Calculating Network Power Supply Unit Installation Position And Current Capacity - Mitsubishi Electric A1SJ71DN91 User Manual

5. SETTINGS AND PROCEDURES BEFORE OPERATION
5.6.2

Calculating network power supply unit installation position and current capacity

Network
power supply
unit
Termination
resistance
Termination
resistance
Master
0.1A
This section describes the calculating network power supply unit installation position and
current capacity.
(1) Network power supply unit connected to an end of the network
The current capacity is calculated as shown below when the network power supply unit is
connected to the end of a thick-cable network with a total length of 200 m.
Master station master Slave station
0.1A 0.15A
Total power supply distance = 200 m
Total current capacity = 0.1 A + 0.15 A + 0.05 A + 0.25 A + 0.1 A = 0.65 A
Max. current capacity of 200 m of thick cable (from Table 5.1) = 1.53 A
Therefore, this configuration allows power supply to all stations.
(2) Network power supply unit connected to the center of the network
The current capacity is calculated as shown below when the network power supply unit is
connected at the center of a thick-cable network.
In this case, the network power supply unit can supply twice the current compared to
when it is connected to the end of the network.
Slave station Slave station
0.25A 0.2A
120m
Power supply distance left of the network power supply unit = power supply distance right
of the network power supply unit = 120 m
Total current capacity to the left = 0.1 A + 0.25 A + 0.2 A = 0.55 A
Total current capacity to the right = 0.15 A + 0.25 A + 0.15 A = 0.55 A
Max. current capacity of 120 m of thick cable (from Table 5.1) = approx. 2.56 A
(Linearly interpolated between 100 m and 150 m.)
Therefore, this configuration allows power supply to all stations.
Slave station Slave station
0.05A 0.25A
200m
Network
power supply
unit
Slave station
0.15A
120m
−
5 8
MELSEC-A
Slave station
0.1A
Slave station Slave station
0.25A 0.15A
Termination
resistance
Termination
resistance