Selecting The I/O Power Supplies - Omron NX Series Hardware User Manual

4 Designing the Power Supply System
= Required Unit power supply capacity of CPU Unit block
= (CPU Unit power consumption + Total power consumption from NX Unit power supply of NX
Units connected to CPU Unit)/NX Unit power supply efficiency of CPU Unit
= 18.3 W + 8.1 W + (0.85 W × 1 + 0.90 W × 4 + 1.20 W × 3)/0.8
= Approx. 36.5 W
The above is the constant power consumption during operation. When you select the power supply,
consider the inrush current that will flow when the power is turned ON.
Refer to Electrical and Mechanical Specifications on page 3-2 for information on inrush current
specifications.
Precautions for Safe Use
Select an external power supply with sufficient capacity by considering the power supply ca-
pacity or inrush current when the power is turned ON that is specified in this manual.
Otherwise, the external power supply may not be turned ON or malfunction due to unstable
power supply voltage.
4-4-2

Selecting the I/O Power Supplies

This section describes how to select the I/O power supplies for the CPU Rack.
Recommended Power Supplies
Use an SELV power supply that meets the following conditions for the I/O power supply.
• Has overcurrent protection.
• Has double or reinforced insulation between the input and output.
• Has an output voltage of 5 to 24 VDC (4.5 to 28.8 VDC).*1
*1. Use an output voltage that is appropriate for the I/O circuits of the NX Units and the connected external devi-
ces.
Recommended Power Supplies: S8VK-S Series (manufactured by OMRON)
Calculating the Required Power Supply Capacity of the I/O Power
Supply for NX Units
Use the calculation method that is described in 4-3-2 Designing the I/O Power Supply from the NX
Bus on page 4-15 and calculate the total current consumption from the I/O power supply and the re-
quired power supply capacity of the I/O power supply.
Unlike the Unit power supply, it is not necessary to use only one I/O power supply to supply power to
all NX Units on the CPU Rack.
Precautions for Safe Use
Select an external power supply with sufficient capacity by considering the power supply ca-
pacity or inrush current when the power is turned ON that is specified in this manual.
Otherwise, the external power supply may not be turned ON or malfunction due to unstable
power supply voltage.
4-24
NX-series NX502 CPU Unit Hardware User's Manual (W629)