Mitsubishi Electric MELSEC iQ-F FX6U Hardware User Manual page 138

Wiring precautions
■Protection circuit for load short-circuiting
A short-circuit at a load connected to an output terminal could cause burnout at the output element or the PCB. To prevent
this, a protection fuse should be inserted at the output.
Load
Y0
Fuse
COM0
■Contact protection circuit for inductive loads
An internal protection circuit for the relays is not provided for the relay output circuit in this product. It is recommended to use
inductive loads with built-in protection circuits.
When using loads without built-in protection circuits, insert an external contact protection circuit, etc. to reduce noise and
extend product life.
• DC circuit
Connect a diode in parallel with the load.
+
Inductive load
PLC output contact
Diode (for commutation)
The diode (for commutation) must comply with the following specifications.
• Reverse voltage: 5 to 10 times the load voltage
• Forward current: Load current or more
• AC circuit
Connect a surge absorber (CR composite parts like surge killer, spark killer, etc.) parallel to the load.
Inductive load
PLC output contact
Select a surge absorber with voltage rating that is suitable for the output used.
• Electrostatic capacity: Approx. 0.1 μF
• Resistance: Approx. 100 to 200 Ω
■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.
Interlock
PLC output
contact
PLC output
contact
6 WIRING
136
6.6 Output Wiring
PLCs
-
Surge
absorber
Limit of forward
rotation
Forward
rotation
Limit of reverse
rotation
Reverse
rotation