How to choose standard parts for switch cabinet?

 Fasteners are an important part of the Switchgear. Aswitchgear needs to use many bolts, nuts, washers, rivets and other fastening standard parts. Although it seems insignificant, their selection and application directly affect the function, safety and economy of the switchgear. The function is to meet the structural design requirements, such as using countersunk bolts, square neck bolts, etc.

When choosing switch cabinet fasteners, we must first pay attention to functional availability, protection level, and aesthetics and economy. Functional availability depends on meeting the structural design requirements. Fasteners with different protection levels will also be different. For example, medium-voltage switch cabinets generally require IP4X, which means that objects larger than or equal to one millimeter are not allowed to enter. Places where long waist holes are used for installation require enlarged gaskets to completely cover the holes. As for aesthetics and economy, we must choose economical and affordable fasteners while meeting the requirements of functionality and safety.

When the switch cabinet is used in parallel, there are different requirements for fasteners. The switch cabinet needs to be arranged and connected in parallel. There should be no gaps between the switch cabinets. After the cabinets are assembled, the fasteners should not collide and interfere with each other, which will increase the gap and affect the parallel connection. There are generally two methods. One is to use an inward boss with a boss depth of 2mm, 5mm, etc., depending on the application of the fasteners of the installation components. The switch cabinet body is spliced ​​with M6 square neck bolts, mainly to facilitate disassembly and replacement in case the switch cabinet is misassembled or designed incorrectly.

The side panels of the switch cabinet are double-folded outward, so there is a 2mm gap in the middle part. For self-tapping screws, this space can be used to ensure that there are enough teeth, and it can also ensure that some thicker screw heads can be installed.

For the front and rear connections, countersunk bolts are used at the front and rear connections, and the bolt head position needs to be avoided from the door panels, cover plates, etc. The cover plate bolts need to meet the IP and internal arc fault requirements, and the convenience of installation must also be considered. Generally, M8/, M10 hexagon socket bolts are used, and a special hexagon socket wrench is used to meet the requirements of tool-based cover opening.

For busbar connection, for low-voltage busbars with low voltage of 12kV and below, the busbars use 8.8-grade M10/M12 hexagonal head bolts + flat washers + spring washers (or pressure washers) + hexagonal nuts to ensure that the torque meets the specification requirements. For high-voltage busbars with primary conductive circuits such as 24kV and above high-voltage busbars, high-strength hexagonal flat round head bolts are required, and the nuts also need to use round head cap nuts to avoid electric field concentration and ensure that the switchgear can withstand overvoltage damage. High-current busbars can use A4-80 grade stainless steel bolts with A4 grade nuts to reduce the impact of eddy currents and reduce temperature rise.

The application of the above fasteners will affect the function, safety and economy of the switch cabinet. Through reasonable selection, the assembly efficiency and operation stability of the switch cabinet can be effectively improved.