Rockwell Automation 1336T Wiring and Grounding Guide, (PWM) AC Drives - Manual (Page 61)

Rockwell Automation Publication DRIVES-IN001M-EN-P - March 2014 61
Best Practices Chapter 4
Shield Termination via Pigtail (lead)
If a shield terminating connector is not available, the ground conductors or
shields must be terminated to the appropriate ground terminal. If necessary, use a
compression fitting for ground conductors and/or shields together as they leave
the cable fitting.
Figure 24 - Terminating the Shield with a Pigtail Lead
Pigtail termination is the least effective method of noise containment, and is not
recommended for these conditions:
• If the cable length is greater than 1 m (3.2 ft) or extends beyond the panel
• If used in very noisy areas
• If the cables are for noise-sensitive signals (for example, registration or
encoder cables)
• If strain relief is required
If a pigtail is used, pull and twist the exposed shield after separation from the
conductors. Solder a flying lead to the braid to extend its length.
Ground Connections Make sure that ground conductors are properly connected to assure safe and
adequate connections.
For individual ground connections, use star washers and ring lugs to make
connections to mounting plates or other flat surfaces that do not provide proper
compression lugs.
If a ground bus system is used in a cabinet, follow the bus bar mounting diagrams.
U (T1)
V (T2)
W (T3)
PE
PE
Flying Lead Soldered
to Braid
Exposed Shield
One or More
Ground Leads
IMPORTANT This is an acceptable industry practice for most installations to minimize stray
common mode currents.