
105
6
Short-circuit current calculation
6-1 Calculating short-circuit current
Table 6-3 Cable impedance examples (600V vinyl cable)
Cable gauge
Reactance per meter of cable (
:
)
Resistance per meter of cable (
:
)
Insulated wire or cable inside
a steel tube or duct
Copper tube cable or vinyl
tube cable with no duct
Indoor cable with insulator
ø1.6mm
0.00020
0.00012
0.00031
0.0089
ø2mm
0.0056
ø3.2mm
0.0022
5.5mm
2
0.0033
8mm
2
0.0023
14mm
2
0.00015
0.00010
0.00026
0.0013
22mm
2
0.00082
30mm
2
0.00062
38mm
2
0.00048
50mm
2
0.00013
0.00009
0.00022
0.00037
60mm
2
0.00030
80mm
2
0.00023
100mm
2
0.00018
125mm
2
0.00014
150mm
2
0.00012
200mm
2
0.00009
250mm
2
0.00007
325mm
2
0.00005
.OTES s!DDREACTANCEONTHEPOWERSUPPLYSIDETOlNDTHEVALUEBECAUSE
reactance is 1.2 times higher at 60Hz.
s5SEORTHEACTUALCABLELENGTHTOCALCULATEREACTANCEAND
resistance when using two or three cables connected in parallel.
Table 6-4 Bus bar and bus duct impedance examples (50Hz)
Data: Furukawa Electric Co., Ltd.
Material
Rated current
(A)
Regular bus duct
Conductor dimensions
(mm)
Resistance
(
:
/m)
Reactance X
(
:
/m)
Impedance Z
(
:
/m)
Aluminum
(Al)
200
6
u
25
1.93
u
10
-4
1.25
u
10
-4
2.3
u
10
-4
400
6
u
50
0.97
u
10
-4
0.909
u
10
-4
1.33
u
10
-4
600
6
u
75
0.657
u
10
-4
0.72
u
10
-4
0.974
u
10
-4
800
6
u
125
0.404
u
10
-4
0.516
u
10
-4
0.655
u
10
-4
1000
6
u
150
0.343
u
10
-4
0.45
u
10
-4
0.566
u
10
-4
1200
6
u
100
u
2
0.249
u
10
-4
0.882
u
10
-4
0.916
u
10
-4
1500
6
u
125
u
2
0.201
u
10
-4
0.790
u
10
-4
0.815
u
10
-4
2000
6
u
200
u
2
0.133
u
10
-4
0.588
u
10
-4
0.603
u
10
-4
Copper
(Cu)
200
3
u
25
2.41
u
10
-4
1.312
u
10
-4
2.74
u
10
-4
400
6
u
40
0.751
u
10
-4
1.02
u
10
-4
1.267
u
10
-4
600
6
u
50
0.607
u
10
-4
0.91
u
10
-4
1.094
u
10
-4
800
6
u
75
0.412
u
10
-4
0.72
u
10
-4
0.830
u
10
-4
1000
6
u
100
0.315
u
10
-4
0.60
u
10
-4
0.678
u
10
-4
1200
6
u
125
0.261
u
10
-4
0.511
u
10
-4
0.573
u
10
-4
1500
6
u
150
0.221
u
10
-4
0.449
u
10
-4
0.500
u
10
-4
2000
6
u
125
u
2
0.129
u
10
-4
0.79
u
10
-4
0.800
u
10
-4