Rockwell Automation Allen-Bradley MicroLogix 1000 Instructions D'installation page 12

Installation Instructions
MicroLogix 1000 Programmable
Controllers
Surge Suppression
Inductive load devices such as motor starters and solenoids require the use of
some type of surge suppression to protect the controller output contacts.
Switching inductive loads without surge suppression can significantly reduce the
life expectancy of relay contacts. By adding a suppression device directly across
the coil of inductive devices, you prolong the life of the output circuits. You also
reduce the effects of radiated voltage transients and prevent electrical noise from
radiating into system wiring and facility.
The following diagram shows an output with a suppression device. We
recommend that you locate the suppression device as close as possible to the load
device.
+ dc or L1
VAC/VDC
OUT 0
OUT 1
OUT 2
ac or dc OUT 3
Outputs
OUT 4
OUT 5
OUT 6
OUT 7
COM
If you connect a micro controller FET output to an inductive load, we recommend
that you use an 1N4004 diode for surge suppression, as shown in the illustration
on page 11.
10
Snubber
dc COM or L2