Rockwell Automation 20D PowerFlex 700 Installation Instructions - Frames 7…10 - Manual (Page 31)

Rockwell Automation Publication 20B-IN014H-EN-P - June 2013 31
PowerFlex 700 Adjustable Frequency AC Drive – Frames 7…10
Cable Types Acceptable for 200…600 Volt Installations
A variety of cable types are acceptable for drive installations. For many
installations, unshielded cable is adequate, provided it can be separated from
sensitive circuits. As an approximate guide, allow a spacing of 0.3 meters (1 foot)
for every 10 meters (32.8 feet) of length. In all cases, long parallel runs must be
avoided. Do not use cable with an insulation thickness less than or equal to 15
mils (0.4mm/0.015 in.). Use Copper wire only. Wire gauge requirements and
recommendations are based on 75 °C. Do not reduce wire gauge by using higher
temperature wire.
Unshielded
THHN, THWN or similar wire is acceptable for drive installation in dry
environments provided adequate free air space and/or conduit fill rates limits are
provided. Do not use THHN or similarly coated wire in wet areas. Any wire
chosen must have a minimum insulation thickness of 15 Mils and not have large
variations in insulation concentricity.
Shielded/Armored Cable
Shielded cable contains all of the general benefits of multi-conductor cable with
the added benefit of a copper braided shield that can contain much of the noise
generated by a typical AC Drive. Strong consideration for shielded cable must be
given in installations with sensitive equipment such as weigh scales, capacitive
proximity switches and other devices that can be affected by electrical noise in the
distribution system. Applications with large numbers of drives in a similar
location, imposed EMC regulations or a high degree of communications/
networking are also good candidates for shielded cable.
Shielded cable can also help reduce shaft voltage and induced bearing currents for
some applications. In addition, the increased impedance of shielded cable can
help extend the distance between the motor and drive without the addition of
motor protective devices such as terminator networks. Refer to Reflected Wave
in the Wiring and Grounding Guidelines for Pulse Width Modulated (PWM)
AC Drives, publication
DRIVES-IN001 .
Consideration must be given to all of the general specifications dictated by the
environment of the installation, including temperature, flexibility, moisture
characteristics and chemical resistance. In addition, a braided shield can be
included and be specified by the cable manufacturer as having coverage of at least
75%. An additional foil shield can greatly improve noise containment.
A good example of recommended cable is Belden® 295xx (xx determines gauge).
This cable has four (4) XLPE insulated conductors with a 100% coverage foil and
an 85% coverage copper braided shield (with drain wire) surrounded by a PVC
jacket.