Rockwell Automation SP600 AC Drive User Manual Version 1.0 - Manual (Page 56)

4-2 SP600 AC Drive User Manual
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 should 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 should be given in
installations with sensitive equipment such as weigh scales,
capacitive proximity switches, and other devices that may 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 may also help reduce shaft voltage and induced
bearing currents for some applications. In addition, the increased
impedance of shielded cable may help extend the distance that the
motor can be located from the drive without the addition of motor
protective devices such as terminator networks.
Consideration should 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 should 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. See
table 4.1.
Other types of shielded cable are available, but the selection of
these types may limit the allowable cable length. Particularly, some
of the newer cables twist 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.