Omron CRT1 - 10-2009, Operation Manual

Page: 123 / 675

99
Power Supply Wiring
Section 3-5
Supplying I/O Power
from Multiple Sources
Supplying I/O power from multiple power supplies instead of from one power
supply enables reducing the line current, reducing the voltage drop, and
decreasing the size of the cable. Using multiple power supplies should also be
considered to increase system safety when power supply errors occur.
3-5-7 Other Precautions
Power Supply Errors
The location of power supplies and the grouping of Slave Units should be con-
sidered based on whether the overall system is to be stopped when a power
supply error occurs.
If it is necessary to prevent the overall system from stopping to ensure system
safety, consider placing power supplies in more than one location and con-
sider the way Slave Units should be grouped when supplying power.
Cost Considerations
Also consider the power supply methods in light of the total cost, including the
following items:
The capacity and number of power supplies, Cable thickness (allowable cur-
rent) and length (voltage drop), System safety, and Wiring work.
1
3 2
I
1
I
2
I
3
4
I
4
Load
Design the wiring so that a sta-
ble power supply voltage is sup-
plied to the end load.
If a stable power supply voltage cannot sup-
plied to the end load, place the power supply
in the middle of the network.
Slave
Slave
Slave
Slave
Load
Load
Load
Power supply
(24 VDC)
Power supply
(24 VDC)
Slave
Power supply
(24 VDC)
Slave Slave Slave
Power supply
(24 VDC)