Rockwell Automation Publication 20B-IN019E-EN-P - July 2013
23
PowerFlex 700 Adjustable Frequency AC Drive – Frames 0…6
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 that the motor is from the drive without the addition of
motor protective devices such as terminator networks. Refer to the Reflected
Wave topic 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 must 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.
Other types of shielded cable are available, but the selection of these types can
limit the allowable cable length. Particularly, some of the newer cables bundle 4
conductors of THHN wire and wrap them tightly with a foil shield. This
construction can greatly increase the cable charging current required and reduce
the overall drive performance. Unless specified in the individual distance tables as
tested with the drive, these cables are not recommended and their performance
against the lead length limits supplied is not known. See
Table 3
.
Table 3 - Recommended Shielded Wire
Location
Rating/Type
Description
Standard
(Option 1)
600V, 90 °C (194 °F)
XHHW2/RHW-2 Anixter
B209500-B209507, Belden
29501-29507, or equivalent
• Four tinned copper conductors with XLPE insulation.
• Copper braid/aluminum foil combination shield and tinned
copper drain wire.
• PVC jacket.
Standard
(Option 2)
Tray rated 600V, 90 °C
(194 °F) RHH/RHW-2 Anixter
OLF-7xxxxx or equivalent
• Three tinned copper conductors with XLPE insulation.
• 5 mil single helical copper tape (25% overlap min.) with three
bare copper grounds in contact with shield.
• PVC jacket.
Class I & II;
Division I &
II
Tray rated 600V, 90 °C
(194 °F) RHH/RHW-2 Anixter
7V-7xxxx-3G or equivalent
• Three bare copper conductors with XLPE insulation and
impervious corrugated continuously welded aluminum armor.
• Black sunlight resistant PVC jacket overall.
• Three copper grounds on #10 AWG and smaller.
