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Design guide

Document source : www.engineering.schneider-electric.se

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K9AE31000
Ib
Ib
Ib
Ib
Ib
Ib
Ib
In
Ib
Ib
Ib
Ib
Ib
DD210066
3
Schneider Eletric
Design guide
Design guide
Determining the rating
Providing power distribution using
Canalis
Calculation of the total current (Ib) absorbed by a run is equal to the sum of the
currents absorbed by all of the loads.
The loads do not all operate at the same time and, as they are not continuously at
full load, a stacking or simultaneity factor Ks has to be taken into account:
Ib =
Ib load x Ks
Stacking factor Ks depending on the number of loads according to
IEC 60439- 1
Application
Ks coefficient
Lighting, heating
-
1
Distribution (mechanic
workshop)
2...3
0.9
4...5
0.8
6...9
0.7
10...40
0.6
40 and over
0.5
Caution: for industrial installations, remember to take into account future increases in the
number of machines. A 20 % reserve is recommended.
According to the WHO (World Health Organisation), exposure to radiated
electromagnetic fields above 0.2 micro Tesla can be dangerous causing a risk of
cancer over the long term. Some countries have standardised the limit: Sweden =
0.2 µT, at a distance of 1 metre.
All electrical conductors generate a magnetic field, the strength of which is
proportional to the distance between them. The Canalis busbar trunking concept
(metal casing and conductors near together) helps to considerably reduce radiated
electromagnetic fields.
In specific cases where particularly low values are required (computer rooms,
hospitals, some offices), it is important to keep in mind the following:
the induction generated around 3-phase distribution. This is proportional to the
current and the distance between the conductors, and inversely proportional to the
square of the distance with respect to the busbar trunking and the screening effect
of the case,
the induction generated around busbar trunking. This is less than the induction
generated around an equivalent cable distribution,
Canalis' steel casing. This attenuates the induction more than an equivalent
aluminium casing of the same thickness (screening effect),
the induction generated around busbar trunking with sandwiched bars. This is
particularly low because of the short distance between the bars and the additional
attenuation provided by the steel casing.
b
b
b
b
Ambient temperature
Canalis busbar trunking is sized to operate at an ambient air which does not
exceed + 40 °C and its average over a period of 24 h does not exceed + 35 °C.
Above this value, the busbar trunking must be derated.
Example: Canalis KT 1250 A installed inside with an ambient temperature of 45 °C:
In = 1250 x 0.93 = 1162 A.
In u Ib x k1 = Iz
Where k1 = ambient temperature derating coefficient.
Type of installation
Ambient temperature 24 hours average (°C)
35
40
45
50
55
Busbar trunking
installed inside
k1=1
k1=0,97 k1=0,93 k1=0,90 k1=0,86
Busbar trunking
installed outside under
an aluminium roof
Busbar trunking
installed in a fire duct
Canalis KTA
3 - Determining the current rating (Ib)
4 - Calculating nominal current (ln) by applying a derating coefficient
DD210982

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Summary :

K9AE31000 Ib Ib Ib Ib Ib Ib Ib In Ib Ib Ib Ib Ib DD210066 3 Schneider Eletric Design guide Design guide Determining the rating Providing power distribution using Canalis Calculation of the total current (Ib) absorbed by a run is equal to the sum of the currents absorbed by all of the loads. The loads do not all operate at the same time and, as they are not continuously at full load, a stacking or simultaneity factor Ks has to be taken into account: Ib = Ib load x Ks Stacking factor Ks depending on the number of loads according to IEC 60439- 1 Application Number of loads Ks coefficient Lighting, heating - 1 Distribution (mechanic workshop) 2...3 0.9 4...5 0.8 6...9 0.7 10...40 0.6 40 and over 0.5 Caution: for industrial installations, remember to take into account future increases in the number of machines.

Tags : trunking,busbar,canalis,distance,ambient,induction,casing,temperature,current,distribution,installed,generated,around
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