What are the main types of low voltage switchgear

by changan electric

Low voltage switchgear from the structure of the way divided

(1) Fixed type

Can meet the electrical components reliably fixed in the cabinet to determine the position. Cabinet shape is generally cubic, such as screen type, box type, etc., but also prismatic body such as desktop. This cabinet has a single column, there are also arrangements.

In order to ensure that the cabinet shape size, often take the components step-by-step combination of the way, generally composed of two pieces or left and right sides, and then composed of the cabinet, or first to meet the shape requirements, and then connected in turn to the cabinet internal branch. Composition of the cabinet body of each edge of the length of the parts must be correct (tolerance to take negative values), in order to ensure that all aspects of geometric size, so as to ensure that the overall shape requirements. For both sides of the cabinet surface, because of the need to consider the arrangement, the middle can not have the phenomenon of bulge.

In addition, from the installation point of view, the bottom surface can not have the phenomenon of sinking. In the arrangement of installation, the foundation is flat prerequisite, but the dry whole degree and the cabinet itself have a certain error, in the arrangement to try to offset the lateral difference, and do not cause the accumulation of the difference, because the accumulation of the difference will cause the cabinet deformation, affecting the busbar linkage and produce components installation isochronism, stress concentration, and even affect the life of the appliance. Therefore, it is appropriate to use the highest point of the foundation for the installation of the reference point, and then gradually pad positive expansion row, in the bottom of the dry degree of ideal and predictable conditions, can also be taken from the middle to both sides of the expansion of the row, so that the accumulated differences are evenly distributed.

In order to easy to adjust, offset tolerance accumulation, cabinet width tolerance are taken negative values. Cabinet of each component combined with the body is completed, as needed should also be shaped to meet the requirements of each part of the shape and size. For stereotypes or batch of larger cabinet manufacturing should be fully considered with tooling fixtures to ensure the correct structure of unity, fixture benchmark surface to take the bottom surface as appropriate, the fixture in the positioning block arrangement to work to remove the convenience of the prevailing, for the outer door of the cabinet, etc. because of easy transport and installation, etc., generally in the installation of unified adjustment.




(2) pull-out type

Pull-out type is fixed by the cabinet body and equipped with switches and other major electrical components of the removable device part, removable part of the shift to light, move into the positioning to be reliable, and the same type and specifications of the drawer can be reliably interchangeable, pull-out type in the cabinet body part of the processing method is basically similar to the fixed type in the cabinet body. But because of the interchangeable requirements, the precision of the cabinet body must be improved, the relevant part of the structure should have enough adjustment amount, as for the removable device part, to be able to both move and change, but also to reliably load the main components, so there should be high mechanical strength and high precision, and its relevant part should also have enough adjustment amount.

The process characteristics of manufacturing drawer-type low-voltage cabinet are

(1) fixed and removable parts should have a unified reference base.

(2) The relevant parts must be adjusted to the best position, and the adjustment should be made with special standard tooling, including standard cabinet and standard drawer.

(3) The error of key dimensions must not exceed the difference.

(4) The interchangeability of drawers of the same type and specification should be reliable .



Low voltage switchgear from the connection method

(1) welding type

Its advantages are easy processing, solid and reliable; disadvantages are large errors, easy deformation, difficult to adjust, less beautiful, and the workpiece generally can not be pre-plated. In addition, the welding clamps have certain requirements.

① good rigidity and will not be affected by the deformation of the workpiece.

② slightly larger than the nominal size of the workpiece, which can offset the impact of post-welding shrinkage.

③ flat, simple, easy to operate, minimize the rotatable mechanism to avoid jamming.

④ To prevent welding corrosion and easy maintenance and adjustment, to choose a good workpiece support, support but also add anti-welding corrosion pad.
Deformation of the workpiece after welding phenomenon is caused by the stress caused by the expansion of molecules at the weld due to the heat, extrusion produces microscopic displacement, and can not be reset after cooling. In order to overcome the impact of deformation, must consider the shaping process. The methods of shaping are generally.

① predict the range of deformation of the workpiece through tests, before welding to force the workpiece to deform in the opposite direction, with a view to reaching the predetermined size after welding.

② correction after welding with over-positive methods.

③ hit, pressure welding after the relative shrinkage part, and get the stress balance.



④ heating the relatively loose convex part after welding to achieve the same shrinkage as the weld.

⑤ If necessary, the overall heat treatment of the component.

In addition, the selection of welding points, welding seam towards, welding order, spot welding positioning on the phenomenon of post-welding deformation have a certain impact, such as properly handled to reduce deformation, but this depends on the specific circumstances.

(2) fastener connection

Its advantages are suitable for workpiece pre-plating, easy to change the adjustment, easy to beautify the processing, parts can be standardized design, and can be pre-produced inventory, frame shape size error is small. The disadvantage is that it is not as strong as welding, requiring high precision of parts, processing costs are relatively high. Fasteners are generally standard parts, the main types of conventional screws, nuts and rivets, pull rivets, as well as pre-tightened and fine-tunable clamp nuts and pre-tightened pull nuts, and self-tapping screws. There are also special fastening screws (such as the introduction of foreign low-voltage cabinets mostly with special fastening screws).

Process characteristics: to fixture shaping, tooling positioning, and as needed with pressure washers; riveting generally with drilling, and pre-plating parts to prevent damage to the coating; for precision machining center or special equipment processing components, such as the diameter of the connection aperture and fastener diameter can maintain a trace of clearance, it can be assembled without fixture, a forming; guide and positioning parts of the fastening, should be a special gauge first positioning and then to Standard tooling testing.

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