REYMSA COOLING TOWERS, INC.
www.reymsa.com
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▪ Motor must be grounded to common earth ground with drive according to applicable
standards.
▪ Rings should not operate over a keyway because the edges are very sharp.
CAUTION
▪ Care should be taken when handling the ring to prevent fiber damage during
installation.
▪ Do not use thread lock to secure the mounting screws as it may compromise the
conductive path to ground.
CAUTION
A.10.5 MOTOR SHAFT GROUNDING RING
Bearing-related problems are among the most common causes of motor failures. The VFD induced shaft
voltages are capacitively coupled from stator to rotor through parasitic capacitance and create the
possibility of bearing currents.
This problem can be solved grounding the motor shaft with the Shaft Grounding Ring (optional accessory,
see figure A-114) to provide a path of least resistance to ground and divert current away from the motor’s
bearings.
The Motor Shaft Grounding Ring conducts harmful shaft voltages away from the bearings to ground. Voltage
travels from the shaft, through the conductive microfibers, through the housing of the ring, through the
hardware used to attach the ring to the motor, to ground (see figure A-115).
Figure A-114: Motor Shaft Grounding Ring
Figure A-115: Motor Shaft Grounding Ring Path to Ground
Installation
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