Rockwell Automation System Design for the Control of Electrical Noise - Manual (Page 58)

Publication GMC-RM001A-EN-P — July 2001
6-6 Contact Suppression
The waveform below displays the effects of a flywheel diode across
the switch (refer to Figure 6.4, lower). The peak voltage is reduced to
0.3V.
Figure 6.9
Effects of Flywheel Diode at the switch
The small additional noise reduction, when the suppressor is fitted
across the switch, is because the wiring between switch and load is
also inductive and creates the same inductive spike.
340 mV pk
Source Omron PSU AC Neutral
DC floating, Diode at Switch
-10V
-8
-6
-4
-2
0
2
4
6
8
10V
µs -1 0 1 2 3 4 5 6 7 8 9