The common low-voltage distribution cabinet and high-voltage distribution cabinet are not simply referring to the distribution cabinet itself. They are actually what we commonly refer to as a complete set of equipment. In fact, this term is not accurate, and the scientific name should be "complete set of distribution equipment". So what is a complete power distribution device and what are its characteristics?

What is a complete power distribution device?

A switchgear (also known as a complete set of switches or distribution devices) is an electrical equipment mainly composed of circuit breakers; A complete set of power distribution equipment is a set of equipment supplied by the manufacturing plant. The manufacturing plant pre assembles the high and low voltage electrical equipment (including control appliances, protective appliances, measuring appliances, such as circuit breakers, isolating switches, transformers, etc.) of each circuit, as well as busbars, current carrying conductors, insulators, etc., in enclosed or semi enclosed metal cabinets according to the requirements of the main wiring, forming a unit circuit sub cabinet. This unit circuit sub cabinet becomes a complete set of power distribution equipment. During installation, according to the main wiring method, each unit is combined into individual cabinets (also known as intervals) to form the entire power distribution device.

The equipment composed of busbars, isolating switches (high voltage), knife switches (low voltage), circuit breakers (air switches), voltage transformers, current transformers, power transformers, AC contactors, protective relays (thermal relays), lightning arresters, etc. in the complete set of electrical equipment is called primary equipment. The circuit composed of them according to their principle relationship is called a primary circuit or a primary scheme diagram.

In order to ensure the safe, reliable, and stable operation of the primary system, it is necessary to monitor the operating status of the primary system at any time, and to be able to control the primary system at any time by equipping many other electrical components and equipment.

For example: measuring instruments (ammeters, voltmeters, power factor meters, power meters, frequency meters, etc.), control signal components (signal lights, buttons, universal transfer switches, etc.), relay protection devices, etc. The circuit composed of them according to their principle relationship is called a secondary circuit or a secondary scheme diagram.

The complete set of equipment is mainly divided into: 0.4kV, 0.69kV, 1.2kV low-voltage switchgear; 3.6kV, 7.2kV, 12kV, 24kV medium voltage switchgear (current development trend), 40.5kV high voltage switchgear, power box (cabinet), lighting box, control box (cabinet, table), protection screen, DC screen, etc.

High voltage switchgear: a general term for high-voltage switches mainly used for power generation, transmission, distribution, and energy conversion, as well as control, measurement, protection devices, electrical connections (busbars), enclosures, support components, etc.

The "five protections" in the protection requirements of switchgear:

Prevent accidental opening and closing of circuit breakers

Prevent live opening and closing isolation switches

Prevent live closing of grounding switch

Prevent grounding on/off circuit breakers

Prevent accidental entry into charged intervals.

Corresponding relationship between the position and phase sequence of the busbar:

Protection level: The degree of protection provided by the shell, partition, and other parts to prevent the human body from approaching live parts and touching moving parts, as well as to prevent external objects from entering internal equipment.