K9AE31000
5
Schneider Eletric
Design guide
Short-circuit current withstand is shown in the table below.
This value must be greater than the prospective short-circuit current, at all points of
the installation.
Calculate the short-circuit current value at the worst case points.
Check the chosen rating allows the busbar trunking to cope with this short-circuit
current.
If this is not the case, there are 2 possible solutions:
choose a higher rating busbar trunking and re-check,
provide a peak current limiting protection system upstream of the busbar
trunking.
Standard version 3L + N + PE or 3L + PE
Unit
KTA08 KTA10 KTA12 KTA16 KTA20 KTA25 KTA32 KTA40
Allowable
rated short-
time withstand
current (t =1s)
Icw kArms / 1s 31
50
50
65
70
80
86
90
Allowable
rated peak
current
Ipk kÂ
64
110
110
143
154
176
189
198
Maximum
thermal stress
I
2
t A
2
s.10
6
961
2500
2500
4225
4900
6400 7396
8100
Reinforced version 3L + N+ PER
Allowable
rated short-
time withstand
current (t=1s)
Icw kArms / 1s 35
65
65
85
110
113
113
120
Allowable
rated peak
current
Ipk kÂ
73
143
143
187
242
248
248
264
Maximum
thermal stress
I
2
t A
2
s.10
6
1225
4225
4225
7225
12100 12769 12769 14400
Canalis KT is more than sized to cope with short-circuit currents.
Some specific cases require checks to be carried out: transformers in parallel, low
rating Canalis installed close to a transformer, etc.
b
b
b
b
b
To allow for extensions, the busbar trunking is generally protected at its nominal
current Inc (or its allowable current Iz if the ambient temperature coefficient k1 is
applied).
Circuit breaker protection:
adjust Ir of the circuit breaker such that:
Iz = Ib x k1 y Ir y Inc
Circuit breaker protection allows the Canalis busbar trunking to be used at full
capacity because the standardised nominal current In of the circuit breaker is
In y Inc / K2 where K2 = 1.
Protection using gG (gI) fuse:
determine the standardised nominal current In of the fuse such that: In y Inc / K2
where K2 = 1.1.
choose the standardised rating In that is equal to or just lower.
Check the following condition: In u Ib x k1 = Iz.
If this condition is not met, choose the busbar trunking with the next rating up.
Note: using gI fuses for protection means reducing the busbar trunking's allowable
current.
b
v
b
v
v
v
Design guide
Sizing the busbar trunking
Canalis KTA
8 - Checking the rating and choice of circuit breaker with respect to short-circuit withstand current
7 - Protecting against busbar trunking overloads.