Faults In The Output Circuit - Mitsubishi Q2ACPU User Manual

22. TROUBLESHOOTING

22.5.2 Faults in the output circuit

Faults concerning output circuits and the corrective actions are explained.
Situation
An excessive voltage
is applied to the load
when output is off.
(Triac output)
Load does not turn
OFF.
(Triac output)
Load turns OFF with a
delay.
(Triac output)
When load is CR type
timer, the time limit
fluctuates.
(Triac output)
Faults in the output circuit
Cause
• When the load is subjected to half wave
rectification inside
(Solenoids have these types.)
• 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 supressor
• Leakage current due to surge suppressor for the
load.
• Connect a resistor at several tens to several
hundred of k
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.
• Connect a resistor to the both ends of the load.
When the wiring distance from the output
module to the load is long, be aware of the
risk of a leak current due to line capacity.
• Disconnect the surge suppressor from across the
loads, leaving only the resistance.
When the wiring distance from the output
module to the load is long, be aware of the
risk of a leak current due to line capacity.
• Connect a resistance between the CR timer
terminals.
In some timers, internal circuit may be half
wave rectification type, so the caution as to
the example 1 is necessary here.
When the wiring distance from the output
module to the load is long, be aware of the
risk of a leak current due to line capacity.
22 - 49
Countermeasure
to the both ends of the load.