Rockwell Automation System Design for the Control of Electrical Noise - Manual (Page 103)

Publication GMC-RM001A-EN-P — July 2001
Appendix
A
Noise Control Supplement
Chapter Objectives This appendix is designed to offer additional information on specific
topics related to electrical noise control. The topics include:
• Grounding cable shields
• Wire segregation test results
• Switch-mode DC power supplies
• Using a dynamic braking contactor
• Bonding surfaces
Grounding Cable Shields This section describes different methods for grounding cable shields.
Pigtails
To form a pigtail and attach a flying ground lead:
1. Pull and twist the exposed shield after separation from the
conductors into a braid (often referred to as a pigtail).
2. Solder a flying lead to the braid to extend its length.
Refer to the table below for guidelines on when to use this cable
shield grounding method.
Pigtails are acceptable for cables: Pigtails are not acceptable for cables:
Less than 1 m (39 in.) and confined to the
panel Greater than 1 m (39 in.) or extending
beyond the panel
In clean zones
In very-dirty zones
With very noise sensitive signals (for
example, registration or encoder cables)
That require strain relief