Using Suppression Circuits; Protecting Dc Transistors; Diode Suppression For Dc Transistor Outputs; Zener Diode Suppression For Dc Transistor Outputs - Siemens SIMATIC S7-200 System Manual

Installing an S7-200 PLC
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 include zener-controlled clamping that is
adequate for many installations. Use external suppression diodes for either large or
frequently switched inductive loads to prevent overpowering the internal circuits.
Figure 2-13 and Figure 2-14 show typical applications for DC transistor outputs.
36 V
Figure 2-13
36 V
Figure 2-14
2-16
+VDC

Diode Suppression for DC Transistor Outputs

+VDC
[a]

Zener Diode Suppression for DC Transistor Outputs

[a]
[a] IN4001 diode or
Inductor
[b]
[a] IN4001 diode or
[b] 8.2 V zener, 5W
Inductor
S7-200 Programmable Controller System Manual
equivalent
equivalent
A5E00066097-02