K9AE31000
4
Schneider Eletric
Design guide
Sizing the busbar trunking
The voltage drop between the start and all points of use must not be greater than
the values in the table below:
Installation supplied by:
Lighting
Other use
Low voltage public distribution network
3 %
5 %
High voltage distribution network
6 %
8 %
The allowable voltage drop is that which is compatible with correct load operation
(refer to manufacturers' guides).
Read voltage drop in V / 100 m / A for the busbar trunking chosen in accordance
with temperature rise.
Determine the voltage drop for the worst case loads, i.e. those furthest from the
source and for the highest current.
If the voltage drop exceeds allowable limits, choose the next rating up.
Re-check the voltage drop for the new rating.
Voltage drop, in volts per 100 metres and per amp for 3-phase 50 Hz current with
load spread over the run. For loads concentrated at the end of a run (transport),
the voltage drops are double those shown in the table below:
Delta U for evenly distributed loads (V / 100m / A)
KTA08 KTA10 KTA12 KTA16 KTA20 KTA25 KTA32 KTA40
Cosine = 1
0.0072 0.00493 0.00405 0.00303 0.00254 0.00219 0.00158 0.00127
Cosine = 0.9
0.0073 0.0050 0.00421 0.00322 0.0027 0.00227 0.0017 0.0014
Cosine = 0.8
0.0069 0.00478 0.00402 0.0031 0.0026 0.00217 0.00165 0.00138
Cosine = 0.7
0.0064 0.00444 0.00376 0.00292 0.00246 0.00203 0.00156 0.00132
Example: for the KTA1600 A busbar trunking:
Ib = 1530 A
In = 1600 A
Length L = 87 m
Cosine = 0.8.
According to the above table, the voltage drop coefficient for 100 metres and per
amp is equal to 0.0031V / 100m / A.
0.0031 x 0.87 x 1530 = 4.12 V
For a voltage = 400 V, in percentages:
4.12 / 400 = 0.0103 that is to say 1%.
b
b
Design guide
Nominal current In (A)
Busbar trunking
0 to 800
KTA0800
801 to 1000
KTA1000
1001 to 1250
KTA1250
1251 to 1600
KTA1600
1601 to 2000
KTA2000
2001 to 2500
KTA2500
2501 to 3200
KTA3200
3201 to 4000
KTA4000
Canalis KTA
6 - Checking the rating with respect to allowable voltage drop.
5 - Choosing the busbar trunking rating according to the nominal current ln