Protection Of Transistor And Noise Suppression - FATEK FBS Series Manual

7.5.2 Protection of Transistor Output and Noise Suppression
The transistor output in FB
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 already includes Zener diode for counter-electromotive force, which is sufficient for
S
PLC Relay output
Inductive load
Suppress by a diode (for low power)
PLC Relay output
Inductive load
Suppress by a diode + Zener (high power and frequent ON/OFF)
VDC
D
VDC
D
ZD
H 7 - 8
D : 1N4001 diode or
equivalent device
D : 1N4001 diode or
equivalent device
ZD : 9V Zener, 5W