Rockwell Automation System Design for the Control of Electrical Noise - Manual (Page 78)

Publication GMC-RM001A-EN-P — July 2001
9-2 High Speed Registration Inputs
Noise Reduction Methods This section provides installation guidelines for reducing noise
coupling into high speed registration inputs.
Wiring
Follow these guidelines to reduce noise coupling in wiring:
• Always use shielded cable.
• Connect shields at both ends and at the circular section.
• Always run the cable in a clean zone.
• Segregate the cable as far as practical from dirty and (especially)
very-dirty wiring.
• Always make cable runs as short as possible.
Power
Follow these guidelines to reduce noise coupling in power supplies:
• The power supply should be as clean as possible.
• Use a filter if a switch-mode supply is used (refer to the chapter
Filtering Noise for more information).
• Obtain +24V dc power from a clean supply and provide a filter
(refer to the chapter Filtering Noise for more information).
• Always ground the common.
Shared Power Supply
Observe the following guidelines when sharing power between the
registration input and other clean loads. Refer to Figure 9.1 for a
shared power wiring diagram.
• Provide a filter just prior to the registration input, even if the +24V
dc supply has a clean rating.
• Mount the filter on a separate DIN rail, especially if a painted
panel is used.