Filter
Top Products
75
CHAPTER 8 TROUBLESHOOTING
8
8.2 Troubleshooting for Output Circuit
8.2 Troubleshooting for Output Circuit
(1) When the output is off, excessive voltage is applied to the load (triac output).
(2) The load does not turn off (triac output).
(a) Case 1
Case
Cause
• The load is half-wave rectified internally. (In some cases this is true of solenoids.)
• 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.
Case
Cause
• A leakage current occurred due to a built-in surge suppressor.
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.)
[1]
[2]
D1
TRIAC
output module
Load
Load
Resistor
Leakage current
Load
TRIAC
output module
Load
Resistor