Specifications

Installing an S7-200 PLC
2-16
S7-200 Programmable Controller System Manual
C79000-G7076-C233-01
2.4 Using Suppression Circuits
General Guidelines
Equip inductive loads with suppression circuits that limit voltage rise on loss of
power. Use the following guidelines to design adequate suppression. The
effectiveness of a given design depends on the application, and you must verify it
for a particular use. Be sure all components are rated for use in the application.
Protecting DC Transistors
The S7-200 DC transistor outputs contain zener diodes that are adequate for many
installations. Use external suppression diodes for either large or frequently
switched inductive loads to prevent overpowering the internal diodes. Figure 2-12
and Figure 2-13 show typical applications for DC transistor outputs.
+VDC
[a] IN4001 diode or
equivalent
[a]
Inductor
Figure 2-12 Diode Suppression for DC Transistor Outputs
+VDC
[a] IN4001 diode or
equivalent
[a]
Inductor
[b]
[b] 8.2 V zener, 5W
Figure 2-13 Zener Diode Suppression for DC Transistor Outputs