IDEC MICROSmart FC6A Series User Manual page 251

Output Protection Circuit
When a motor, solenoid, or similar inductive load is connected, the life of the contact is shortened due to the inrush current and
counter-electromotive force acting on the load. In order to prevent this, set up an output protection circuit outside the FC6A Series
MICROSmart. Choose a protection circuit from (1) through (4) shown below, according to the power supply, and connect the
protection circuit to the outside of the FC6A Series MICROSmart.
For protection of the transistor output of the FC6A Series MICROSmart modules, connect protection circuit (3) shown below to the
transistor output circuit.
Protection Circuit (1)
Output Q
C
R
COM
Protection Circuit (2)
Surge Killer
Output Q
COM
Protection Circuit (3)
Output Q
COM
Protection Circuit (4)
Output Q
COM
This protection circuit can be used when the load impedance is smaller
Inductive Load than the RC impedance in an AC load power circuit.
R: Resistor of approximately the same resistance value as the load
C: 0.1 to 1 µF
This protection circuit can be used for both AC and DC load power
circuits.
Inductive Load
R: Resistor of approximately the same resistance value as the load
C: 0.1 to 1 µF
R C
or
– +
This protection circuit can be used for DC load power circuits.
Inductive Load
Use a diode with the following ratings.
Reverse withstand voltage:
Forward current:
Diode
– +
This protection circuit can be used for both AC and DC load power
circuits.
Inductive Load
Varistor
– +
or
FC6A S MICROS
ERIES
Power voltage of the load circuit  10
More than the load current
U ' M FC9Y-B1722
MART SER S ANUAL
3: I
NSTALLATION AND
W
IRING
3-19