External Wiring Precautions - Mitsubishi Electric MELSEQ FX3S Series User Manual

FX Series Programmable Controllers
3S
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 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 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
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
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
Guide
Approx. 0.1 μF
Approx. 100 to 200 Ω
Model name
could result if switched
12 Output Wiring Procedures
12.1 External Wiring for Relay Output Type
Load
Fuse
+
PLC output
contact
(for commutation)
PLC output
contact
Manufacturer
Rubycon Corporation
ON
Interlock
PLC output
contact
PLC output
contact
*
Bad
*
Good
*
Main unit
Y001
COM1
-
Inductive load
Diode
Inductive load
Surge
absorber
Model name
250MCRA104100M B0325
Limit of
normal
rotation
Normal
rotation
Limit of
reverse
rotation
Reverse
rotation
*
111
11
12
13
14
15
16
17
A
B
C