Rockwell Automation System Design for the Control of Electrical Noise - Manual (Page 112)

Publication GMC-RM001A-EN-P — July 2001
A-10 Noise Control Supplement
In Figure A.8, 6.0V common-mode noise spikes are seen at the +24V
dc terminal relative to ground.
Figure A.8
20A, 24V dc PSU (ungrounded, no-load)
In Figure A.9 the noise amplitude is reduced to around 500mV pk,
adequate for general-purpose, dirty loads.
Figure A.9
Grounded common
6.0V pk
Sitop Power 20 with 3 phase input - no load
Common Mode Noise +24 Volts to Backplane
10V
8
6
4
2
0
-2
-4
-6
-8
-10V
ms -1 0 1 2 3 4 5 6 7 8 9
500 mV pk
Sitop Power 20 with 3 phase input - Common grounded
Common Mode Noise +24 Volts to Backplane
10V
8
6
4
2
0
-2
-4
-6
-8
-10V
-1 0 1 2 3 4 5 6 7 8 9 µs