Allen-Bradley MicroLogix 1200 User Manual page 40

3-4 Wiring Your Controller
Output Device
Varistor
Publication 1762-UM001D-EN-P - March 2004
If the outputs are dc, we recommend that you use an 1N4004 diode
for surge suppression, as shown below. For inductive dc load devices,
a diode is suitable. A 1N4004 diode is acceptable for most
applications. A surge suppressor can also be used. See Table 3.2 for
recommended suppressors. As shown below, these surge suppression
circuits connect directly across the load device.
VAC/DC
Out 0
Out 1
Out 2
Out 3
Relay or Solid
Out 4
State dc Outputs
Out 5
Out 6
Out 7
COM
Suitable surge suppression methods for inductive ac load devices
include a varistor, an RC network, or an Allen-Bradley surge
suppressor, all shown below. These components must be
appropriately rated to suppress the switching transient characteristic of
the particular inductive device. See the table on page 3-5 for
recommended suppressors.
Surge Suppression for Inductive ac Load Devices
Output Device
RC Network
+24V dc
24V dc common
IN4004 Diode
(A surge suppressor
can also be used.)
Output Device
Surge
Suppressor