Output Circuit Troubleshooting - Mitsubishi Q01CPU User Manual

12
TROUBLESHOOTING

12.5.2 Output Circuit Troubleshooting

This section explains trouble examples and troubleshooting methods in the output circuit.
Condition
• When load is half-wave rectified inside (This
is typical of some solenoids.)
Excessive
voltage is
applied to load
• When the polarity of the power supply is [1],
when output
the capacitor C is charged. When the polarity
turns off.
is [2], the voltage charged in C plus the power
supply voltage is applied to across D1. The
maximum value of the voltage is approx. 2.2E.
(This usage does not pose problems to the
output components but may deteriorate the
diode built in the load, causing burnout, etc.)
• Leakage current due to the built-in surge
suppressor
Load does not
turn off.(Triac
output)
• The load current is lower than the minimum
load current.
Control
The load is not
turned OFF.
(Triac output)
• 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 surge
at the time of OFF is applied to the phototriac.
Table12.20 Output circuit troubleshooting
Cause
QY22
D1
Output module
Load
QY22
Output module
Load
Leakage current
QY22
Phototriac
circuit
Triac
• Connect a resistor of several ten K
several hundred K
[1]
[2]
• Connect a resistor across the load.
(If the wiring from the output module to the
load is long, be careful since there may be a
leakage current due to the line capacity.)
• Connect a resistor to both ends of a load so
that the load current is higher than the
minimum load current.
Surge suppressor
Load
12.5 I/O Module Troubleshooting
12.5.2 Output Circuit Troubleshooting
Corrective Action
to
across the load.
Resistor
Load
Resistor
Load
Resistor
Load
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