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Evaluating Noise in Electric Motors

  • October 2021
  • Number of views: 3723
  • Article rating: 5.0
FREE for Members of EASA
Webinar recording

Determining the source of noise in a motor is often much more challenging than correcting it. However, a methodical approach to investigating the noise can narrow down the possible causes.

Good Practice Guide to Maintain Motor Efficiency

Based on the 2019 and 2003 Rewind Studies of premium efficiency, energy efficient, and IE2 (formerly EF1) motors

  • January 2021
  • Number of views: 8070
  • Article rating: 5.0

Intended primarily for service center personnel, the guide which is now an independent document and not part of the complete EASA/AEMT rewind study report, outlines the good practice repair methods used to achieve the results given in both studies. It contains repair tips, relevant motor terminology, and information about sources of losses in induction motors that affect efficiency.

Vibration and Alignment

  • April 2020
  • Number of views: 5812
  • Article rating: No rating
Webinar recording bundle

A special discounted collection of 9 webinar recordings focusing on a wide variety of vibration, balancing and alignment topics.

Just $45 for EASA members!

Principles of Medium & Large AC Motors, 1st Edition - IEC

  • February 2020
  • Number of views: 28767
  • Article rating: 5.0

This manual covers horizontal and vertical squirrel-cage induction motors in the 300 to 5,000 horsepower range, low- and medium-voltage. Most of the principles covered apply to other sizes as well. This manual focuses primarily on IEC motors and standards.

Auxiliary cooling of electric motors (and other equipment)

  • January 2017
  • Number of views: 4583
  • Article rating: No rating

Although the earliest practical DC motor was built by Moritz Jacobi in 1834, it was over the next 40 years that men like Thomas Davenport, Emil Stohrer and George Westinghouse brought DC machines into industrial use.  It’s inspiring to realize that work-ing DC motors have been around for over 160 years. For the past century, DC machines over 30 or 40 kW have been cooled in the same manner – by mounting a squirrel cage blower directly over the commutator.

Refrigeración auxiliar de motores eléctricos (y otros equipos)

  • January 2017
  • Number of views: 4304
  • Article rating: No rating

Most common methods of balancing overhung rotors

  • July 2015
  • Number of views: 3788
  • Article rating: 5.0

On occasion, service centers are asked to balance fan blades that are designed for an overhung mounting. The fan blade may be received mounted on the shaft, or without any shaft. The decision has to be made about how to mount the rotor in the balancing machine. One solution is to fabricate a mandrel to balance the fan blade between the machine pedestals. The other alternative is to mount the fan blade on the end of the shaft in an overhung configuration, with the fan blade outboard of both balancing machine pedestals. This would be the more expedient method if the fan blade is already mounted on the shaft in the overhung configuration.  How the fan blade is mounted doesn’t change the balance, as long as the fit to the shaft doesn’t change. So the question is, “Which is easiest?” Often it is easiest to mount the rotor in the overhung configuration, but balancing in that configuration presents some challenges. Those challenges are addressed here. 

How to Balance Overhung Fans

  • October 2011
  • Number of views: 4501
  • Article rating: 3.0
Webinar recording

This presentation shows a methodical approach and techniques for tackling this difficult balancing problem.

Fan balancing tips: Understanding basics will improve your skills

  • November 2004
  • Number of views: 2731
  • Article rating: No rating

Most service centers balance rotors routinely, with few surprises in the process. Most of us do not balance fans nearly as often as rotors. The fan balancing tips in this article should be helpful.

Fan law knowledge can help performance

  • October 2002
  • Number of views: 5556
  • Article rating: No rating

Most of us involved in the repair of electrical equipment have a good understanding of how an electric motor works — especially the stator and rotor. But the fan can appear deceptively simple. Fans are pretty interesting, once we learn a few "affinity laws" — rules that also apply to blowers and impellers. This article will review some basic facts about fans that explain how small changes to a fan can make a BIG difference.

Getting The Most From Your Electric Motors

Getting The Most From Your Electric Motors - coverThis 40-page booklet provides great advice for obtaining the longest, most efficient and cost-effective operation from general and definite purpose electric motors.

This booklet covers topics such as:

  • Installation, startup and baseline information
  • Operational monitoring and maintenance
  • Motor and baseline installation data
  • How to read a motor nameplate
  • Motor storage recommendations



EASA/AEMT Rewind Study

EASA Rewind Study cover

The Effect of Repair/Rewinding on Premium Efficiency/IE3 Motors
Tests prove Premium Efficiency/IE3 Motors can be rewound without degrading efficiency.


ANSI/EASA AR100-2020

ANSI/EASA AR100-2015 cover

Recommended Practice for the Repair of Rotating Electrical Apparatus
This is a must-have guide to the repair of rotating electrical machines. Its purpose is to establish recommended practices in each step of the rotating electrical apparatus rewinding and rebuilding processes.



EASA Technical Manual

EASA Technical Manual cover

Revised May 2021
The EASA Technical Manual is the association's definitive and most complete publication. It's available FREE to members in an online format. Members can also download PDFs of the entire manual or individual sections.