BENSHAW RSi SG Series, Instruction Manual

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Chapter 3 - Installation
3-12
- Use a shielded motor cable that is grounded over a large surface area at both ends. The shield on this
cable should be uninterrupted. If a shielded motor cable cannot be used, the unshielded motor lines should
be laid in a metal conduit or duct which is uninterrupted and grounded at both ends.
When selecting shielded cable for use as motor leads it is important to select a cable that is designed for
operation at the frequencies and power levels involved with a variable frequency drive. Improper selection
of motor cables can cause high potential to exist on the shield. This could cause damage to the drive or
other equipment and can pose a safety hazard.
Many cable manufactures have shielded drive cable available. The following cables are acceptable for this
purpose: OLFlex Series 150CY, 110CY, 110CS, 100CY, 100CS, and 540CP. Siemens CordaflexSM is also
acceptable. Some of these cables are VDE-approved only; others carry VDE, UL, CSA, or a combination of
these ratings. Be sure to confirm that the cables meet the appropriate local regulatory requirements.
OLFlex cables are available from OLFlex Wire & Cable, 30 Plymouth Street, Fairfield NJ 07004,
800-774-3539
Cordaflex cables are available from Siemens Energy and Automation, Inc., Power Cables, 3333
State Bridge Road, Atlanta GA 30202, 800-777-3539
- If the installation requires the use of an output reactor, the reactor, as with a line filter, should be placed as
close as possible to the drive.
- Low voltage control wires longer than 1 meter (3ft) must use shielded cable and the shield must be
terminated at the proper CM connection. Note that the connection to the CM rather than earth ground is
allowed because the RSi SG drive has isolated control inputs. If the signal run exceeds 9 meters (30ft), a 0-
20mA or 4-20mA signal should be used as it will have better noise immunity than a low-level voltage signal.
- Other loads connected to the power source may produce voltage transients (spikes) that may interfere with
or damage the drive. Input line reactors or input filters can be used to protect the drive from these transients.
- If the drive is operated from switchgear devices or is in close proximity to switchgear devices (in a
common cabinet), the following procedures are recommended as a precaution to prevent these devices from
interfering with the drives operation.
- Wire the coils of DC devices with freewheeling diodes. The diodes should be placed as close
as possible to the physical coil of the device.
- Wire the coils of AC devices with RC type snubber networks. Place the snubber as close as
possible to the physical coil of the device.
- Use shielded cables on all control and monitoring signals.
- Route distribution cables (for example, power and contactor circuits) separately from the drive's
control and monitoring signal cables.