Chuck Yung
EASA Senior Technical Support Specialist

Cuando un cliente llama y quiere reemplazar su motor diesel o de gasolina por un motor eléctrico para impulsar una pieza de maquinaria, es fácil asumir que “los caballos de potencia son caballos de potencia”. ¡No tan rápido! Resulta que existen muchas formas diferentes para medir la potencia. El término caballo de potencia fue adoptado por James Watt a finales de 1700 para comparar la potencia de salida de las máquinas de vapor con la potencia de los caballos de tiro. Aparte de Norte América, la mayor parte del mundo utiliza el vatio para describir la potencia de salida, la cual es la unidad del Sistema Internacional de Unidades (SI). Desde 1700, tenemos hp mecánico, kW, hp métrico, hp eléctrico, hp hidráulico, hp de barra de tracción, hp de frenado, hp de eje e incluso variantes de hp fiscal. Dejando a los gobiernos que quieran sacar partido de ello. 

El propósito de este artículo es aumentar la conciencia sobre la cantidad de factores que se deben considerar al hacer este cambio aparentemente simple.

Matthew Conville, P.E.
EASA Technical Support Specialist

When we consider putting a machine into service, we must consider the duty rating of the machine. If we do not, there is a good chance that the machine being placed into service will have thermal degradation of the windings. Not every application is created equal. For example, a crane motor doesn’t need the same duty rating as a punch press motor that runs continuously, even though they may have the same horsepower ratings. Likewise, a chop saw motor wouldn’t need to have the same duty rating as a pump motor where the pump is operated continuously.

By Mike Howell
EASA Technical Support Specialist

Manufacturers deploy various external connection schemes to produce three-phase induction motors for multiple voltages and/or starting methods. Be sure to follow the relevant connection diagram, which is usually affixed to the motor or contained in its manual. If the diagram is lost, damaged, or ignored, you could find yourself dealing with a costly rewind.

The tips in this article apply to connections commonly encountered on machines with one speed at power frequency. If the external connection information isn’t available, ask your local service center for assistance, especially if several lead tags are missing or there are multiple nameplate speed ratings at power frequency. The service center can also help with unconventional numbering or cross-referencing IEC and NEMA numbering.

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Chuck Yung 
EASA Technical Support Specialist 

If you have ever tried to figure out the field re­sistance from the information on a DC motor nameplate, you probably wonder what in the heck the manufacturer was thinking! You know Ohms Law, but the nameplate information just doesn’t seem to follow it. 

Ohm’s Law: R = E/I 
I = E/R 
RI = E 
Where R = resistance E= voltage I= current

REVISED September 2022!

The EASA Technical Manual, containing more than 900 pages of information specific to electric motor service centers, is available FREE to EASA members as downloadable PDFs of the entire manual or individual sections. The printed version is also available for purchase. Each of the 13 sections features a detailed table of contents.

VIEW, DOWNLOAD OR PURCHASE

Kent Henry 
EASA Technical Support Specialist 

When taking winding data, equal­izer connections can be mistaken for wye points. You may wonder what purpose equalizer connections serve and whether they can just be elimi­nated to simplify the repair process. Before discussing equalizers, we will explore the factors that lead to a need for equalizers. 

A magnetic unbalance within a motor or generator can be a very seri­ous problem. The magnetic balance Stator relies on a marriage of electrical and mechanical elements. When either of these electro-mechani­cal elements changes, it may create a magnetic unbalance. 

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

By Mike Howell
EASA Technical Support Specialist

Too often, replacement specifications for three-phase squirrel-cage induction motors cover only basic nameplate data such as power, speed, voltage, and frame size, while overlooking other important performance characteristics such as the design letter. This can lead to misapplication of a motor, causing poor performance, inoperability, or failures that result in unnecessary downtime. To avoid these problems, familiarize yourself with the following speed-torque characteristics and typical applications for design letters that NEMA and IEC commonly use for small and medium machines (up to about several hundred kilowatts/horsepower).

• NEMA Designs A and B, IEC Design N
• NEMA Design C, IEC Design H
• NEMA Design D

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This EASA software is a valuable interactive training tool ideal for training your novice(s). Even experienced winders will learn from it. The CD teaches how to wind in a richly detailed, step-by-step approach. It includes narrative, animations and video clips, with tests to assess student comprehension. The training, which is divided into 13 lessons, covers data taking, core testing, coil cutoff, burnout, stripping, core preparation, coil making, stator insulation, coil insertion, internal connections, lacing and bracing, inspection and test of untreated and treated windings, and winding treatment. Features include "Pro Tips" and "Drill Downs" that enhance the learning experience and assure that even the most experienced technician will learn from this product. The course is delivered as an interactive Adobe PDF file containing text, audio, video, supporting documents and quizzes.

LEARN MORE

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

Steps to determine characteristics needed for finding a replacement A motor is received from a customer with the request that it be replaced. However, it does not have a nameplate. The steps to determine the motor characteristics needed for identifying a replacement will be described here. These same steps can also be used in the case of repair of a motor without a nameplate, so that a new nameplate with key identification characteristics can be made and attached to the repaired motor. The focus of this article will be NEMA or IEC horizontal motors in standard frame sizes.

Chuck Yung 
EASA Technical Support Specialist

One frequent request of EASA’s technical support staff is for help in identifying unmarked motor leads. This article introduces a set of proce­dures for identifying unmarked leads of 6-lead motors with 1 or 2 wind­ings. For most connections, the only tools required for these procedures are an ohmmeter and surge tester. 

An additional benefit is that these procedures can be used to identify the type of connection (Table 1); for example, when a motor is received without a nameplate. With 6 leads, the motor connection could be part-winding start, wye-delta, or a 2-speed design. 

Jim Bryan
EASA Technical Support Specialist (retired)

La placa de datos de un motor eléctrico revela mucha información valiosa acerca de la capacidad y desempeño de la máquina. Las normas NEMA MG1-2014 (National Electrical Manufacturers Association Motors and Generators 1) e IEC 60034-8 (International Electrotechnical Commission) brindan información que se debe incluir en la placa de datos para cumplir con las normas.

Tom Bishop, P.E. 
EASA Technical Support Specialist 

Motors built to National Electrical Manufacturers Association (NEMA) standards use alphabetical letter codes on the nameplate to designate a number of alternating current (AC) motor characteristics. These characteristics are the code, design, and insulation class.

Read the nameplate carefully as these designations are easily mis­interpreted. Similarly, re-confirm these data items when your customer provides them. For example, the letter “B” could designate a design code, insulation class or kVA code (though highly improbable.) What do these different designations mean? 

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

Correct interpretation of five operating parameters for NEMA, IEC induction motors When someone reads an electric motor nameplate, the normal assumption is that the information can be used at face value. That applies to some but not all of the nameplate information. For example, the power rating (hp or kW) and frame size are specific to the motor. However, ratings such as voltage, frequency, current, speed (rpm) and efficiency have tolerances associated with them. Our focus in this article will be to discuss the correct interpretation of each of these five operating parameters for induction motors of both NEMA and IEC design. Topics discussed include: Voltage and frequency - NEMA MG1-12.44 and IEC 60034-1.7.3 Current - NEMA MG1-12.47 and IEC 60034-1 Speed (rpm) - NEMA MG1-12.46 and IEC 60034-1-12.1 Efficiency - NEMA MG1-12.58 and IEC 60034-1 Note: The letter codes for insulation class, design and kVA code that appear on NEMA motor nameplates are addressed in "Motor Nameplate Letter Code Designations" in the March 2009 issue of Currents.

Jim Bryan
EASA Technical Support Specialist (retired)

The nameplate of an electric motor reveals much valuable information about the capability and performance of the machine. NEMA MG1-2014 (National Electrical Manufacturers Association Motors and Generators 1) and IEC 60034-8 (International Electrotechnical Commission) provide information required to be included on the plate to conform to the standards. 

This varies by the type and size of the motor. For instance, rated field and armature voltages are required for direct current (DC) motors but obviously are not required for alternating current (AC) motors. A table is included that lists the basic requirements applicable to motors. Not all motors will comply with these requirements. These include motors built before the implementation of the standards or outside the jurisdiction of the standards agencies.  Some motors, such as synchronous and wound rotor motors, will have additional requirements. To cover all these is beyond the scope of this article.

Topics covered include:

• Identification
• Power
• Maximum ambient
• Speed
• Phase and voltage
• Code letter
• Design letter
• Efficiency and service factor
• DC motors
• Power factor
• Altitude

By Mike Howell
EASA Senior Technical Support Specialist

Process downtime is expensive—even more so when it’s unexpected. So, when an electric motor fails, we tend to pull, repair, or replace it, and move on as quickly as possible. In doing so, however, we may miss an opportunity to capture basic information that could help improve the reliability of the application. With a little planning, these data can be gathered with no delay in startup.

Topics covered include:

• Collect initial data
• Don't destroy two motors
• Help your service center

READ THE FULL ARTICLE

Las versiones impresas y en forma de descarga del valioso manual didáctico / recurso de EASA, “Principios de Motores C.A. Medianos y Grandes”, se encuentran ahora disponibles en inglés y en español. El manual incluye gráficos e ilustraciones, fotografías y mucha información técnica sobre máquinas C.A., incluyendo como funcionan, información específica sobre los tipos de encerramientos, fabricación de componentes y aplicaciones.  Muchos de los principios incluidos en el libro aplican a todos los motores C.A., especialmente a aquellos accesorios que fueron asociados en el pasado con las máquinas más grandes (como encoders, RTDs, termostatos, calentadores de espacio, sensores de vibración, etc.).

Las versiones  forma de descarga ofrecen funciones prácticas ya que contienen toda la información que contiene el manual impreso, pero en formato PDF, fácil de usa, ya que contiene marcadores que permiten a los lectores navegar rápidamente por el documento y “saltar” a la página deseada.

Las secciones del manual incluyen:

• Terminología y Definiciones del Motor
• Tipos de Encerramientos de Motores
• Aplicaciones Típicas para Motores
• Consideraciones de Manejo y Seguridad
• Teoría Básica del Motor
• Normas para Motores
• Estatores
• Rotores de Jaula de Ardilla
• Ejes
• Lubricación y Rodamientos
• Accesorios del motor & Cajas de Conexiones
• Procedimientos de Inspección y Prueba
• Alineamiento del Motor, Vibración y Ruido
• Procedimientos de Almacenamiento
• Máquinas Sincrónicas

COMPRAR

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 valuable instructional/resource manual is available in printed, downloadable and CD-ROM versions.

For this second edition, this 320-page manual has been reorganized, updated with new information, including revised standards and published articles, and edited extensively. The manual includes drawings, photos and extensive text and documentation on AC motors, including how they work, specific information on enclosures, construction of components and applications. Many of the principles included apply to all AC motors, especially those with accessories that were associated with larger machines in the past (such as encoders, RTDs, thermostats, space heaters, vibration sensors, etc.).

While the 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 NEMA motors.

Sections in the manual include:

• 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 NOW

BOOK DOWNLOAD CD-ROM BOOK & CD-ROM

This book is also available focusing on IEC Standards ... IEC VERSION

Chuck Yung
EASA Senior Technical Support Specialist

When a customer calls and wants to replace his diesel or gasoline engine with an electric motor to drive a piece of machinery, it’s easy to assume that “horsepower is horsepower.” Not so fast! It turns out that there are many different ways to measure power. The term horsepower was adopted by James Watt in the late 1700s to compare the output of steam engines to draft horses. Aside from North America, most of the world uses the International System of Units (SI) unit watt to describe power output. Since the 1700s, we have mechanical hp, kW, metric hp, electric hp, hydraulic hp, drawbar hp, brake hp, shaft hp and even variants of taxable hp. Leave it to governments to want a piece of the action.

The purpose of this article is to increase awareness about the many factors which must be considered when making such a seemingly simple substitution.

This presentation stresses the importance of taking accurate winding data and explains and emphasizes the consequences of inaccurate data. Details are provided on how to take accurate electrical and mechanical data as well as how to verify the data is correct. It gives you and improved ability to "get it right the first time" so as to avoid the added cost and time of another rewind to correct errors.

Matthew Conville, P.E.
Especialista de Soporte Técnico de EASA

Cuando consideremos la puesta en servicio de una máquina, debemos tener en cuenta su tipo de servicio. Si no lo hacemos, es muy probable que la máquina sufra una degradación térmica de los devanados. Sin embargo, no todas las aplicaciones son iguales. Por ejemplo, un motor de una grúa no necesita el mismo tipo de servicio que el de una punzonadora que trabaja de forma continua, a pesar de que pueden tener la misma potencia. Igualmente, un motor de una sierra no necesitaría tener el mismo tipo de servicio que el de una bomba donde la bomba trabaja de forma continua.

By Jim Bryan
EASA Technical Support Specialist (retired)

Whether you're selecting a motor for a new application or a replacement for one that has failed, you need a reliable way to match the capabilities and performance characteristics of various motors with the requirements of the application.

Fortunately, motors that conform with NEMA Std. MG 1-2016 or IEC Std. 60034-8:2007 must include all nameplate data that the respective standards require. What this entails will vary with motor type and size, so for example, rated field and armature current data would be required for direct current (dc) motors but not for alternating current (ac) motors. The focus here is on how the required nameplate data for NEMA and IEC motors can be helpful for selecting the right motor for an application.

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Customers often send in a motor with no nameplate and having little knowledge of the machine’s ratings. This presentation guides the attendees through the process of evaluating the machine using core size, winding data and diagnostic testing to assign reasonable ratings.

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

Mike Howell
EASA Technical Support Specialist

Customers sometimes send in a motor with no nameplate, or an illegible nameplate, having little knowledge of the machine’s ratings. This article will explore the process of evaluating the machine using frame size, winding data and test data to assign reasonable ratings. The general approach will be for typical NEMA or IEC foot-mounted, three-phase AC machines but could be applied to others.