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TROUBLESHOOTING11.
Table 11.3 Faults with the output circuit and the corrective actions (continued)
Situation Cause Countermeasure
Example
3
The load is not
turned off.
(Triac output)
• The load current is lower than the minimum load current.
• When the load current is lower than the minimum load
current of the output module, the triac does not operate since
the load current flows into a phototriac as shown below.
When an inductive load is connected, the load may not be
turned off since the surge at the time of off is applied to the
phototriac.
• Connect a resistor to both ends of a
load so that the load current is higher
than the minimum load current.
Example
4
When load is
CR type timer,
the time limit
fluctuates.
(Triac output)
• Start the relay first, then start the CR-
type timer at the contact.
In some timers, internal circuit may be half
wave rectification type, so the caution as to
the example 1 is necessary here.
Triac
Surge suppressor
Phototriac
Control
circuit
Load
A1SY22
Output module
Leakage current
A1SY22
Output module
CR
timer
Calculate the
constant of the
resistance based on
the load.
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