Chapter 14 Troubleshooting
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14.4.2 Output Circuit Error Types and Corrective Actions
Here describes the trouble examples of output circuit and its measures.
Phenomena
Causes
Measures
Over voltage
applied to the
load if case of
output contact
OFF
y
In case that the load is semi-sine
inside, (solenoid valve)
y
If power polarity is
←
, C is charged, if
polarity is
↑
, voltage charged to C +power
voltage is applied to both sides of diode(D).
Max. voltage is about 2
√
2 .
Note) If used as above, output element does
not make trouble but the function of diode(D)
built-in the load becomes low which causes
the trouble.
y
Connect several dozens k
Ω
~
hundreds k
Ω
resistance to the load in
parallel.
The load is
not
OFF
y
Leakage current by surge absorption
circuit connected with output element in
parallel
y
Connect CR with several dozens k
Ω
or
equivalent impedance to the load in parallel.
Note) If wiring length is long from
output module to the load, leakage current by
capacity between cables.
Time trouble
in case the
load is C
−
R
type timer.
y
Leakage current by surge absorption
circuit connected with output elements in
parallel
y
Run C-R type timer by Relay.
y
Use the timer except C
−
R type timer.
Note) There is the timer that internal circuit is
semi-sine.
load is not
OFF
(AC)
y
Circulation current by two different
powers
y
If E1< E2, circulated
y
If E1 is Off(E2 On), circulated
y
Double power --> single power.
y
Connect purified current prevention
diode.(as below)
Note) If load is Relay, it is required to connect
reverse voltage absorption diode as dot line
on the above figure..
C
R
Load
Leakage current
Output
C
R
Load
Leakage
current
Output
C
R
Load
R
D
R
Load
R
Load
C
T Timer
Output
E1
Load
E
Output
Output
Load
E
E
C
R
←
↑
Load
D