Page 925 - Industrial Power Engineering and Applications Handbook

Carrying power through metal-enclosed bus systems 28/875
effect as on a d.c. system then the reduction in the current The skin effect can be minimized by employing different
rating due to the skin effect can be deduced by equating configurations and arrangement of busbars, as discussed
the two heats, i.e. later and illustrated in Figure 28.14. It can also be
minimized by selecting hollow round or hollow rectangular
(channels in box form) conductors, and thus concentrating
the maximum current in the annulus and optimizing metal
(28.5) utilization. For current ratings in round and channel
sections, refer to Tables 30.8 and 30.9, respectively.

-=4 8 16 240
1.5
1.425 -

1.4

1.275 -
1 1.3-
5
cr"
.? 1.2
-
5 1.182
s= 1.13-
%..
-E 1.1
$
1055-

6.45 -
~ 1.0
10
-. 12.9 4
219.35,
c+ 20
... 02
"0 25.8-
$2 30
(j i3 38.71 -
@
1 50
40
@ lndal D 50 SWP at 85°C
60
@ lndal ClSM at 85°C
@ lndal D 50 SWP at 20°C
@ lndal ClSM at 20°C
@ lndal D 50 SWP at 85°C @ Copper at 85°C
@ lndal ClSM at 85°C @ Copper at 20%
@ lndal D 50 SWP at 20°C
@ lndal ClSM at 20°C
Note
Note
The lower cross sectional area curves relate to f= 50 Hz. For other The lower curves apply for f = 50 Hz only. For other frequencies,
must be calculated by multiplying these values by ,I%%
frequencies must be calculated by multiplying these values
by ,I%% (b) Channels in box form
(a) Flat bus bars
Figure 28.13(a) Skin effect in isolated rectangular busbars. (neglecting the proximity effect) (Courtesy: I?ndian Aluminium Co.
based Alcon of Canada)