Rockwell Automation 1797-Series ControlNet Ex Media Plannng Installation Manual - Manual (Page 37)

Publication CNET-IN003A-EN-P - January 2006
Plan a ControlNet Ex Media System 2-15
When you run cable inside an enclosure, route conductors external to
all raceways in the same enclosure, or in a raceway separate from
Category-1 conductors.
Surge Suppression
Transient electromagnetic interference (emi) can be generated
whenever inductive loads such as relays, solenoids, motor starters, or
motors are operated by hard contacts such as push-button or selector
switches. These wiring guidelines assume you guard your system
against the effects of transient emi by using surge-suppressors to
suppress transient emi at its source.
Inductive loads switched by solid-state output devices alone do not
require surge suppression. However, inductive loads of ac output
modules that are in series or parallel with hard contacts require
surge-suppression to protect the module output circuits as well as to
suppress transient emi.
Ferrite Beads Ferrite beads provide additional suppression of transient emi.
Fair-Rite Products Corporation manufactures a ferrite bead
(part number 2643626502) that can be slipped over Category-2 and
Category-3 (RG-6 type trunk cable) conductors. You can secure them
with heat-shrink tubing or tie-wraps. A cable transient emi induced
onto the cable can be suppressed by a ferrite bead located near the
end of the cable. The ferrite bead will suppress the emi before it
enters the equipment connected to the end of the cable.
Required Ferrite Beads
Five ferrites come with each ControlNet Ex adapter. Four are identical
and are for use on the ControlNet Ex trunk cable (two for Segment 1
and two for Segment 2). The fifth ferrite is longer. You use this ferrite
on the adapter power cable.
Route Your Cable At Least From Noise Sources of This Strength
0.08 m (3 in.) Category 1 conductors of less than 20 A
0.15 m (6 in.) ac power lines of 20A or more, up to 100 KVA
0.6 m (24 in.) ac power lines greater than 100 KVA