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4 Installation & Operation
MN427
Grounding In Europe
, the customer is responsible to ensure ground method conforms to IEC and applicable local
codes. Grounding provisions are inside the motor conduit box for European CE compliance and a ground
hole is provided in the opposite drive end bracket as standard features.
In the USA
consult the National Electrical Code (NEC), Article 430 for information on grounding of motors
and generators, and Article 250 for general information on grounding. In making the ground connection,
the installer should make certain that there is a solid and permanent metallic connection between the
ground point, the motor terminal housing, and the motor frame. A ground hole is provided in the opposite
drive end bracket as standard features.
There are applications where grounding the exterior parts of a motor may result in greater hazard by
increasing the possibility of a person in the area simultaneously contacting ground and some other nearby
live electrical parts of other ungrounded electrical equipment. In portable equipment it is difficult to be sure
that a positive ground connection is maintained as the equipment is moved, and providing a grounding
conductor may lead to a false sense of security.
Select a VS1CTD cooling tower PM Controller suitable for this motor and its application.
Caution:
Use only a shielded motor power cable with a complete circumferential braided or copper
film/tape ground jacket around the power leads. This ground should be secured to the motor
frame from within the motor terminal box and must return without interruption to the drive ground.
In addition, if the motor and coupled equipment are not on a single common metal base plate, it is
important to equalize the equipment ground potentials by bonding the motor frame to the coupled
equipment using a high frequency conductor such as a braided strap.
Due to the high switching frequencies of inverter controls, the ground connection/path must be low
impedance, not only low resistance. The NEC grounding instructions are intended to protect from low
frequency, high current considerations and are not adequate for grounding of high frequency circuits.
RPM AC cooling tower PM motors are designed to operate with a VS1CTD high frequency PM adjustable
speed drive. To avoid damage to the motor due to bearing currents, the motor must be grounded and
bonded properly. A low impedance ground conductor should be used to ground all RPM AC motors.
Failure to ground the motor properly for high frequency transients (1MHz to 10MHz) may result in electric
discharge damage to the motor bearings.
For the motor power a shielded motor power cable that includes a complete circumferential braided or
copper film/tape ground is recommended. This ground should be secured to the motor frame from within
the motor terminal box and must return without interruption to the drive PE ground connection.
Refer to manual MN776 and quick reference guide MS776.
Condensation Drain
All RPM AC cooling tower motors are provided with a stainless steel T
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DRAIN at the lowest point of the
bottom bracket.
Fan Mounting
RPM AC cooling tower motors are supplied with a shaft suitable for mounting the fan hub directly to the
motor shaft.
The motor must be ordered with the appropriate shaft dimensions to match the fan hub.
This Manual:http://www.manuallib.com/baldor/mn427-inverter-duty-pm-motors-manual.html