Checking the power supply voltage
(Original Document)
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Introduction
The wiring check must ensure that the voltage of the module furthest away from the power supply source is not less than 19.2 V.
The consumption of the installation is due to the electricity supply to the modules and sensors.
Calculating the line loss
Line loss is calculated using the following values:
The following table outlines the calculation of line loss.
Length (m)
10
20
30
50
75
100
125
150
200
250
300
Number of modules
5
0.09
0.18
0.28
0.46
0.70
0.90
1.20
1.40
1.90
2.30
2.80
10
0.17
0.34
0.51
0.86
1.30
1.70
2.10
2.60
3.40
4.30
5.10
15
0.25
0.50
0.75
1.25
1.90
2.50
3.10
3.70
5.00
6.20
7.50
20
0.32
0.65
0.98
1.63
2.50
3.30
4.00
4.90
6.50
8.20
9.80
25
0.40
0.80
1.20
2.00
3.00
4.00
5.00
6.00
8.10
10.00
12.00
30
0.48
0.96
1.45
2.40
3.60
4.80
6.00
7.20
9.60
12.00
14.50
Examples
First example using the table.
24 VDC supplies power at +/- 3 %, the length of the bus is 100 m and 15 IP67 sealed I/O modules are used.
The voltage available in the last module shall be:
24 V - 3 % - (100 m and 15 modules = 2.5 V) = 20.78 V
Since the available voltage is greater than 19.2 V, a single power supply connected to the start of the bus can be used.
Second example using the table.
24 VDC supplies power at +/-5 %, the length of the bus is 100 m and 30 IP67 sealed I/O modules are used.
The voltage available at the last module shall be:
24 V - 5 % - (100 m and 30 modules = 4.8 V) = 18 V
Since the available voltage is less than 19.2  V, a second power supply must be inserted after 75 m using a TSX EF ACC 99 connection box.
Using 3-wire sensors
The connection of 3-wire sensors increases energy consumption. Using the table given above, the line loss will be multiplied by a coefficient of 1.77.
Third example using the table.
24 VDC supplies power at +/-5 %, the length of the bus is 50 m and 15 IP67 sealed I/O modules are used.
The voltage available in the last module shall be:
24 V - 5 % - (50 m and 15 modules = 1.25 V * 1.77) = 20.58 V
Since the available voltage is greater than 19.2 V, a single power supply connected to the start of the bus can be used.