Mitsubishi QX10 User Manual page 138

11 I/O MODULE TROUBLESHOOTING
Table 11.2 Output Circuit Problems and Corrective Actions (Continued)
Condition
The load • If the load current is insufficient (lower than
does not
turn off.
(triac
output)
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Cause
25mA), the triac does not operate, causing the
load current to flow into a phototriac as shown
below.
If an inductive load is connected in this
condition, the load may not turn off because
surge at the time of off is applied to the
phototriac.
QY22
Phototriac
Control
circuit
• Connect a resistor to both ends of the load so
that the load current of approx. 100mA flows
and the triac operation is stable.
Resistance value ≤ Voltage across the load /
100mA
Surge suppressor
(Example)
When using 100VAC (output voltage), for
instance, calculate the resistance value from
the formula below.
100VAC / 100mA = 1kΩ
Load
Resistance value = 1kΩ
Triac
MELSEC-Q
Corrective action
Resistor
Load
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