VYPER
™
VARIABLE SPEED DRIVE
INSTALLATION
100-200 IOM (FEB 09)
Page 10
POWER WIRING
Power wiring conductor and ground wiring for the Vyper
™
must be sized in accordance with local and national electrical
codes, in addition to applicable industrial safety regulations.
Copper wire is required for all power wiring connected to the
system.
Aluminum wiring is NOT acceptable.
GROUNDING
Grounding is the most important factor for successful opera-
tion and is also the most overlooked. The NEC states that
control equipment may be grounded by using the rigid conduit
as a conductor. This worked for the earlier relay systems, but
it is not acceptable for electronic control equipment. Conduit
is made of steel and is a poor conductor relative to a copper
wire. Electronic equipment reacts to very small currents and
must have a good ground in order to operate properly; there-
fore,
copper grounds are required for proper operation.
The three phase power brought into the plant must also
have a ground wire,
making a total of four wires.
Due to the noise (EMI) that is generated by VFDs between
the drive output and the motor, increased ground conductor
sizing is necessary to effectively steer this noise to earth
ground.
Required Main Grounding Conductor Size:
305 / 254HP = / > #1-AWG (Copper)
437 / 362HP = / > 2/0 (Copper)
Main ground conductors may be multiple with the total
rating being equal to or greater than the required.
NOTE:
Grounds must be stranded copper and insulated.
In many installations that are having electronic control prob-
lems, this essential wire is usually missing. A good ground cir-
cuit must be continuous from the plant source transformer to
the electronic control panel for proper operation. See Figure
5. Driving a ground stake at the electronic control will cause
additional problems since other equipment in the plant on
the same circuits will ground themselves to the ground stake
causing large ground flow at the electronic equipment.
Figure 5 - Ground Circuit
FUSES AND CIRCUIT BREAKERS
The Frick Vyper
™
can be installed by using either input power
fuses or a circuit breaker. Either configuration must conform
to industrial safety regulations and both local and national
electrical codes.
ACCEPTABlE CABlE TYPES
National and local codes and standards and applicable
safety regulations govern the installation of electrical cable.
The installation must comply to the specifications regarding
disconnect devices, conductor sizes, wire types, and circuit
protection.
Unshielded cable is acceptable if it can be separated from
sensitive circuitry. Allow a spacing of 12 inches for every
33 feet of length. In all cases, long parallel runs must not
be used.
If power wiring is unshielded, it needs to be
in metallic or PVC metallic conduit.
Do not use a cable
insulation thickness of 15 mils (0.015 in) or less.
Use copper
wire only; NO aluminum power wiring is permitted.
Wire
gauge requirements and recommendations are based on 75
degrees C (167°F). Wire gauge is not to be reduced if using
higher temperature wire.
An acceptable example of unshielded wiring is THHN or
TWHN or similar wire. This wiring is only acceptable in dry en-
vironments, provided adequate free air space is provided. Do
not use THHN or similar coated wire in wet or damp locations.
The wire must have at least 15 mils (0.015 in) of insulation
and not have large variations in insulation concentricity.
Shielded cable is superior to the unshielded cable in that it
provides all the benefits of the unshielded but also prevents
against AC drive noise by the use of braided copper shield.
Shielded cable should be used in sensitive installations
such as weight scales, capacitive proximity switches, and
other devices that may be affected by stray electronic noise.
Installations with multiple VSDs should also use shielded
power cable. Shielded cable may also reduce shaft voltage
and bearing currents in some applications.
The general specification of the wire is also dictated by the
environment in which it is used. The Frick Vyper
™
is a NEMA 4
rated VSD and should also have power cable selection to
withstand the local environment. Moisture level, temperature,
flexibility and chemical resistance are all factors which need
to be considered in power wire selection.
A braided shield should be included and have at least 75%
coverage. Also an additional foil shield can enhance noise
containment. The CONTROL WIRING section describes the
factory recommended power cables.
CONTROl WIRING
Vyper
™
packaged systems have all required sensors and
transducers factory mounted. Remote systems must be wired
at the installation site.
Here are some important points to consider for control wiring:
•
Use Copper wire only. Use of Aluminum wiring is not
permitted.
Wire gauge requirements are based on 75°C.
DO NOT reduce wire gauge when using higher tempera-
ture wire.
• Wire with an insulation rating of 600V or higher is recom
-
mended.
• Control and signal wires should be separated from power
wires by at least 1 foot.