Power cable design considerations, Motor cable sizing – Rockwell Automation 6000 PowerFlex Medium Voltage Variable Frequency Drive Installation Instructions User Manual

Page 44

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Rockwell Automation Publication 6000-IN006A-EN-P - April 2014

Chapter 3

Drive Electrical Installation

Power Cable Design
Considerations

Use fire retardant cables for the drive input/output connections.

Shielded or unshielded cable can be used based on the criteria considered by the
distribution system designer and national and local electrical codes.

If shielded power cables are used, connect the shield of the main input/output
power cables with the general grounding point of the drive. Ground the drive
output protective grounding connection separately, and only at the drive side.

Comply with the maximum tensile stress and the minimum curvature radius
recommended by the cable manufacturer.

Do not bundle the input/output cables of the drive together.

The power cable tray must not be less than 300 mm (12 in.).

There must be no gaps where the conduit connects to the cabinet and the ground
bond must be less than 0.1 ohms. Spacing between wire groups is the
recommended minimum for parallel runs of approximately 61 m (200 ft) or less.

All input and output power wiring, control wiring or conduit must be brought
through the conduit entrance holes of the cabinet. Use appropriate connectors to
maintain the environmental rating of the cabinet.

Motor Cable Sizing

Voltage drop in motor leads may adversely affect motor starting and running
performance. Installation and application requirements may dictate that larger
wire sizes than indicated in national and local electrical codes are used.

Wire sizes must be selected individually, observing all applicable safety and
national and local electrical codes. The minimum permissible wire size does not
necessarily result in the best operating economy. The minimum recommended
size for the wires between the drive and the motor is the same as that used if a
main voltage source connection to the motor was used. The distance between the
drive and motor can affect the size of the conductors used.

Consult the Electrical Drawings and appropriate national and local electrical
codes to determine correct power wiring. If assistance is needed, contact your
local Rockwell Automation Sales Office.

IMPORTANT

The power cable distance from the drive to the motor must not be longer than
300 m. If the power cable exceeds 300 m, contact the factory. Configurations
can be provided for longer cable distances, but must be specified at the time of
order.

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