The basic functions of LV switchgear
Aug 20, 2020
The switchgear is a kind of electrical equipment. The outer line of the switch cabinet first enters the main control switch in the cabinet, and then enters the sub-control switch, and each branch is set according to its needs. According to different voltage levels, it can be divided into high voltage switch cabinet, medium voltage switch cabinet and low voltage switch cabinet. The low-voltage switchgear is suitable for power plants, petroleum, chemical, metallurgy, textiles, high-rise buildings and other industries for power transmission, distribution and power conversion.
1. Classification of low-voltage switchgear
Structure
(1) Fixed
It can be satisfied that the electrical components are reliably fixed in the determined position in the cabinet. The shape of the cabinet is generally cubic, such as screen type, box type, etc., and there are also prisms such as desktop. This kind of cabinet has a single row and also has an arrangement.
(2) Withdrawal type
The draw-out type is composed of a fixed cabinet and a movable device part equipped with main electrical components such as switches. The movable part should be light and portable when it is moved, and the positioning should be reliable after being moved, and the drawers of the same type and specification can be reliably interchanged and drawn out The processing method of the cabinet in the formula is basically similar to that in the fixed cabinet. However, due to the interchange requirements, the accuracy of the cabinet must be improved, and the relevant parts of the structure must have sufficient adjustments. As for the movable device part, it must be able to be replaced, and the main components must be reliably installed, so it must be higher. With high mechanical strength and high precision, the relevant parts must have sufficient adjustment.
The technological characteristics of manufacturing drawer type low voltage cabinet are:
(1) The fixed and movable parts must have a unified reference;
(2) The relevant parts must be adjusted to the best position, and special standard tooling should be used when adjusting, including standard cabinets and standard drawers
(3) The error of key dimensions cannot be out of tolerance;
(4) The interchangeability of drawers of the same type and specification should be reliable
From the connection method
Welded
Its advantages are convenient processing, sturdiness and reliability; its disadvantages are large errors, easy deformation, difficult adjustment, and poor aesthetics, and the workpieces generally cannot be pre-plated. In addition, there are certain requirements for welding clamps
(2) Fastener connection
Its advantages are that it is suitable for workpiece pre-plating, easy to change and adjust, easy to beautify, parts can be standardized design, and can be pre-production inventory, and the frame size error is small. The disadvantage is that it is not as strong as welding, requires high precision of parts and components, and the processing cost is relatively increased. Fasteners are generally standard parts, and their types mainly include conventional screws, nuts and rivets, pull rivets, pre-tightened and fine-adjustable clamp nuts and pre-tightened tension nuts, and self-tapping screws. There are also special fastening screws (for example, most low-voltage cabinets imported from abroad use special fastening screws).
Performance characteristics of low-voltage switchgear
1. Reasonable design: unitized design according to the characteristics of various switch electrics such as graphic production, and combined into functional units
2. The structure is universal and the assembly is flexible: C-shaped profiles meet the requirements of various structural forms. The requirements of the maintenance level and the surrounding conditions of use
3. Standard modules can be separately composed of standard unit module structures such as protection, operation, conversion, and control.
4. Safety protection: The isolation between areas and the mutual isolation of the incoming and outgoing lines of functional units are used to effectively strengthen the safety and protection performance.
5. Technical parameters: The main technical parameters are at the international leading level.
