Installation and Wiring 
 
FPΣ User's Manual 
86 
6.4.2.1  Protective Circuit for Inductive Loads 
With an inductive load, a protective circuit should be installed in parallel with the load. 
When switching DC inductive loads with the relay output type, be sure to connect a diode 
across the ends of the load. 
Using an AC inductive load (relay output type) 
A
 
FPΣ 
1
 
Output terminal 
2
 
Load 
3
 
Surge absorber, e.g. resistance R: 50Ω, 
capacitance C: 0.47μF 
COM
2
1
3
R
C
 
 
 
 
A
 
FPΣ 
1
 
Output terminal 
2
 
Load 
3
 
Varistor 
COM
2
1
3
 
 
 
Using a DC inductive load 
A
 
FPΣ 
1
 
Output terminal 
2
 
Load 
3
 
Diode; reverse voltage (V
R
): 3 × load voltage, 
average rectified forward current (I
0
): ≥ load current 
or more 
COM
2
1
3
 
 
 
 
 
6.4.2.2  Protective Circuit for Capacitive Loads 
When connecting loads with large in-rush currents, connect a protection circuit as shown 
below to minimize their effect. 
A
FPΣ 
1
Output terminal 
2
Load 
3
Resistor 
COM
2
1
3