IMO Precision Controls K7 Series User Manual page 222

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
Input signal
doesn' t turn off.
External device
Input signal
doesn' t turn off.
(Neon lamp
may be still on)
External device
Input signal
doesn' t turn off.
External device
Input signal
doesn' t turn off.
R
External device
Input signal
doesn' t turn off.
E1
Cause
Leakage current of external device
(Such as a drive by non-contact switch)
AC
C
Leakage current
R
~
Leakage current of external device
(Drive by a limit switch with neon lamp)
AC
C
Leakage current
R
~
Leakage current due to line capacity of
wiring cable.
Leakage current
~
Leakage current of external device
(Drive by switch with LED indicator)
DC
Leakage current
Sneak current due to the use of two
different power supplies.
DC
L
E2
E1 > E2, sneaked.
Connect an appropriate register and capacity,
which will make the voltage lower across the
terminals of the input module.
input
CR values are determined by the leakage current
value.
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 input module terminal and common terminal.
Use only one power supply.
Connect a sneak current prevention diode.
input
E1
E
11-９
Corrective Actions
AC
input
C
R
~
AC
input
~
DC
input
R
DC
input
L