Insulation of bus
In switchgear and control equipment, in order to achieve full insulation and full working conditions of the equipment, reduce external short-circuit accidents and prevent electric shocks and prevent creepage caused by condensation and pollution. Insulating materials are generally used outside the busbar to cover the exposed part of the busbar. Bound. The main methods are insulated thermal shrinkable tube (or air shrinkable tube) and busbar vulcanization. The low-voltage busbar is mainly composed of insulated PVC tube.
Bus support and fixation
(1) The support of the busbar must fully consider whether its bending strength meets the force effect requirements of the configured system.
(2) The bus bar is generally fixed with metal fittings, and bolts are not used to directly punch holes in the bus bar.
(3) When the insulator used to fix the busbar is subjected to large electric power (such as when the system rated peak withstand current is more than 40kA), it is necessary to verify whether the flexural strength of the insulator meets the requirements of structural design.
The verification of the force effect of the insulator can be as follows:
In the formula: Fjs-stress acting on the insulator, kg;
Fph—Bending strength of insulators, relevant samples can be checked;
L-span between insulators (support distance between busbars) (cm);
A—the distance between each other (cm);
Ich—rated peak withstand current (KA)
(4) Busbar clamps and fixed fittings should also be able to withstand the forces caused by the rated peak withstand current.
(5) The fixed fittings or other supporting fittings of the bus bar should not form a closed magnetic circuit.
(6) When the bus bar is horizontal, the upper pressure plate of the bus bar support plate should maintain a gap of 1-1.5 mm with the bus bar, and when the bus bar is standing, the upper pressure plate should maintain a gap of 1.5-2 mm with the bus bar.
(7) Between multiple rectangular bus bars, a gap of not less than the thickness of the bus bar should be maintained.
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(8) The metal plywood (except fasteners) at the end of the wall bushing of the busbar of 600A and above should use non-magnetic materials, and there should be metal connection between the busbar and the contact should be firm, and the thickness of the metal plywood should not be less than 3mm When the bus bar is two or more, the bus bar itself should be fixed.
(9) The fixation between the busbar fittings and the post insulator should be flat and firm, and the busbars supported by it should not be subjected to additional stress.