l
For I/O Power Supply
Current
Breaking/fusing
time
6 A 1 min max.
12 A 15 s max.
21 A 5 s max.
30 A 2.5 s max.
Installation Locations for Protective Devices
Install protective devices for the Unit power supply and I/O power supply in the locations that are
shown in the following figure.
External devices
End
Cover
Built-in I/O
Internal
circuits
NX Unit power supply
Unit power supply
terminals
Internal
power
supply
circuit
Unit power
supply
(24 VDC)
NX-series
NX1P2 CPU
Unit
Protective
device
Protective
device
I_unit1
I_ioB
I_unit2
I_io1
I_io2
I/O power
supply
I/O power
supply
Block that the CPU Unit supplies Unit power supply.
Block that an Additional I/O
Power Supply Unit 1 supplies
I/O power supply.
Block that an Additional I/O
Power Supply Unit 2 supplies
I/O power supply.
Block that an Additional NX Unit Power Supply
Unit supplies Unit power supply.
External devices
Power
supply
NX power supply
Unit power
supply terminals
I/O power
supply
terminal
I/O power
supply
terminal
Cn(+V)/0Vn
terminal PNP
(sourcing)
type only
I/O power supply
(24 VDC, etc.)
Additional
NX Unit
Power
Supply Unit
○
○ ○ ○ ○ ○ ○ ○ ○ ○
Protective
device
Protective
device
Protective
device
Additional
I/O Power
Supply
Unit 1
Additional
I/O Power
Supply
Unit 2
However, fewer protective devices may be required when the current consumption of each block does
not exceed the rated current.
An example of this is provided below.
•
Using Unwired Unit Power Supply Terminals
In this example, the current consumption from each power supply is as follows:
Current consumption from Unit power supply: I_unit1 + I_unit2 ≤ Lowest rated current
Current consumption from I/O power supply for NX Units: I_io1+I_io2 ≥ 4 A (rated current for I/O
power supply)
4 Designing the Power Supply System
4-26
NX-series NX1P2 CPU Unit Hardware User’s Manual (W578)
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