External Wiring Precautions - Mitsubishi FX3G SERIES User Manual

FX Series Programmable Controllers
3G
User's Manual - Hardware Edition

12.1.3 External wiring precautions

1. 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.
2. Contact protection circuit for inductive loads
An internal protection circuit for the relays is not provided for the relay output circuit in the extension blocks. 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 the product
life.
1) DC circuit
Connect a diode in parallel with the load.
The diode (for commutation) must comply with the following
specifications.
Item
Reverse voltage
Forward current
2) AC circuit
Connect the surge absorber (combined CR components such as a surge killer and spark killer, etc.)
parallel to the load.
Select the rated voltage of a surge absorber that is suitable
for the load being used. Refer to the table below for other
specifications.
Item
Static electricity capacity Approx. 0.1 F
Resistance value
Reference
Manufacturer
Okaya Electric Industries Co., Ltd. CR-10201
3. 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 the PLC's internal programs as shown to
the right.
4. In-phase
PLC output contacts (*) should be used in an "in-phase"
manner.
Guide
5 to 10 times the load voltage
Load current or more
Standard
Approx. 100 to 200
Model name
12 Output Wiring Procedures
12.1 External Wiring for Relay Output Type
Load
Fuse
Inductive load
PLC output
contact
(for commutation)
Inductive load
PLC output
contact
Manufacturer
Rubycon Corporation
Inter- Limit of normal
lock rotation
PLC output
contact
Limit of reverse
PLC output
rotation
contact
*
Bad
*
Good
*
11
12
Y 0
COM1
PLC
13
14
Diode
15
16
Surge
absorber
17
Model name
250MCRA104100M B0325
18
Normal
rotation
Reverse
rotation
19
*
20
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