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(4) Precautions for using the triac output module
(a) Measures against back EMF
Take measures against back EMF to the side where the load is connected if the wiring distance from the output
module to the load is long.
If not, the surge suppressor in the output module may not work effectively.
Example Method for selecting elements Remarks
Capacitor + Resistor
method (CR
method)
Refer to the following for constants of the
capacitor and resistor. Note that the
following values may differ depending on a
nature of the load and a variation of
characteristics of it.
• Capacitor: 0.5 to 1(µF) against load
current of 1A
• Resistor: 0.5 to 1() against power
supply voltage of 1V
Use a capacitor whose withstand voltage is
equal to or more than the rated voltage.
Use a capacitor having no polarity.
If a load is a relay or solenoid, the recovery
time delays.
Varistor method
Select a cut-off voltage (Vc) for the varistor
to meet the following condition.
• Vc > Power supply voltage × 1.5(V) × √2
This method is not effective when the Vc is
too high.
The recovery time delays slightly.
Capacitor
Resistor
Inductive
load
Varistor
Inductive
load