and voltage drop and other factors to ensure that the bus has sufficient conductivity and safety performance.

2. Equipment

the equipment in the low-voltage switch cabinet includes circuit breakers, contactors, fuses, etc., which are used to control the on-off of electric energy and protect the safety of the circuit. Common equipment is:

• circuit breaker: used for opening and closing circuit and overload protection, with short circuit protection function;
• contactor: used to control the start, stop and forward and reverse of the motor, with remote control function;
• fuse: used for overload and short circuit protection, through the fuse fuse characteristics to achieve protection.

The selection of equipment should be based on the circuit load, working environment and safety requirements and other factors to ensure the normal operation and safety of the circuit.

3. Unit

low-voltage switchgear usually divided into different units, each unit contains a set of equipment and control elements, used to achieve a specific function. Common units include:

• power supply unit: including power input, main circuit breaker and power monitoring device, used to provide power and monitor power conditions;
• control unit: including controller, contactor, button, etc., used to control and adjust the circuit;
• protection unit: including fuse, overload protector, etc., used to protect circuit safety.

Each unit is connected by busbars and connecting wires to form a complete low-voltage switchgear system.

4. Equipment interconnection and operation principle

the busbars, equipment and units in the low-voltage switchgear are interconnected through connecting wires and control signals to realize the transmission, control and protection of electric energy. In the process of operation, the bus introduces the electric energy into the switch cabinet, the on-off and protection of the equipment control circuit, and the unit realizes the coordination and cooperation of various functions, so as to ensure the normal operation of the circuit.