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D-23
Designing horizontal busbars
Additional informations
Permissible current and selection of horizontal busbars
The goal is to optimise busbar size according to the installation and operating criteria.
Up to 1600 A
Flat busbars, 5 mm thick
Type of bars
Permissible current (A)
Ambient temperature around the switchboard
25 °C
30 °C
35 °C
40 °C
45 °C
50 °C
Size per phase
IP
y
31 IP > 31 IP
y
31 IP > 31 IP
y
31 IP > 31 IP
y
31 IP > 31 IP
y
31 IP > 31 IP
y
31 IP > 31
1 bar, 60 x 5 mm
890
840
850
790
800
750
760
700
710
650
660
b
1 bar, 80 x 5 mm
1130 1050 1080 990
1000 900
970
870
910
810
860
b
2 bars, 60 x 5 mm
1580 1420 1500 1350 1400 1250 1350 1180 1260 1090 1180
b
2 bars, 80 x 5 mm
2010 1820 1920 1720 1800 1600 1720 1510 1610 1390 1510
b
Up to 3200 A
Flat busbars, 10 mm thick
Type of bars
Permissible current (A)
Ambient temperature around the switchboard
25 °C
30 °C
35 °C
40 °C
45 °C
50 °C
Size per phase
IP
y
31 IP > 31 IP
y
31 IP > 31 IP
y
31 IP > 31 IP
y
31 IP > 31 IP
y
31 IP > 31 IP
y
31 IP > 31
1 bar, 50 x 10 mm
1330 1220 1260 1160 1200 1080 1130 1010 1060 940
990
b
1 bar, 60 x 10 mm
1550 1400 1470 1320 1400 1250 1320 1160 1240 1070 1160
b
1 bar, 80 x 10 mm
1990 1800 1890 1700 1800 1600 1700 1500 1600 1390 1500
b
2 bars, 50 x 10 mm
2270 2090 2160 1980 2050 1850 1930 1740 1810 1610 1690
b
2 bars, 60 x 10 mm
2550 2270 2420 2140 2300 2000 2170 1870 2030 1720 1900
b
2 bars, 80 x 10 mm
3110 2820 2970 2660 2820 2500 2660 2330 2500 2160 2330
b
2 bars, 100 x 10 mm
3650 3280 3490 3100 3300 2900 3130 2720 2950 2510 2750
connection impossible due to the operating-temperature limits of the devices
installed in the switchboard.
Example
Two 50 x 10 mm bars can be used for a 2160 A current with an IP
y
31 and an
ambient temperature of 30 °C around the switchboard.
Where possible, use of 10 mm bars is worthwhile in terms of the In/Isc:
gain in time during switchboard mounting given, where applicable, the lesser
number of bars installed
for short-circuits, the rigidity of the bars means fewer busbar supports.
Recommendation
Use 5 mm bars for In
y
1600 A and low Icw values (40 kA rms).
Use 10 mm bars for In > 1600 A and medium to high Icw values (> 40 kA rms).
Note:
the values indicated above have been validated for Prisma Plus switchboards.
b
b
b
Designing electrical
characteristics