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Chapter 4 Troubleshooting
4-5
4.3.2 Trouble types and measures of output circuit
The followings describe the examples and measures of troubles.
Phenomena
Causes
Measures
Excessive
voltage is
allowed to
load when
output
contact is off
If load contains half-wave rectification(solenoid valve
may have it)
If the polarity is
←
, C is charged while the v
power voltage charged to C is allowed to both ends
of diode(D). when the polarity is
↑
. The max. voltage
is approx. 2
√
2 .
Note) when using it as the above, the output element
does not have any problem but the performance of
diode(D) in load may be reduced, probably
causing a trouble.
Connect a dozens ~ several hundreds k
Ω
resistor to a
load in parallel.
Load can not
be off
Leakage current from surge absorbing circuit
connected to an output element in parallel
Connect a dozens of k
Ω
resistor or CR of which
impedance is equal to the resistance to load in parallel.
Note) If the length of wiring from output module to load is
long, it may have leakage current from capacity of
cables.
Abnormal
time when
load is a C-R
type timer
Leakage current from surge absorbing circuit
connected to an output element in parallel.
Operate the C-R type timer by mediating a relay.
Use other one but a C
−
R type timer.
Note) A timer’s internal circuit may have half-wave
rectification
C
R
~
Load
Leakage current
Output
C
R
~
Load
Leakage current
Output
R
Load
R
Load
C
~
X
T
Timer
Output
C
R
~
←
↑
load
D
C
R
~
Load
R
D