Output Circuit Troubles And Corrective Actions - Mitsubishi Electric MELSEC iQ-R Series User Manual

9.3

Output Circuit Troubles and Corrective Actions

Excessive voltage is applied to the load when the output is off (triac output).
Cause The load is half-wave rectified internally. (In some cases this is true of solenoids.)
Triac
output module
When the polarity of the power supply is as shown in (1), C is charged. When the polarity is as shown in [2], the voltage charged in C plus
the line voltage are applied across D1. Maximum voltage is approx. 2.2E. (If a resistor is used in this way, it does not pose a problem to the
output element. But it may cause the diode, which is built into the load, to deteriorate, resulting in a fire, etc.)
Action Connect a resistor (several tens to hundreds of k) across the load.
Resistor
Load
The load does not turn off (triac output).
■Case 1
Cause A leakage current occurred due to a built-in surge suppressor.
Triac
output module
Action Connect a resistor across the load. (Note that a leakage current may occur due to the line capacity when the wiring distance from the
output module to the load is long.)
Resistor
Load
(1)
D1
Load
(2)
Load
Leakage current
9 TROUBLESHOOTING
9.3 Output Circuit Troubles and Corrective Actions
9
123