Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 424)

Section 7C
Power Distribution and Wiring Guidelines
7C-6
Figure 7C.5
Location of Noise Suppressors
YES
Suppressor close to source,
transient current does
not circulate through
the cables
NO
Transient current circulates
through the cables and
generates interference
Noise
Filter
+V
+V
Noise
Filter
Noise
Source
Noise
Source
PE
PE
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Spike Voltage Noise Suppression
Spike voltage is generated when contacts in an inductive circuit open. To
reduce spike voltage, connect a noise suppressor in parallel with the load.
This suppresses spike voltage as shown in Figure 7C.6. This also prevents
arcing between the contacts due to spike voltage, thereby protecting both
the contacts and the internal circuit of the solid state output.
Figure 7C.6
Spike Voltage Noise Suppressing
Noise Suppressor
100 mH
Inductive
Load
switch opened
100V ac
Voltage waveform
Current waveform
4.5A p
141v p
SW
-4.5A
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