Troubleshooting Examples; Input Circuit Troubles And Corrective Actions - LG MASTER-K 120S Series User Manual

Chapter 11 Troubleshooting

11.4 Troubleshooting Examples

Possible troubles with various circuits and their corrective actions are explained.

11.4.1 Input circuit troubles and corrective actions

The followings describe possible troubles with input circuits, as well as corrective actions.
Condition
Leakage current of external device
(Such as a drive by non-contact switch)
Input signal
doesn't turn off.
Leakage current of external device
Input signal
(Drive by a limit switch with neon lamp)
doesn't turn off.
(Neon lamp
may be still on)
Leakage current due to line capacity of wiring cable.
Input signal
doesn't turn off.
External device
Leakage current of external device (Drive by switch with
Input signal
LED indicator)
doesn't turn off.
External device
Sneak current due to the use of two different power
Input signal
supplies.
doesn't turn off.
E1
E1 > E2, sneaked.
Cause
C
Leakage current
R
~
External device
C
Leakage current
R
~
External device
Leakage current
~
Leakage current
R
L
E2
Connect an appropriate register and capacity,
which will make the voltage lower across the
terminals of the input module.
AC
input
CR values are determined by the leakage current
value.
AC
input
− Recommended value C : 0.1 ~ 0.47 ㎌
R: 47 ~ 120 Ω (1/2W)
Or make up another independent display circuit.
Locate the power supply on the external device
side as shown below.
AC
input
External device
Connect an appropriate register, which will make
the voltage higher than the OFF voltage across the
input module terminal and common terminal.
DC
input
Use only one power supply.
Connect a sneak current prevention diode.
DC
input
E1
11-9
Corrective Actions
AC
input
C
R
~
AC
input
~
DC
input
R
DC
L
E
input