Gene Vogel
EASA Pump & Vibration Specialist

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. 

A soft foot occurs when all the feet of a machine case do not sit flat on the supporting base so that tightening the foot bolts causes distortion of the ma­chine case. The source of the soft foot could be a baseplate which is not flat or machine feet which are distorted. Not only does this make it difficult to align the machine, but the casing distortion may add additional load to the bearings and create internal mis­alignment between the rotating and stationary elements of the machine resulting in poor performance and increased vibration.

Tom Bishop, P.E. 
EASA Technical Support Specialist 

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.

Chuck Yung 
EASA Technical Support Specialist 

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. 

Construction basics 
It is common practice for the align­ment technician to use prefabricated shims under the feet, sized to accept the hold-down bolt. The person perform­ing the alignment may not realize that a motor frame is not as solid as it appears. The fact that the foot itself might be over an inch (25 mm) thick, and the frame is cast iron or steel, causes the person to assume that it cannot distort. Nothing could be further from the truth. Because of that assumption, shims are often not placed to the greatest benefit. By understanding some construction basics, we can better place the shims to obtain the lowest vibration readings. 

A faulty machine foundation or base can lead to excessive vibration and premature failure. This presentation explains the fundamentals of machinery foundation construction and how to identify and troubleshoot machine base problems, including basic vibration techniques and ODS analysis.

Tom Bishop, P.E.
EASA Senior Technical Support Specialist

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.

These key factors include:

• Axial thrust load capacity of bearing supporting rotor weight
• Rotor weight
• Weight of output shaft attachments
• Axial thrust from direct-connected driven equipment\
• Bearing lubrication paths
• Bearing lubricant retention
• Shaft up or shaft down orientation
• Ingress protection
• Locking axial thrust bearing

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Tom Bishop, P.E.
EASA Senior Technical Support Specialist

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. A common point about all three of these dimensions is that they are checked with the machine assembled; that is, no disassembly is required. There are many other mechanical tolerances associated with motors and generators, such as bearing fits. However, the focus of this article will be the three tolerances just mentioned. Rather than referring to both electric motors and generators, for brevity the term “machine” will be used.

Topics covered include:

• Shaft extension runout tolerance
• Coplanarity of mounting feet tolerance
• End float

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 with these characteristics:                                                                                                          

• Three-phase, squirrel-cage induction motors manufactured to NEMA MG 1 standards 
• Power ratings from 1 to 500 hp (1 to 375 kW)                                        
• Speeds of 900 to 3600 rpm (8 to 2 poles) 
• Voltages up to 1000V, 50/60 Hz 
• All standard enclosures (i.e., DP, TEFC, WPI, WPII) 
• Rolling element (ball and roller) and sleeve bearings

This booklet covers topics such as:

• Installation, startup and baseline information
  • Basic system considerations
  • Installation
  • Startup procedures
  • Baseline data
  • Total motor management
• Operational monitoring and maintenance
  • Application specific considerations
  • Preventive, predictive and reliability-based maintenance
  • Inspection and testing
  • Relubrication of bearings
• Motor and baseline installation data
• How to read a motor nameplate
  • Overview
  • Required information
  • Other terms
• Motor storage recommendations
  • Motor storage basics
  • Preparation for storage
  • Periodic maintenance

This resource is provided as a FREE download (use the link below). You can also purchase printed copies ready to distribute to your current or potential new customers. The cover of this booklet can also be imprinted with your company's logo and contact information (minimum order or 200). Contact EASA Customer Service for details.

READ MORE ABOUT THE FEATURES AND BENEFITS

Por Gene Vogel
Especialista de Bombas y Vibraciones de EASA

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".

Tom Bishop, P.E. 
EASA Technical Support Specialist 

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. 

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.

This presentation covers:

• What is a natural frequency and why do they exist
• How to conduct a basic bump test with a single channel analyzer
• What is a modal analysis and what additional information does it provide
• Related tests and concerns

This webinar is useful for service center technicians, supervisors and managers.

​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 con estas características:

• Trifásica, motores de inducción de jaula de ardilla fabricados con las normas NEMA MG 1
• Los valores de potencia de 1 a 500 CV (1 - 375 kW)
• Velocidades de 900 a 3600 rpm (8 a 2 polos)
• Tensiones de hasta 1000 V, 50/60 Hz
• Todas las cajas estándar (es decir, DP, TEFC, WPI, WPII)
• Rodando elemento (bolas y ruedas) y los cojinetes de manguito

Este folleto cubre temas tales como:

• Instalación, puesta en marcha y la información de base
• monitoreo y mantenimiento operativo
• Datos del motor y la instalación de línea de base
• Cómo leer una placa de identificación del motor
• recomendaciones de almacenamiento del motor

Este recurso se ofrece como una descarga gratuita (utilizar el enlace más abajo). También puede comprar copias impresas listo para distribuir a sus actuales o potenciales nuevos clientes. La portada de este folleto también se puede imprimir con el logotipo e información de contacto de su empresa (pedido mínimo o 200). Póngase en contacto con Servicio al Cliente EASA para más detalles.

This version of Principles of Medium & Large AC Motors manual is now available to address applicable IEC standards and practices. This 360-page manual was developed by industry experts in Europe along with EASA's engineering team. (The "original" version of this book based on NEMA standards remains available as a separate document.)

This manual includes drawings, photos and extensive text and documentation on AC motors, including how they work, information on enclosures, construction on components and applications. Many of the principles included apply to all AC motors, especially those with accessories that are associated with larger machines in the past (such as encoders, RTDs, thermostats, space heaters and vibration sensors).

While the manual covers horizontal and vertical squirrel-cage induction motors in the 37 to 3,700 kW (300 to 5,000 hp) range, low- and medium-voltage, most of the principles covered apply to other sizes as well. 

This valuable instructional/resource manual is available in printed and downloadable versions, and focuses primarily on IEC motors.

Sections in the manual include:
(Download the PDF below for the complete Tables of Contents)

• Motor nomenclature & definitions
• Motor enclosures
• Typical motor applications
• Safety & handling considerations
• Basic motor theory
• Motor standards
• Stators
• Squirrel cage rotors
• Shafts
• Bearings & lubrication
• Motor accessories & terminal boxes
• Test & inspection procedures
• Motor alignment, vibration & noise
• Storage procedures
• Synchronous machines

BUY A COPY FOR YOUR OFFICE

PRINTED BOOK DOWNLOADABLE PDF

This book is also available focusing on NEMA Standards — in both English and Español.

NEMA - English NEMA - Español

This webinar recording provies a straightforward look at the simple relationship between shaft centerlines that is known as shaft alignment. Bypassing the common discussion of laser and manual instruments, this presentation gets to the heart of the shaft alignment process. Topics covered will include:

• Fundamental concepts
• How to visualize machine case position
• Practical solutions for moving machine cases
• Applying tolerances
• The foot-base-foundation connection

By Gene Vogel
EASA Pump & Vibration Specialist

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. Structural issues involving “reed frequency” resonance often amplify the problem, but effective diagnosis must begin with an understanding of the underlying vibratory forces. Although the general vertical pump category includes submersibles, this article focuses solely on the ones that most commonly exhibit high-vibration conditions: surface-mounted pumps with the motor bolted to a pedestal on top.

Topics covered in this article include:

• Mass unbalance
• Coupling type and alignment
• Mechanical action of pump shaft & impeller
• Hydraulic action of fluid
• Resonant frequencies
• Basic frequency analysis
• Trim balancing
• Other possibilities
• Vertical pump troubleshooting checklist

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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

Chuck Yung
EASA Senior Technical Support Specialist

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. Vibration levels recorded in the shop should correlate to those taken when the customer installs the motor in the plant. A discrepancy gives valuable clues as to the cause of vibration, allowing quick identification of the problem. For this reason, the design and installation of that baseplate are important if the in-shop vibration readings are to have value. Since that is important, let's review a few basic steps to make sure that the baseplate functions correctly.

Topics covered in this article include:

• Importance of baseplate design and installation
• Maximizing bond area
• Use of anchor bolts

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.

This document is intended as basic introductory training material for anyone who may be involved in evaluating or correcting vibration issues on machines repaired in the service center. Only certain sections may be of interest depending on the area and amount of involvement in vibration issues.

For a technician with responsibility for analyzing and correcting vibration and balancing issues, a general understanding of all of the information is essential. For technicians who will conduct field vibration and balancing services in customers' facilities, additional training is strongly recommended. A Level 1 vibration analysis class (usually 4 or 5 days) is a first step toward the competence needed for conducting field services. A Level 2 class is recommended. A number of providers offer ANSI-certified Level 1 and Level 2 vibration analysis classes, which normally include an opportunity for certification.

Major sections in the document include:

• Introduction and Overview
• Vibration Basics: Amplitude, Frequency and Phase
• Vibration Tolerances
• Basic Vibration Analysis
• Dynamic Balancing Basics
• Resonance
• Rolling Element Bearing Vibration
• Demodulation and High Frequency Band Measurements
• Field Analysis Techniques
• Field Balancing—Problems and Solutions

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This presentation focuses on:

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