How to choose accessories for busbar trunking series

The major difference in accessories refers to the differential circuit composed of all branch currents except for the bus tie switch and section switch. The small difference of a certain section of busbar refers to the differential circuit composed of all the branches connected to the busbar, including the busbar and section switches, and the current. The large difference ratio differential of the busbar is used to distinguish between faults within and outside the busbar area, while the small difference ratio differential is used for the selection of fault busbars.

Usually, in the case of dual bus protection, the larger difference is used as the initiating component area, and the smaller difference is used as the selecting component area to distinguish which bus has the disadvantage. The difference between the large and small differential actions in the mother differential protection is that the small differential action,Open the busbar switch within the time limit, and then open all switches connected to the same busbar as the defective equipment. The big difference action is to trip all switches within the same time limit, regardless of which bus the equipment is attached to. Under normal dual mother operation, the input is small and selective. During the process of reversing the busbar, the busbar difference is set to a large difference to avoid the protection misoperation caused by the circulating current during the operation of the parallel knife switch in the busbar slot. The major difference is more of a starting component, and the key is to choose the faulty busbar based on the minor difference, and then take action. As for the protection plan, the major difference is non selective. The protection plan consists of two busbars, while the minor difference is selective, which can distinguish which busbar has a disadvantage. The protective action will trip all switches and bus tie switches on the defective busbar. So the editor suggests that when choosing, you should identify your needs.