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Blocks
A block consists of the Unit that supplies the NX Unit power and the range of Units to which that
Unit supplies the NX Unit power.
For example, in the configuration in the following figure there are two blocks in the CPU Rack: the
block with the
CPU Unit which contains the X Bus Unit and the block with the Additional NX Unit
Power Supply Unit.
Internal circuits
End
Cover
NX Unit power supply
Internal
circuits
Internal
circuits
Internal
circuits
NX Unit power supply
Internal
power
supply
circuit
Unit power supply terminals
CPU Unit block
Additional NX Unit Power Supply Unit block
NX Unit connected
to the CPU Unit
X Bus Unit connected
to the CPU Unit
NX Unit connected to the Additional
NX Unit Power Supply Unit
Additional NX Unit Power
Supply Unit
Internal
power
supply
circuit
Unit power supply terminals
NX-series
NX502 CPU Unit
Unit power supply
(24 VDC)
Internal
circuits
Internal
circuits
Internal
circuits
Internal
circuits
Internal
circuits
Internal
circuits
The total of the required Unit power supply capacity for these two blocks is the required power sup-
ply capacity of the Unit power supply for the CPU Rack.
Precautions for Correct Use
Use the same Unit power supply to supply the Unit power to one CPU Rack. If you supply pow-
er from different Unit power supplies, dif
ferences in electrical potential may cause unexpected
currents in the NX Unit power supply, which may result in failure or malfunction.
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Calculation Example
This section provides a calculation example for the configuration example that is given in 4-2-2 Cal-
culation Example for the NX Unit Power Supply on page 4-12.
Name Model Quantity Power consumption/Unit
CPU Unit NX502-1500 1 18.3 W
EtherNet/IP Unit NX-EIP201 1 8.1 W
Additional I/O Power Supply Unit NX-PF0630 1 0.85 W
Digital Input Unit NX-ID3317 4 0.90 W
Relay Output Unit NX-OC2633 3 1.20 W
• The NX Unit power supply efficiency of the CPU Unit is 80%.
In this configuration example, there is only one block, the CPU Unit block.
Required power supply capacity of Unit power supply to CPU Rack
4 Designing the Power Supply System
4-23
NX-series NX502 CPU Unit Hardware User's Manual (W629)
4-4 Selecting External Power Supplies and Protective Devices
4
4-4-1 Selecting the Unit Power Supply