Fuji Electric MICREX-SX series SPF - Protection of Transistor Output and Noise Suppression

3-14
Section 3 Specications
(3) Protection of transistor output and noise suppression
The transistor output in SPF already includes Zener diode for counter-electromotive force, which is sufcient for low power
inductive load and medium frequency of ON/OFF application. In conditions of high power or frequent ON/OFF, please construct
another suppression circuit to lower noise interference and prevent voltage from exceeding the limit or overheating that may
damage the transistor output circuit.
PLC Relay output
Inductive load
VDC
D
Suppress by a diode (for low power)
PLC Relay output
Inductive load
VDC
ZD
D
Suppress by a diode + Zener (high power and frequent ON/OFF)
D: 1N4001 diode or
equivalent device
D: 1N4001 diode or
equivalent device
ZD: 9V Zener, 5W