6 WIRING
6.6 Output Wiring
119
6
Wiring precautions
■Protection circuit for load short-circuiting
■Contact protection circuit for inductive loads
When an inductive load is connected, connect a diode (for commutation) in parallel with the load as necessary.
The diode (for commutation) must comply with the following specifications.
■Interlock
For loads such as forward/reverse contactors, etc., where a hazardous condition could result if switched ON simultaneously,
an external interlock should be provided for interlocking along with an interlock in the PLC program, as shown below.
A short-circuit at a load connected to an output terminal could cause burnout at the output device or the PCB.
To prevent this, a protection fuse should be inserted at the output. Use a load power supply capacity that is at least 2
times larger than the load current.
Standard
Reverse voltage 5 to 10 times as high as the load voltage
Forward current Load current or larger
PLCs
Y
COM0
Load
Fuse
Sink output type
Y
+V0
PLCs
Load
Fuse
Source output type
PLCs
Inductive load
Fuse
Sink output type
Y
COM0
PLCs
Inductive load
Fuse
Source output type
Y
+V0
+-
Forward rotation
Reverse rotation
Sink output type
Interlock
PLC output
element
Limit of forward
rotation
Limit of reverse
rotation
-
+
Forward rotation
Reverse rotation
Source output type
Interlock
PLC output
element
Limit of forward
rotation
Limit of reverse
rotation
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