96BInstallation
3.4 Wiring guidelines
S7-1200 Programmable controller
60
System Manual, 11/2011, A5E02486680-05
Typical suppressor circuit for DC or relay outputs that switch DC inductive loads
A
B
①
1N4001 diode or equivalent
②
8.2 V Zener (DC outputs),
36 V Zener (Relay outputs)
③
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.
Typical suppressor circuit for relay outputs that switch AC inductive loads
MOV
①
0.1 μ F
②
100 to 120 Ω
③
Output point
When you use a relay output to switch 115 V/230
VAC loads, place the appropriately rated resistor-
capacitor-metal oxide varistor (MOV) circuit across
the AC load. Ensure that the working voltage of the
MOV is at least 20% greater than the nominal line
voltage.