Rockwell Automation System Design for the Control of Electrical Noise - Manual (Page 57)

Publication GMC-RM001A-EN-P — July 2001
Contact Suppression 6-5
The waveform below displays the effects of an RC suppressor added
across the coil on the noise shown in Figure 6.6. Peaks are reduced to
6.4V with significant reduction in duration. Refer to Figure 6.3 (upper)
for example of RC suppressor across a coil.
Figure 6.7
Effects of RC suppressor mounted at the load
The waveform below displays the effects of a flywheel diode across
the coil (refer to Figure 6.4, upper). The peak voltage is reduced to
0.9V.
Figure 6.8
Effects of Flywheel Diode at the load
6.4 mV pk
Source Omron PSU AC Neutral
DC floating, RC suppressor at Relay coil
(No difference at contact)
-10V
-8
-6
-4
-2
0
2
4
6
8
10V
µs -1 0 1 2 3 4 5 6 7 8 9
µs
930 mV pk
Source Omron PSU AC Neutral
DC floating, Diode at Relay coil
-10V
-8
-6
-4
-2
0
2
4
6
8
10V
-1 0 1 2 3 4 5 6 7 8 9