VYPER
™
VARIABLE SPEED DRIVE
INSTALLATION
100-210 IOM (
JUL
09)
Page 23
POWER WIRING
Shock Hazard! Use appropriate
sized copper wire only. Aluminum
wiring is not acceptable for use in
the Vyper unit. Use of improper wiring may cause serious
injury or damage to the unit.
Size power wiring conductor and ground wiring for the Vyper
™
in accordance with local and the National Electrical Code
(NEC), in addition to all applicable industrial safety regula-
tions. Copper wire is required for all power wiring connected
to the system. Aluminum wiring is NOT acceptable for use
The general specification of the wire is also dictated by the
environment in which the wire is used. The Frick Vyper
™
is a
NEMA 4 indoor-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.
GROUNDING
S h o ck H a z a rd ! Pe r i o d i c a l ly
inspect the integrity of ground
connections. Perform maintenance
on faulty grounding immediately upon discovery. Failure
to do so may result in serious injuries and poor system
performance.
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
700 / 572HP = / > 4/0
912 / 783HP = / > 250 MCM
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
13. 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.
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.
Figure 13 - Ground Circuit
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. In addition to local and national codes and stan-
dards, follow these additional requirements:
•
Base
wire gauge requirements on 167°F (75°C).
•
Allow a spacing of 12 in. (30 cm) between control wiring
and power wiring for every 33 feet (10 m) of length and
do not use long parallel runs.
NOTE: If power wiring is unshielded, it must be in
metallic or PVC coated metallic conduit.
•
Use only cable with insulation thickness of 15 mil
(0.015 in. or .038 mm) or more.
•
Use copper wire only; aluminum power wiring is not
permitted.
•
Do not reduce wire gauge if using higher temperature
wire.
UNSHIELDED CABLE
Use of unshielded cable is acceptable when the cable is
separated from sensitive circuitry. An acceptable example
of unshielded wiring is THHN or TWHN or similar wire. This
wiring is only acceptable in dry environments, 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 mil (0.015 in. or .038 mm) of insulation and
not have large variations in insulation concentricity.
SHIELDED CABLE
Shielded cable is superior to the unshielded cable and
provides all the benefits of the unshielded but also prevents
against AC drive noise by the use of a braided copper shield.
Use shielded cable 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.
When shielded cable is used, the cable requires a minimum
of 75% braided shield coverage. An additional foil shield can
enhance noise containment. The CONTROL WIRING section
describes the factory recommended power cables.
