Rockwell Automation 1770 Industrial Automation Wiring and Grounding Guidelines - Manual (Page 16)

Industrial Automation Wiring and Grounding Guidelines 16
Publication 1770-4.1 – February 1998
Figure 10
Examples of where to use Suppression
12597-I
ac output module
solid-state
L1 L2
1MS
L1
switch
1MS
1M
suppressor
L2
Although the motor starter is an
inductive load, it does not need a
suppressor because it is switched
by a solid-state device.
The motor needs supressors
because it is an inductive load
switched by hard contacts.
ac output module
solid-state
L1 L2
1CR
switch
suppressor
The interposing relay needs a
supressor because it is an inductive
load switched by hard contacts.
contact output module
L1 L2
suppressor
The pilot light needs a supressor
because it is an inductive load
switched by hard contacts.
Example 1:
An ac output module
controls a motor starter
whose contacts control the
motor.
Example 2:
An ac output module
controls an interposing
relay, but the circuit can be
opened by hard contacts.
The relay contacts control
a solenoid.
Example 3:
A contact output module
controls an inductive load.
L1
1CR
1S
suppressor
L2
The solenoid needs a supressor
because it is an inductive load
switched by hard contacts.
pilot light with built-in
step-down transformer
suppressor
suppressor
1MS
1MS
L1
Figure 11 shows typical suppression circuitry for different types of
loads. Allen-Bradley bulletin 700 relays and bulletin 509 and
bulletin 709 motor starters have surge-suppressors for their coils
available as an option. Table C lists some Allen-Bradley products
and their suppressors. See the Allen-Bradley Industrial Control
Catalog for more information on suppressors including Bulletin
1492 surge-suppressor terminal blocks.