Siemens SIMATIC S7-1200 System Manual page 81

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Typical suppressor circuit for DC or relay outputs that switch DC inductive loads

Typical suppressor circuit for relay outputs that switch AC inductive loads

S7-1200 Programmable controller

System Manual, V4.2, 09/2016, A5E02486680-AK

1N4001 diode or equivalent

8.2 V Zener (DC outputs),

36 V Zener (Relay outputs)

Output point

M, 24 V reference

See table for C value

See table for R value

Output point

In most applications, the addition of a diode (A)

across a DC inductive load is suitable, but if your

application requires faster turn-off times, then the

addition of a zener diode (B) is recommended. Be

sure to size your zener diode properly for the amount

of current in your output circuit.

Ensure that the working voltage of the metal oxide

varistor (MOV) is at least 20% greater than the nomi-

nal line voltage.

Choose pulse-rated, non-inductive resistors, and

capacitors recommended for pulse applications (typi-

cally metal film). Verify the components meet aver-

age power, peak power, and peak voltage

requirements.

Installation

4.4 Wiring guidelines