11.
TROUBLESHOOTING
11.4.2 Faults in the output circuit
Faults concerning output circuits and the corrective actions are explained.
Situation
An excessive voltage is
Example
applied to the load when
1
output is off.
Example
Load does not turn off.
2
(Triac output)
Table 11.3 Faults with the output circuit and the corrective actions
Cause
• When the load is subjected to half wave
rectification inside
(Solenoids have these types.)
A1SY22
Output module
• When the polarity of the power supply is [1], C
is charged, and when the polarity is [2], the
voltage charged in C + voltage of the power
supply are applied to the both ends of D1.
The maximum value of the voltage is about
2.2E.
• Leak current caused by built-in noise
suppressor
A1SY22
Output module
Leakage current
• Connect a resistor with several tens to
[1]
D1
Load
[2]
• Connect a resistor to the both ends of the
Load
11 - 24
Countermeasure
several hundreds of k
to the both ends of
the load.
With this kind of usage, there is no problem
with the output element, but the diode built-
in to the load may deteriorate and burn-out.
Resister
Load
load.
When the wiring distance from the output
card to the load is long, be aware of the risk
of a leak current due to line capacity.
Resister
Load