Rockwell Automation 1336T Wiring and Grounding Guide, (PWM) AC Drives - Manual (Page 81)

Rockwell Automation Publication DRIVES-IN001M-EN-P - March 2014 81
Appendix
A
Motor Cable Length Restrictions Tables
Overview The distances listed in each table are valid only for specific cable constructions
and are not always accurate for lesser cable designs, particularly if the length
restriction is due to cable charging current (indicated in the tables by shading).
When choosing the proper cable, note these definitions.
Unshielded Cable
• Tray cable – fixed geometry without foil or braided shield but including an exterior cover
• Individual wires not routed in metallic conduit
Shielded Cable
• Individual conductors routed in metallic conduit
• Fixed geometry cables with foil or braided shield of at least 75% coverage
• Continuous weld or interlocked armored cables with no twist in the conductors (can have an optional foil shield)
IMPORTANT Certain shielded cable constructions can cause excessive cable charging
currents and can interfere with proper application performance, particularly on
smaller drive ratings. Shielded cables that do not maintain a fixed geometry,
but rather twist the conductors and tightly wrap the bundle with a foil shield,
can cause unnecessary drive tripping. Unless specifically stated in the table, the
distances listed are not applicable to this type of cable. Actual distances for
this cable type can be considerably less.
Type A Motor
• No phase paper or misplaced phase paper
• Lower quality insulation systems
• Corona inception voltages between 850…1000V
Type B Motor
• Properly placed phase paper
• Medium quality insulation systems
• Corona inception voltages between 1000…1200V
1488V Motor
• Meets NEMA MG 1-1998 section 31 standard
• Insulation can withstand voltage spikes of 3.1 times rated motor voltage due to inverter operation
1329 R/L Motor
• AC variable speed motors are control-matched for use with Allen-Bradley drives
• Motor designed to meet or exceed the requirements of the Federal Energy Act of 1992
• Optimized for variable speed operation and include premium inverter grade insulation systems that meet or
exceed NEMA MG1 (Part 31.40.4.2)