Selection of Copper Bar Bus for Low Voltage Switchgear

Selection of Bus Bus in Cabinet

In normal project design, several main circuits in low-voltage switchgear cabinet are connected to bus buses. The estimated maximum current passing through bus buses at any time is the sum of rated currents of all main circuits connected to it multiplied by rated dispersion coefficient (see Table 2). The specifications of bus buses are selected according to the expected maximum current. The specification selection of vertical bare copper busbar for feeder cabinet and the corresponding rated carrying capacity are shown in Table 3.

Table 2: Rated dispersion coefficient values (citing standard GB 7251.1-2005 4.7 Table 1)

Number of Main Circuits, Rated Dispersion Coefficient

2 and 3 0.9

4 and 5.0.8

6-9 (including 9) 0.7

Over 10. 0.6

Table 3: Vertical Bare Copper Bus Rated Flow Meter (Phase Spacing a = 80)

Bus Specification

(Width x Thickness) mm Rated Current (A)

IP30/IP40 IP5X

100 x 10 1800 1400

80 x 10 1500 1150

60 x 10 1250 900

40 x 10 850 630