DC-bus operation Basic dimensioning Cable protection 7 7.5 7.5.7 7.5.7 Cable protection In case of interferences, the cables have to be adequately protected (7.4.4). Please consider the following when dimensioning the DC bus for a plant or machine: ƒ Mains fuses can be used to protect the DC cables if the wiring is designed for 122 % of the rated fuse current. Otherwise, the cable protection for the DC cables must be specially determined. ƒ Select the fuses for the currents resulting from power P DC100% . Please observe the standards and regulations applicable for the particular location and application. ƒ Fuse the DC-supply modules according to the Technical data on the AC mains side.
ƒ The DC outputs of the supply modules need not be fused if all connected controllers are fused in accordance with the specifications. ƒ ”Multi Drive” controllers are default equipped with a fuse in the installation backplane. The fuse is only effective if the DC busbar is used. In this case, a single pole fusing against short-circuit is sufficient. ƒ ”Single Drive” controllers can be retrofit with a fuse in the mounting backplane. The fuse will only be effective if the DC busbar is used. In this case, a single-pole fusing against short-circuit is sufficient. For retrofitting, use the E94AZJA0xx busbar mounting set.
ƒ If the DC bus is wired via the terminals +UG/-UG, always select a 2-pole cable protection. 7.5-5 EDS94SPP101 EN 3.1-04/2007