Insulation support for low-voltage switchgear

For low-voltage switchgear, it consists of frame circuit breakers, molded case circuit breakers and their control, protection, indication systems, busbars, insulation components, cabinets, drawers and their connectors, functional units, etc. In addition to the electrical system composed of the core circuit breaker and its control unit, the busbar (copper bar) that conducts current, as well as the supporting busbar, are insulated from grounding components such as cabinets and metal mounting plates, and can withstand the huge electric force generated by the busbar in the event of a short circuit.

These two are the main functions of insulation components, as well as shielding, isolation, and other functions. Therefore, the insulation components supporting the busbar need to be insulated and have mechanical strength. Insulation includes clear distance and creepage distance. The clear distance ensures the straight-line air distance between the copper busbar and the installation plate, as well as between different phases. The creepage distance is also the shortest distance to "crawl" along the outer surface of the insulation relative to ground and between phases. There are mountain climbing, ditch climbing, and crawling along the "umbrella skirt" of the insulation outer surface.

There are many structural forms of busbar insulation, and the commonly used one is the insulation frame form. The upper and lower half clamps such as SMC and DMC are cast to fix the busbar in the middle, which is fixed in the middle by bolts. Building block modules are used to adapt to different specifications of copper bars, indicating that many materials are used.

Busbar clamp, tooth shaped (comb shaped) structure, made of DMC material, only fixes a part of the copper bar. Copper bars of different widths use the same busbar clamp, but the length of the fixing bolts is different.

Enhance nylon busbar clamps, such as B cabinet comb type busbar clamps, by sandwiching 5mm thick copper bars between upper and lower busbar clamps. The busbar clamps are fixed to the supporting aluminum alloy (or stainless steel) plate through buckles, and the upper and lower support plates are fixed with extended bolts. Nylon brackets use less material, have good insulation performance, high mechanical strength, and flexible installation. According to the calculation of electric power, it can be defined whether to fix both the upper and lower parts on a solid, or to fix one side on the cabinet and suspend the other side to ensure mutual fixation between phases. Comb type busbar clamps can be used for busbars with a maximum thickness of 5mm and a width of 200mm, indicating high strength of busbar clamps. Compared to thin plates, the skin effect coefficient of the 5 * 200 busbar is extremely low, the AC resistance is small, the circumference is large, the heat dissipation area is large, the temperature rise is low, and the current carrying capacity is large. The 5-5 * 200 copper busbar can carry a current of 6300A.

Other similar busbar clamp structures, reinforced with nylon material, high strength, and high production efficiency.

The busbar nylon support and insulation components are fixed on the mounting plate, and the copper bars are directly fixed with bolts, and insulated between the insulation components and the mounting plate.

Installation of insulators, using hexagonal insulators to fix the busbar. The insulators are made of BMC material die-casting, with a height of 50mm, a bending resistance of 8000N, high strength, and large creepage distance, suitable for ship switchgear.

Clamp form, for C-shaped and other irregular busbars, clamps are directly fixed on the cabinet partition, which is simple and convenient. The reinforced nylon material ensures insulation between the fixed installation plate and meets the requirement of a creepage distance greater than 16mm.

As mentioned earlier, the insulation components need to ensure that the copper bars can withstand short-circuit current and peak withstand current without causing damage to the insulation components. Therefore, high-strength insulation support can transmit more force to the mounting plate and withstand larger short-circuit currents. Failure of 85kA 1s vertical busbar, insulation cracking.