External Wiring Precautions - Mitsubishi FX3U SERIES User Manual

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

20.9.4 External wiring precautions

1. Protection circuit for load short-circuits
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. Micro current load
The PLC's internal Triac output circuit is equipped with a turn-off C-
R absorber. When connecting a very low current load of "0.4VA/
100V AC or less or 1.6 VA/200V AC or less", please connect a
surge absorber 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 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
Approx. 0.1µF
Approx. 100 to 200Ω
Model name
20 FX-16/32E*-*-TB (Terminal Block)
Load
Fuse
Micro current load
U
Manufacturer
Rubycon Corporation 250MCRA104100M B0325
Interlock
U
U
PLC output
element
*
Bad
U
*
Good
U
*
U
20.9 FX-16EYS-TB
0 to 7
COMn
Terminal block
Surge
absorber
Model name
Forward limit
Forward
Reverse
Reverse limit
*
U
429
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