Busbar Support

The busbar supports are used to create a 3 or 4-pole busbar system with conductor heights from 30 – 100 mm. The bar can have both individual conductors and double conductors per phase. Different phase center spacings permit adaptation of the busbar system to different room dimensions or concepts with different short-circuit strengths. The nominal operating voltage according to IEC 61439 is 1000VAC or 1500VDC.

When it comes to short-circuit current, a distinction is made between surge current and continuous short-circuit current. It is the continuous short-circuit current that is responsible for heating the conductor. It is proportional to the current square I² and the duration of the short circuit t.

The surge current generates the maximum force that is exercised on the current-carrying conductors and therefore on the supports. The spacing between two neighboring supports can be changed to absorb the forces of the maximum expected surge current. This dependence for supports SH1 and SH3 is shown in the diagram. With a given current, this permits calculation of the maximum admissible spacing between the busbar supports for different bar formats. The maximum spacing differs between busbar supports.

Surge current

With a Cu bar measuring 30x10 mm and a support spacing of 250 mm, the maximum short-circuit current is 110 kA

The busbar supports are made of glass fiber-reinforced polyamide 6.6 and are self-extinguishing in line with UL 94 V0. The material permits a maximum bar temperature of 120°C and is halogen free. The top and bottom sections of a support are identical, thereby ruling out the problem of interchanging. The two support sections are connected to each other via threaded rods or threaded bolts. The spacing of the support sections is defined by so-called spacers to suit the bar height.

5 supports are required for laying within a switch cabinet. This is why the busbar supports are available in packs of 10, equivalent to 5 supports.

The length of the required threaded rods depends on the bar height plus the length for securing of the support on the base structure.