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(4) A load momentarily turns on from off when the system is powered off
(transistor output).
Case
Cause
When an inductive load is connected, 2) Load may turn on from off due to a diversion of back EMF at 1) Shutoff.
Action
Take one of two actions shown below.
Action 1: To suppress the back EMF, connect a diode to 3) parallel to the load where back EMF is generated.
Action 2: Configure another current path by connecting a diode across positive and negative of the external power supply. When taking the
action described in "A load momentarily turns on when powering on the external power supply" ( Page 77, Section 8.2 (3)) at a time,
connect a diode parallel to C1 and R1.
For the following source output modules, take Action 1 on the above due to no effect of Action 2 by the characteristics of the external power
supply circuit.
•LY40PT5P
•LY41PT1P
•LY42PT1P
•LH42C4PT1P
ON
OFF
2)
3)
Y0
Y1
COM
12/24VDC
Back EMF
Transistor
output module
Sink type output
1) Shut off
Load
Load
ON
OFF
2)
3)
Y0
Y1
COM
0V
Back EMF
Transistor
output module
Source type output
1) Shut off
Load
Load
Load
Back EMF
Load
Back EMF
Sink type
output
Source type
output
Load
Load
Back EMF
ON
OFF
2)
3)
Y0
Y1
COM
12/24VDC
D1
C1
R1
D1 is in the following status.
Reverse voltage VR (VRM) Approximately 10times higher than
the rated voltage in the specifications
Forward current IF (IFM) More than twice as much as
the maximum load current (common)
in the specifications
2A/1 common 4A or more
24 VDC
Approximately 200V
1) Shut off
Example
Example
Sink type output