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Articles in Industry Publications

Natural Frequency Testing – Bump Tests and Modal Analysis

  • October 2020
  • Number of views: 13872
FREE for Members of EASA
Webinar recording

Anyone dealing with installed machinery, or even test running motors in the service center, will encounter instances where structural resonance is amplifying machine vibration. The machine may meet stringent specifications in one instance but exceed acceptable vibration levels in another. A good understanding of natural frequencies and the tests necessary to identify them will help solve these vexing situations.

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

  • February 2020
  • Number of views: 53428

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.

Converting motors from horizontal mount to vertical mount

Examine mechanical factors that should be considered when applying a horizontal ball-bearing motor in a vertical mounting position

  • October 2019
  • Number of views: 8825
Trade press article — Plant Services

Occasionally an end user wants to take a motor designed for horizontal mounting and use it in a vertical position. This article addresses some of the key mechanical factors that should be considered when applying a horizontal ball-bearing motor in a vertical mounting position.

Solve vertical pump motor vibration

Knowledge of common vibratory forces helps diagnose and correct problems

  • February 2017
  • Number of views: 13963
Trade press article — Processing Magazine

High vibration is a common problem for motors that are installed on top of vertical pumps. Its source can be a mechanical issue with the pump, motor or coupling or even hydraulic forces from the pump.

Vibration Analysis for Service Centers

  • June 2016
  • Number of views: 7310

This 48-page manual was developed following EASA’s 12-part Vibration for Service Centers webinar series. It serves as an introductory training resource for service center technicians and supervisors involved in measuring, evaluating, and correcting vibration and balancing issues on machines under repair – as opposed to the in-plant predictive maintenance tasks covered in most general classes on the subject.


Achieving proper alignment by detecting and correcting soft foot

  • May 2016
  • Number of views: 10532

Proper alignment of direct-coupled machinery is an essential element in reliability of a new or repaired machine (motor, pump, gear case, etc.). One common impediment to achieving proper alignment and smooth operation is a “soft foot” condition. This article looks at detecting soft foot, correcting soft foot and general recommendations for shims.

Logrando una alineación adecuada detectando y corrigiendo el pie suave

  • May 2016
  • Number of views: 11427

Realizar una correcta alineación de las máquinas acopladas de forma directa es un elemento esencial para garantizar la confiabilidad de operación de una máquina nueva o reparada (motor, bomba, caja de engranajes, etc.). Uno de los impedimentos comunes para lograr una alineación adecuada y un correcto funcionamiento, es el denominado  "pie suave".

Shaft Alignment

  • March 2016
  • Number of views: 7478
Webinar recording

This webinar recording provies a straightforward look at the simple relationship between shaft centerlines that is known as shaft alignment.


Getting The Most From Your Electric Motors

  • February 2016
  • Number of views: 27844

This 40-page booklet provides a great marketing tool for your service center! Use it to provide end users with information that will help them obtain the longest, most efficient and cost-effective operation from general and definite purpose electric motors.


Obteniendo Lo Máximo De Su Motor Eléctrico

  • February 2016
  • Number of views: 14852

​Este folleto de 40 páginas ofrece una gran herramienta de marketing para su centro de servicio! Lo utilizan para proporcionar a los usuarios finales con información que le ayudará a obtener la, operación más eficiente y rentable de propósito más larga de los motores eléctricos generales y definidas.

External mechanical tolerances for electric motors and generators

  • August 2014
  • Number of views: 6651

Service centers routinely check the shaft extension runout of motors and generators. When there are issues associated with them, or when applicable, the coplanarity of the mounting feet and the amount of end foat of horizontal sleeve bearing motors and generators are checked.

Vibration of Belt Driven Machines

  • June 2013
  • Number of views: 6852
Webinar recording

This presentation focuses on:

  • Identifying belt vibrartion
  • Identifying pulley pitch line run-out vibration
  • Other vibration sources
  • ODS analysis

Basics of Machinery Foundations and Bases

  • November 2012
  • Number of views: 4119
Webinar recording

This presentation explains the fundamentals of machinery foundation construction.


The FFT (aka Spectrum): What It Is and Ways to Use It

  • July 2012
  • Number of views: 3736
Webinar recording

This presentation examines:

  • How the spectrum is generated from the vibration signal
  • The effect of f-max ad resolution settings
  • Averaging techniques
  • Scaling and demodulation

Base support and alignment: How understanding construction of the frame can help minimize motor vibration

  • February 2008
  • Number of views: 4924

When vibration problems occur, the magnitude and direction of the vibration can give a good indication of where to look for the cause. When vibration is higher in the vertical plane, one of the first things we should examine is the base/foundation of the motor. If the high vertical readings are compounded by indications of an eccentric airgap, such as high axial vibration and a predominant twice-line-frequency vibration, a "soft foot" or twisted frame is often to blame.

Motor and drive system resonance problems and solutions

  • March 2007
  • Number of views: 5482

Mechanical resonance can be defined as the amplification of the vibration level of a mass or structure at its natural frequency, caused by excitation from an external source. For a rotating mass, this amplification occurs at the critical speed(s). Electrical resonance causes an amplification of the magnitude of voltage or current, or both. The increase in amplitude, whether mechanical or electrical, increases the stress on motor components and negatively affects operation, e.g., increased vibration, instability, increased energy consumption, and premature failure. By receiving energy from an external source, the resonant condition can cause the magnitude of the disturbance to continue to increase until a fault occurs. Mechanical resonance can lead to breakage of motor and drive components, and electrical resonance can result in winding failure. In this article we will discuss mechanical and electrical resonance associated with motors and drives, and provide some solutions to address them.

Assessing soleplate condition and restoration

  • December 2006
  • Number of views: 3054

We'll begin by clarifying what is meant by a "soleplate." In this article, the soleplate is the steel plate or baseplate on which an electric motor or similar rotating machine is mounted. In addition to issues related to soleplate condition assessment and restoration, the article will also cover other areas related to the concrete foundation upon which the machine and soleplate are mounted.

Tips for proper baseplate construction

  • April 2001
  • Number of views: 3056

While the majority of EASAns don't get involved with field construction of motor bases, most do have an important motor base in the service center. The baseplate used in conjunction with the test panel is important, especially when measuring vibration levels of a running motor. This article reviews a few basic steps to make sure that the baseplate functions correctly.