Practical tips for running motors with a drive end roller bearing

End users frequently demand that EASA service centers provide an array of test data at the conclusion of the service/repair process. These tests are normally to validate compliance with the customer’s motor repair specifications. It is also a good idea to have your own in-house specifications so you can prove that you’re compliant with EASA motor repair guidelines such as those found in the Recommended Practice for the Repair of Rotating Electrical Apparatus (ANSI/EASA AR100-2006).

One of the more common tests involves running the motor no-load and providing the motor owner with electrical test information and vibration spectrums covering various frequency bands. No-load run tests are commonly applied to AC induction motors. In many cases, these motor types are designed for a belted-duty application. That means they may have a roller bearing in the drive end of the motor.

Special consideration needs to be made so that the roller bearing operating life expectancy is not compromised as a result of run testing the motor without a minimal radial load. On the surface, many customers, and perhaps some motor service centers, think nothing of running a roller bearing motor for as long as it takes to glean test data. Some customers even require minimum run times of an hour or more. In addition, it is not uncommon to find customers applying a belted duty motor with a roller bearing in direct drive applications. If these issues arise, then it is worth a call to the customer to clarify the run test procedures and installation application.This may not sound like a big deal until there is understanding as to what is happening with the roller bearing as it rotates with insufficient radial load.

Editor’s Note: This article is similar to a July 2006 Currents article titled “Tips for Test Running Motors With Roller Bearings.” These two articles complement and supplement each other.