5. SETTINGS AND PROCEDURES BEFORE OPERATION
5
−
10
MELSEC-A
(4) Mixed Trunk Line and Drop Line
The current capacity is calculated as shown below when the network power supply unit is
connected to a network with 200 m of thick-cable trunk line and
6 m of thin-cable drop line.
Thick-cable power supply distance = 200 m
Drop line power supply distance = 6 m
Total current capacity = 0.5 A + 0.15 A + 0.05 A + 0.25 A + 0.1 A = 1.05 A
Max. current capacity of 200 m of thick cable (from Table 5.1) = 1.53 A
Max. current capacity of 6 m of drop line (from Table 5.3) = 0.75 A
Total current of devices connected to drop line = 0.1 A
Therefore, this configuration allows power supply to all stations.
Table 5.3
Maximum Current Capacity Corresponding to
the Drop Line Length
Drop line length (m)
0.30
0.90
1.50
2.25
3.00
4.50
6.00
Max. current (A)
3.00
3.00
3.00
2.00
1.50
1.00
0.75
Slave station
0.1A
Network
power supply
unit
Termination
resistance
Termination
resistance
1.0A
0.15A
0.05A
0.25A
Master station
Slave station
Slave station
Slave station
200m
