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How to schedule

To schedule private education for your group, contact:

Dale Shuter, CMP
Meetings & Expositions Manager

+1 314 993 2220, ext. 3335
dshuter@easa.com

1 hour of training

$300 for EASA Chapters/Regions
$400 for member companies
$800 for non-members

How a webinar works

All EASA private webinars are live events in which the audio and video are streamed to your computer over the Internet. Prior to the program, you will receive a web link to join the meeting. 

The presentation portion of the webinar will last about 45 minutes, followed by about 15 minutes of questions and answers.

Requirements

  • Internet connection
  • Computer with audio input (microphone) and audio output (speakers) appropriate for your size group
  • TV or projector/screen

Zoom logo

The Zoom webinar service EASA uses will ask to install a small plugin. Your computer must be configured to allow this in order to have full functionality. Please check with your IT department or company's security policy prior to scheduling a private webinar.

Private webinars

EASA's private webinars are an inexpensive way to bring an EASA engineer into your service center, place of business or group meeting without incurring travel expenses or lost production time.

2-Speed, 2-Winding Pole Group Connections

2-Speed, 2-Winding Pole Group Connections

The topics covered included in this webinar recording:

  • One circuit wye connection — Best, no parallel paths, turns per coil may prevent this
  • Delta or multiple parallel circuits—Produces closed circuits, Circulating currents
  • Open delta (4 wire connection)
  • Permissible connections—Skip pole, adjacent pole
  • Determined by speed combination

T​arget audience: This webinar recording will benefit service center technicians and supervisors. 

A closer look at winding conversions by reconnection

A closer look at winding conversions by reconnection

When a customer requests a motor be rewound for a new set of conditions, that is typically what we in the service center industry provide them. However, there are occasions where the customer request may be fulfilled by reconnection; in some cases, this is done simply by revising the motor nameplate data. The purpose of this article is to identify and explain some of these scenarios.

Reconnections covered include:

  • Part winding start (PWS)
  • Single voltage 12 leads
  • 2 wye and 1 delta
  • 230/460-575 volts 380 volts 50 Hz and 460 volts 60 Hz
  • 2300 and 4000 volts

For an additional reference, see "Variables to consider when making motor frequency changes between 50, 60 Hz" published November 2008.

AC Motor Redesign

AC Motor Redesign

EASA’s AC Motor Redesign manual explains how to make all possible changes in the ratings of AC electric motors, within design limitations. Besides mathematical formulas, it provides guidelines on the limitations for each type of redesign. These are useful in determining whether a desired new rating is possible before the motor is stripped. Terms are expressed in both English and metric units. Each chapter contains at least one example to guide you through your own redesigns.

This book is available as a FREE download (see link below) or printed copies can be purchased.                                                                                    

Chapters in this book include:

  • Wire size change
  • Voltage change
  • Horsepower or kilowatt change
  • Frequency change
  • Phase change
  • Circuit change
  • Span or chord factor change
  • Winding connection change
  • The master formula
  • Converting concentric windings to lap windings
  • Converting lap windings to concentric windings
  • Notes on pole changing
  • Decreasing speed by increasing poles
  • Increasing speed by decreasing poles
  • Single-speed to two-speed, one winding
  • Single-speed to two-speed, two winding
  • Developing a winding for a bare core
  • Strengthening or weakening a motor - short method
  • Determining the proper connection
  • Single-phase redesign
  • Calculation of secondary voltage
  • Determining three-phase coil grouping 

AC Motor Redesign: Speed Changes

AC Motor Redesign: Speed Changes

Mike Howell
EASA Technical Support Specialist

This technical paper from the 2014 EASA Convention focuses on AC motor redesigns involving speed changes. Service centers encounter scenarios such as the procurement of a single-speed motor that must be redesigned for two speeds or redesign of an existing two-speed motor for use on an adjustable-speed drive. Topics covered include:

  • Single-speed, one-winding to two-speed, one-winding
  • Single-speed, one-winding to two-speed, two-winding
  • Two-speed, two-winding to single-speed, one-winding
  • Two-speed, one-winding to single-speed, one winding

The redesign examples use EASA’s AC Motor Verification & Redesign program, including use of the integrated Motor Winding Database for locating comparative data. Examples include other changes such as voltage, frequency and horsepower.

AC Motor Verification & Redesign - Ver. 4

AC Motor Verification & Redesign - Ver. 4

EASA's AC Motor Verification & Redesign - Ver. 4 software has been further refined and now contains and is fully integrated with EASA's Motor Rewind Database. This makes it the perfect program to lookup motor data, to verify existing winding data, and to perform motor winding redesigns.

This valuable resource is available only to EASA Members.

The AC Motor Verification and Redesign software provides easy verification of either concentric or lap windings, as well as redesigns with changes in poles/speed, horsepower, frequency or voltage. The redesign report with original and new winding data is output as an Adobe Reader (PDF) file and can be printed or saved. The program also allows you to search EASA’s extensive motor winding database. Choose to use the included database containing more than 250,000 windings or connect to the live, ever-expanding online database. Once found, motors from the database can be automatically imported as a starting point for further redesign.

Key software features include:

  • Improved redesign accuracy and database search options.
  • Includes the EASA Motor Rewind Database with more than 250,000 reported AC and DC windings. Use static built-in rewind database, or choose to use the constantly-updated, online database.
  • Allows multiple simultaneous input cases for comparison of different motors.
  • Users can opt to exclude half-wire sizes from automatic calculations.
  • Automatic conversion from AWG to metric wire and square/rectangular wire to round magnet wire.
  • The user can limit redesigns to only those matching in-stock wire sizes.
  • Standard "one line formula calculations" are available from the Reference menu.
  • Help files provide context-sensitive help. Includes the full EASA AC Motor Redesign book. Spanish translation of Help reference materials is provided.
  • Built-in reference tables for chord factor, coil grouping, distribution factors, flux densities, and more.

System requirements

  • Windows® XP, Windows® Vista, Windows® 7, 8 or 10 (Note: To run on a Mac, you must run a supported Windows OS using virtual machine software such as Parallels or Fusion.) 
  • CD-ROM or DVD drive
  • Approximately 1.25 GB free space on hard drive
  • Screen resolution of at least 1280x768 (with text size set at 100%)
  • Java™ Virtual Machine 1.8 or higher (Version 1.8 included on CD-ROM)
  • Adobe® Reader (for report output/printing; free download from https://get.adobe.com/reader/)
  • Internet access for retrieving future software updates and optional online motor rewind database

Avoid costly motor connection mistakes

Avoid costly motor connection mistakes

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.

READ THE FULL ARTICLE

Best AC Rewind Practices

Best AC Rewind Practices

Electrom InstrumentsPresented by Chuck Yung
EASA Senior Technical Support Specialist

This webinar recording shares some of the “best practice” rewind methods used by (and learned from) EASA service centers around the world: connection recognition, best insulating materials, wire choices and tips to save time and effort. Topics covered include:

  • Slot liner, separators and phase insulation
  • Managing voltage stresses
  • Making the connection: solder, crimp fittings or silphos
  • Lacing tips
  • Testing the completed winding

This webinar is intended for experienced and prospective winders, and those who supervise winders.

Beyond I2R – Additional copper losses in stator windings

Beyond I2R – Additional copper losses in stator windings

Mike Howell
EASA Technical Support Specialist

The March 2013 Currents article titled “Stator I2R loss: considerations for rewinds and redesigns” describes the stator I2R loss, its calculation and how to control it during rewinds. This follow up will provide a brief review and then explore the additional stator copper losses mentioned in that article.

Bobinage d'un stator triphasé

Bobinage d'un stator triphasé

Cette formation en ligne a été développée par EASA et a été traduite en français avec la collaboration de EASA, Chapitre Québec et les Maritimes et d’Élexpertise. Cette formation a été réalisée avec l’aide financière de la Commission des partenaires du marché du travail.

L’objectif principal est de permettre à l’apprenant d’inscrire les données sur une fiche technique en faisant référence aux notions de base d’un stator triphasé. Les activités d’apprentissage touchent les principales étapes du bobinage. L’apprenant apprend l’entretien et la réparation d’un stator triphasé selon les normes en vigueur.

Remarque: Cette formation sera accessible en ligne pour une période de 6 mois.

CLIQUEZ ICI POUR VOUS INSCRIRE

Prix membre: $199 US
Prix membre non: $599 US

CONTENU                                                                                          

INTRODUCTION

MODULE 1- Notions de base sur le stator triphasé

  • Structure du stator triphasé
  • Schémas de raccordement du bobinage de stator
  • Utilisation des fiches techniques

MODULE 2 - Entretien et réparation d'un stator triphasé

  • Mesures de sécurité
  • Décapage du bobinage d’un stator triphasé
  • Démoulage du bobinage d’un stator triphasé
  • Préparation du noyau d’un stator triphasé
  • Fabrication des enroulements d’un stator triphasé
  • Insertion des enroulements dans un stator triphasé
  • Raccordement des enroulements et des conducteurs électriques
  • Laçage et renforcement du bobinage d’un stator triphasé
  • Inspection du bobinage avant finition
  • Test du bobinage d’un stator triphasé
  • Finition du bobinage de stator triphasé

CONCLUSION

DURÉE: 10 heures

Circuitos en paralelo: Más de lo que parece

Circuitos en paralelo: Más de lo que parece

By Chuck Yung
EASA Senior Technical Support Specialist

Existen beneficios e inconvenientes al usar circuitos en paralelo en un bobinado trifásico. Sea que estemos hablando de un bobinado de alambre redondo o de pletina (solera), algunas de las consideraciones se comparten. Comencemos con lo básico: Entre más alta la potencia y/o más bajo el voltaje nominal, menos vueltas por bobina se utilizan. Debido a que un devanado trifásico tiene grupos por fase y por polo que alternan ABC, ABC, ABC, etc., los puentes entre grupos podrían ser 1-4, 1-7, 1-10, 1-13, etc., o cualquier combinación de ellos, siempre y cuando se conserve la polaridad alternada de los grupos y que las fases no se crucen entre sí.

Circulating Currents in AC Stator Windings

Circulating Currents in AC Stator Windings

Presented by Chuck Yung
EASA Senior Technical Support Specialist

This webinar recording discusses the equalized connections found in an increasing number of factory windings, explains why they are used, and addresses whether or not they are needed when converting a concentric winding to a lap winding. Alternatives, such as changing the number of circuits, or the special extra-long jumpers, are also compared.

The webinar recording covers

  • Explanation of why machine-wound concentric windings use equalizers
  • Effect of unbalanced voltage
  • Role of air gap in causing circulating currents
  • Labor involved and risk of failures due to increased complexity
  • How to properly locate the equalizers

This webinar is useful for engineers, service center managers, mechanics and sales representatives.

Comparing differences in wye-delta and part-winding-start connections

Comparing differences in wye-delta and part-winding-start connections

Chuck Yung
EASA Technical Support Specialist

One of the most misunderstood winding connections is the part-winding start. Many customers (and some members) tend to blur the differences between the part-winding-start (PWS) connection and wye-start, delta-run connections.

Let’s review the Wye-Delta first before looking more closely at the part-winding-start connection. The wye-start, delta-run connection is designed to reduce starting current, heating of the windings and rotor, and starting torque. It does this by temporarily connecting the motor for a voltage higher than line voltage.

Conexiones Externas en los Motores Eléctricos Trifásicos

Conexiones Externas en los Motores Eléctricos Trifásicos

En Español

Presentado por Carlos Ramirez, EASA Technical Support Specialist

La conexión incorrecta de los motores eléctricos es una causa frecuente de fallo y es más común de lo que parece. La falta de información y la mala interpretación de los datos de placa son algunas de sus causas. En este webinario se explican los diferentes tipos de conexiones para los motores eléctricos trifásicos de una o varias velocidades con al menos 6 cables de salida y se comparan las equivalencias NEMA e IEC para el marcado de cables. La información proporcionada también será de gran utilidad para evitar el conexionado incorrecto en los diferentes voltajes. También incluye las conexiones por devanado partido (Part Winding) y como interpretar la información de la conexión de la placa de datos.

El webinar incluye:

  • Conexiones Estrella y Delta (“Triángulo”)
  • Conexiones para motores de una sola velocidad con al menos 6 cables de salida
  • Conexiones para motores de dos velocidades con al menos 6 cables de salida
  • Conexiones para Devanado Partido (Part winding)
  • Equivalencias NEMA e IEC para el marcado de cables  
  • Interpretación de la información de la conexión de la placa de datos

Este webinario es útil para supervisores, personal encargado de realizar pruebas y responsables del centro de servicio.

Three-Phase Motor External Connections
Misconnection of electric motors is a common cause of failure, and it’s more common than it seems. The lack of information and an incorrect interpretation of the nameplate information are some of its causes. This webinar will explain different connections that can be used in three-phase motors with 6 or more leads single-speed or multi-speed comparing NEMA and IEC labeling methods. Information provided will also be useful for avoiding misconnections at different voltages and includes part winding connections and nameplate information interpretation.

The webinar will include:

  • Wye and delta connections
  • 6 and more leads single-speed connections
  • 6 and more leads two-speed connections
  • Part winding connections
  • NEMA and IEC marking equivalents
  • Nameplate information interpretation
This webinar will be useful for service center managers, supervisors and test technicians.

 

Connections on AC electric motors under 600 volts

Connections on AC electric motors under 600 volts

Anthony Sieracki
Spina Electric Co.

In all aspects of electric motor repair specifications and instructions, we should refer to industry standards, government standards, electrical codes, manufacturing recommendations and of course EASA's Recommended Practice for the Repair of Rotating Electrical Apparatus (ANSI/EASA AR100-2010). All are written to help us perform and accomplish the best repairs possible. This article covers a topic that is often times taken for granted, yet it is key to making sure your repaired motor does not fail prematurely. We will cover the proper methods for making connections on AC electric motors under 600 volts. The most common methods are crimped terminals, multiple bolt connector points and split bolts connectors.

Consideraciones para convertir bobinados de alambre redondo a pletina (solera)

Consideraciones para convertir bobinados de alambre redondo a pletina (solera)

Chuck Yung
Especialista Sénior de Soporte Técnico de EASA

Con el aumento continuo de los tamaños de los motores CA y la obvia superioridad de los devanados con bobinas preformadas (pletina o solera), un área en la que podemos ayudar a mejorar la confiabilidad de los motores de nuestros clientes es rediseñando estos motores grandes de alambre redondo para que acepten bobinas preformadas. La mayoría de los reparadores estarían de acuerdo en que las máquinas de alambre redondo por arriba de 600 hp (450 kW) deberían rediseñarse con bobinas preformadas. Así mismo, aquellas con tensiones nominales superiores a 2 kV serían más confiables con bobinas de pletina.

Nadie quiere rebobinar un motor con 60 #14 AWG (62- 1.6 mm). Con la abundancia de proveedores especializados en laminaciones de estatores, el costo y la practicidad para convertir motores de alambre redondo a pletina está al alcance de casi todos los centros de servicio. Las laminaciones para reemplazar el núcleo pueden ser troqueladas o cortadas con láser o agua y entregadas en tiempos muy razonables.

Considerations for random to form winding conversions

Considerations for random to form winding conversions

Chuck Yung
EASA Senior Technical Support Specialist

With a steady increase in random wound AC motor sizes and the obvious superiority of the form coil winding, one area where we can help improve customers' motor reliability is by redesigning those large random wound motors to accept form coils. Most repairers would agree that machines rated larger than 600 hp (450 kW) should be designed as form coil machines. Likewise, those rated over 2 kV will be much more reliable as form coil machines.

No one wants to rewind a motor using 60 #14 AWG (62- 1.6 mm) wires in hand. With an abundance of niche suppliers of stator laminations, the cost and practicality of converting a random wound motor to form coil are available to nearly all service centers. Replacement laminations can be punched, laser-cut or water-cut, and supplied with very reasonable delivery times.

Continuación de las pérdidas I2R – pérdidas adicionales en los bobinados del estator

Continuación de las pérdidas I2R – pérdidas adicionales en los bobinados del estator

Mike Howell
Especialista de Soporte Técnico de EASA

El artículo publicado en marzo del 2013 en la revista Currents de EASA titulado “Stator I2R loss: considerations for rewinds and redesigns” describe las pérdidas I2R del estator, su cálculo y cómo controlarlas durante el rebobinado. Esta continuación, proporcionará una breve revisión y luego explorará las pérdidas adicionales en el cobre del estator mencionadas en ese artículo.

 

Dual voltage: Twice as much to go wrong?

Dual voltage: Twice as much to go wrong?

Dealing with voltage ratios and wye/delta connections

Chuck Yung 
EASA Technical Support Specialist 

In the world of three-phase electric motors, one area which seems to cause great confusion is the use of electric motors which are rated for more than one voltage. Especially today, with so much international commerce, it is understandable that different meanings might be assumed for this simple term. 

Those readers in the U.S. are ac­customed to “dual-voltage” 230/460v ratings. The 1:2 ratio lends itself to 9-lead windings, with connection combinations such as 1- and 2-circuit wye, 2 and 4-delta, 3 and 6-wye, etc. The common factor is that the circuits and the possible operating voltages have the same 1:2 ratio.

Equalizer connections and taking winding data

Equalizer connections and taking winding data

Understanding the relationship between electrical, mechanical elements

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. 

Familiarizandose con los bobinados fraccionarios concentrados-FSCW

Familiarizandose con los bobinados fraccionarios concentrados-FSCW

Mike Howell
EASA Technical Support Specialist

Los bobinados fraccionarios concentrados, en inglés Fractional-Slot Concentrated Windings (FSCW), han sido empleados durante décadas, principalmente en máquinas pequeñas. Sin embargo, el avance continuo en la electrónica de potencia junto con la necesidad de tener máquinas más eficientes y con mayor densidad de potencia está aumentando el uso de este tipo de bobinados en máquinas de diferentes tipos y tamaños.

Funcionamiento de un motor trifásico con energía monofásica

Funcionamiento de un motor trifásico con energía monofásica

Chuck Yung
Especialista Sénior de Soporte Técnico de EASA 

Todos nosotros tenemos ese cliente ocasional que compró “una ganga” en una subasta, como un compresor, un torno o una máquina para trabajar madera y que solo descubre al comenzar a instalarlo que ese equipo tenía un motor trifásico y que él dispone únicamente de energía monofásica. Posiblemente sea su vecino o un amigo de la iglesia. En cualquier caso, usted está a punto de ser contactado para “convertir” esa parte del equipo y probablemente piensa que eso le va a costar más de lo que el puede gastar.

Getting to know fractional-slot concentrated windings (FSCW)

Getting to know fractional-slot concentrated windings (FSCW)

Mike Howell
EASA Technical Support Specialist

Fractional-slot concentrated windings (FSCW) have been used for decades, primarily in small machines. But continued technological advancement in power electronics along with the need for more efficient and power-dense machines is increasing use of FSCW in a variety of machine types and sizes.

How to avoid circulating currents in multi-speed, two-winding machines

How to avoid circulating currents in multi-speed, two-winding machines

Cyndi Nyberg 
Former EASA Technical Support Specialist 

“I have rewound a two-speed, two-winding motor. The high speed runs fine — the no-load current seems right. But when I test the low speed, the amps are far too high at rated voltage. It draws significantly above the rated current, at no-load! I know that the winding data is correct. What could be wrong?” 

This is one of the most common problems we encounter at the EASA office.  The solution is almost always the same. There are three questions we ask in return.

  1. What are the two speeds?
  2. What are the number of circuits in each winding?
  3. What jumpers are used to connect each winding? 

How To Wind Three-Phase Stators (Version 2)

How To Wind Three-Phase Stators (Version 2)

Self-paced, interactive training for stators 600 volts or less

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

How Winding Changes Affect Motor Performance

How Winding Changes Affect Motor Performance

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

This webinar recording focuses on the effect of three-phase stator winding changes on efficiency and reliability.

Specific changes addressed will include:

  • Connection
  • Circuits
  • Turns
  • Span/pitch
  • Grouping sequence
  • Concentric to lap, and vice versa
  • Wire area per turn and per slot

Target audience: Service center technicians and supervisors.

Identificando los cables no marcados en motoresde 6 cables con 1 ó 2 bobinados

Identificando los cables no marcados en motoresde 6 cables con 1 ó 2 bobinados

Chuck Yung
Especialista Senior de Soporte Técnico de EASA

Un requerimiento frecuente al personal de soporte técnico de EASA es la solicitud de ayuda para la identificación de los cables de salida que no están marcados. Este artículo establece una serie de procedimientos para identificar los cables no marcados en motores con 1 ó 2 bobinados que tienen 6 cables de salida. Para identificar la mayoría de las conexiones, los únicos instrumentos necesarios son un óhmetro y un equipo de onda de choque. (surge tester)

Identifying unmarked leads of 6-lead motors with 1 or 2 windings

Identifying unmarked leads of 6-lead motors with 1 or 2 windings

Procedures also help identify type of connection when there is no nameplate

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. 

Important questions to ask when your customer orders a 12-lead motor

Important questions to ask when your customer orders a 12-lead motor

Chuck Yung 
EASA Technical Support Specialist 

When a customer calls and orders a motor, he usually specifies only the Hp/kW rating, rpm, frame, enclosure and voltage rating. That leaves at least one critical area where the elec­trician can go wrong: The starting method and number of leads. 

Induction Motor Rotor Windings: Squirrel-Cage and Wound Rotor Basics for the Technician

Induction Motor Rotor Windings: Squirrel-Cage and Wound Rotor Basics for the Technician

This presentation covers the following topics:

  • Induction motor basics for operation
  • Squirrel-cage
    • Conductor material
    • Deep-bar effect
    • Multiple-cage windings
    • Phase resistance
    • IEC/NEMA design letters
    • Speed-torque characteristics
  • Wound-rotor
    • Winding construction
    • Wave-wound connections
    • Distribution factor and chord factor
    • Rotor phase voltage
    • Speed-torque characteristics

Target audience: This webinar will benefit service center technicians and supervisors. 

Información necesaria para completar la solicitud de verificación de datos & rediseño

Información necesaria para completar la solicitud de verificación de datos & rediseño

Jim Bryan
EASA Technical Support Specialist (retired)

En la edición de Febrero de nuestra revista Currents, Mike Parsons proporcionó excelentes consejos para contactar y formular preguntas al Departamento de Soporte Técnico de EASA. Mike hace parte de Hupp Electric Motors Co. en Marion, Iowa y es miembro del Comité de Educación Técnica y me gustaría resaltar una declaración que hizo: “¡Ustedes no son ninguna molestia!” De hecho, son nuestro sustento. 

Durante años, sus Juntas Directivas y Gerentes han asignado recursos para aumentar el número de especialistas de soporte técnico y en encuestas anteriores de evaluación de necesidades, los miembros han calificado al soporte técnico/ingeniería de EASA como el beneficio número uno de la membresía. Así que aprovechad esto por todos los medios. 

Para ayudarle a obtener el mayor beneficio, este artículo explicará la información requerida para llenar la Solicitud de Verificación de Datos & Rediseño. Puede completar y enviar su solicitud en línea en www. easa.com/resources/tech_support/ redesign_inquiry o descargarla en este link y enviarla por fax o correo electrónico. Ver Figura 1. En el caso que llene la solicitud a mano, asegúrese de escribir claramente. Por ejemplo, los números “1” o “7”, o “5” o “6”, se parecen cuando se escriben muy rápido.

Figura 1

Cuando esté llenando la solicitud impresa o en línea, verá que ciertos campos están marcados con un asterisco (*), esto implica que son obligatorios para poder completar la solicitud. Algunas veces toda esta información no está disponible por lo que se debe informar de esto en el campo apropiado. Entonces nosotros haremos lo posible para determinar lo que se debe hacer. 

Comenzando con la información de la empresa, los datos importantes son su número de identificación de EASA, su nombre y la información de contacto por si nos surgen algunas preguntas. Indique porque medio prefiere recibir su respuesta, proporcionando un número de fax, un correo electrónico o su número telefónico. Nosotros utilizamos los datos de placa y la información del fabricante para ingresarla en la base de datos de EASA. Aunque esta información será de ayuda para futuras consultas, en caso que falte, no impedirá que la solicitud sea procesada. 

Datos de placa 

*Hp o kW es la potencia de la placa de datos que determina la capacidad de carga de la máquina. Cuando existen opciones como esta, se debe encerrar dentro de un círculo la unidad correcta. Las rpm o el número de polos y la frecuencia determinan la velocidad de la máquina. La frecuencia, el voltaje y los amperios también son tomados de la placa de datos. Si existe más de un valor todos deberán ser reportados.

Datos y dimensiones del núcleo 

Uno de los puntos clave para evaluar o rediseñar un bobinado es verificar si las densidades de flujo magnético en el entre hierro y en el núcleo del estator son razonables. Estas se pueden expresar en miles de líneas de flujo por pulgada cuadrada (klíneas/ pul²) o Teslas (T) y se comparan con los valores máximos establecidos en el entre hierro (65 klíneas/pul² o 1 T), yugo (130 klíneas/pul² o 2 T) y diente (130 klíneas/pul² o 2 T). También son comparadas con motores de la base de datos de EASA con dimensiones y potencias similares. Podemos calcular el número de líneas de flujo por pulgada cuadrada utilizando el voltaje, la frecuencia, los datos del bobinado y las dimensiones del núcleo. Los cálculos requieren mediciones precisas de cada uno de los componentes así como también el número de ranuras del estator. La Figura 2 proporciona las directrices para tomar estas medidas.

Figura 2

El número de ranuras del rotor es opcional a no ser que se requiera un cambio de velocidad. Dependiendo del número de polos, ciertas combinaciones de ranuras rotor-estator producirán ruido, variación del torque a muy baja velocidad (cogging) o una reducción del torque cuando el motor comienza acelerar (cusp). Con el número de barras del rotor podemos verificar si esta combinación ocasionará problemas en su motor. Tenga en cuenta que si las ranuras del estator o del rotor son inclinadas, dicha combinación no deberá causar estos problemas. 

El largo del núcleo deberá ser la distancia total entre los dos extremos del núcleo. Si existen ductos de aire, el número y ancho de los mismos se deberán anotar en los campos provistos. Estos datos serán incluidos posteriormente en la evaluación. 

En los bobinados preformados (pletina) son necesarias las dimensiones de la ranura del estator. Las medidas exactas facilitarán el cálculo de los calibres o tamaños de alambre y del aislamiento, para que se ajusten adecuadamente en la ranura cuando se construyan las bobinas. 

Información del bobinado 

El número de grupos y bobinas se requiere para evaluar el bobinado. Aquí tenga cuidado con la matemática. Un ejemplo es un motor de 48 ranuras con 3 bobinas por grupo, en el cual el llenado de todas las ranuras es el mismo. Muchas veces este diseño se reporta como un bobinado concéntrico de 12 grupos y 4 bobinas por grupo con un total de 48 ranuras y tres pasos de bobina. Realmente existen 36 ranuras y la tercera bobina de cada grupo tiene el doble o casi el doble del número de espiras de las otras dos bobinas del grupo. En cada grupo de bobina, dos bobinas compartirán una ranura y la otra bobina llenará por completo una ranura. Esto puede causar confusión y muchas veces requiere de una llamada telefónica para aclarar lo que realmente hay ahí. 

La sección de los datos del alambre indica el número de alambres en paralelo y los calibres de cada bobina. Recuerde que el alambre redondo puede ser métrico o AWG. Si no está seguro, proporcione las medidas con micrómetro y nosotros tomaremos la decisión. Tenga en cuenta que si una máquina no está fabricada en Norte América, bien podría tener alambre métrico. Se debe evitar el uso de galgas ya que generalmente no cuentan con la suficiente precisión para poder determinar la diferencia entre los calibres medios o AWG versus los métricos. Incluso un alambre medio puede marcar la diferencia. Una mejor práctica consiste en medir el alambre con un micrómetro y utilizar la tabla de Alambres Redondos de EASA para identificar el calibre del alambre. 

Sin duda, la parte de este rompe cabezas que se reporta erróneamente con más frecuencia, es la conexión. Una buena regla a tener en cuenta es que si el motor tiene más de tres cables, existe más de una conexión. Una discusión acerca de esto y de cómo determinar la conexión, se encuentra en el artículo publicado en octubre de 2011 en la revista Currents titulado “Understanding three-phase motor connections.” 

Sera necesario contar las espiras en varios grupos de bobina ya que no es raro que exista un número de espiras diferentes en las bobinas de un mismo grupo o en grupos distintos. Algunas de estas pueden parecer impares, por lo que es bueno contar varios grupos de bobinas hasta que se identifique el patrón. El número de espiras será el número total de alambres dentro de la ranura dividido por los alambres en paralelo y el número de lados de bobina. Por ejemplo, en la ranura compartida de un bobinado excéntrico (imbricado) con 90 alambres dentro de la ranura y con 3#16, 2#17, el número de espiras es: 

90/2 = 9 espiras
( 3 + 2 ) 

El paso indica la ranura en la cual se aloja el primer lado de bobina y la ranura en la cual se inserta el lado opuesto. Ver Figura 3. Por lo que en un paso 1-8, el primer lado de bobina está insertado en la ranura 1 y el otro lado cae en la ranura 8. Un paso de bobina 1-8 abarca 7 dientes, por lo que la extensión de la bobina es igual a 7 (span). Todas las bobinas de ese grupo tendrán el mismo espacio entre ellas y a continuación comenzará la siguiente fase.

Figura 3

Los bobinados concéntricos siempre tendrán más de un paso, como 1-8, 10, 12. Éste es un grupo de tres bobinas que están concéntricamente anidadas como se ve en la Figura 4 a la derecha. No todas las potenciales combinaciones de paso permitirán una distribución equitativa de las bobinas y por consiguiente no se pueden utilizar. Por ejemplo, un motor de 4 polos con 48 ranuras y 36 bobinas no puede utilizar un paso 1-7, 9, 11 ya que la bobina a ranura llena caerá en la parte superior de la ranura de una bobina compartida y habrá ranuras vacías. 

Datos nuevos

Esta sección contiene las instrucciones de lo que usted desea obtener. Esto puede incluir cambios de potencia, velocidad, frecuencia o de voltaje. El motivo de la solicitud es muy importante ya que no necesitamos adivinar o suponer nada. Entre más detalles proporcione, especialmente en solicitudes complicadas, mejor serán los resultados. Si alguna información no está disponible, incluya una nota al respecto para que podamos hacer nuestro mejor esfuerzo para llenar los vacíos. 

Conclusión 

Entre más completa y exacta sea la información, recibirá una respuesta más rápida y precisa. Agradecemos mucho cuando nos envían al Departamento de Soporte Técnico de EASA sus solicitudes en línea o mediante los formatos que pueden descargar en la WEB. Al parecer cada centro de servicio tiene su propia forma de registrar esta información y esto es bueno. No obstante toma más tiempo encontrar la información cuando no estamos familiarizados con dichos formatos. Enviar la información en los formatos estandarizados por EASA acelera el proceso.

Information needed to complete a data verification & redesign request

Information needed to complete a data verification & redesign request

Jim Bryan
EASA Technical Support Specialist (retired)

In the February 2017 edition of Currents, Mike Parsons provided excellent advice on contacting EASA Technical Support with questions. Mike is with Hupp Electric Motors Co. in Marion, Iowa, and is a member of the Technical Education Committee. I would like to underline one statement he made: “You are not a bother!” In fact, you are our livelihood. 

Over the years, your Board of Directors has allocated resources to increase the number of technical support specialists. And in past Member Needs Assessment Surveys, members have consistently rated technical/engineering support as the number one benefit of membership. By all means, take advantage of it. 

To help you get the most from the benefit, this article will explain the information required to complete the Data Verification & Redesign Request form. You can complete and submit the request online or you may complete and fax or email the form that is available to download. See Figure 1. If the forms are filled out manually, be sure to write clearly. For example, numbers such as “1” or “7”, or “5” or “6”, can look the same if written too quickly.

Figure 1: EASA's Data Verification & Redesign Form

When completing both the printed and online forms, certain fields are marked with an asterisk (*) implying that they are required to complete your request. Sometimes all of this information is not available and should be noted so in the appropriate spot. We will then make every attempt to determine what should be done. 

Starting with the company information block, the important data are your company EASA identification number, a name and contact information in case we have questions. Let us know which medium you prefer to receive your response by filling in either the fax, email, or phone area. We use information in the manufacturer block to enter into the EASA database. While helpful for future reference, it will not impede the request if it is missing. 

Nameplate data 

*Hp or kW is the rating from the nameplate for the machine’s load capacity. When there are choices such as this, the correct unit should be circled. Entering rpm or poles and frequency determines the speed of the machine. Frequency, volts and amperes are also from the nameplate. If there is more than one of any of these values, all should be reported. 

Core data & dimensions 

One of the keys to evaluating or changing a design is to determine if the magnetic flux densities in the air gap and core iron are reasonable. This can be expressed in thousands of lines of flux per square inch (klines/in²) or Tesla (T). This is compared to the maximum values established for the air gap (65 klines/in² or 1T), core (130 klines/ in² or 2T) and tooth (130 klines/in² or 2T). They are also compared to motors with similar cores and ratings found in the EASA motor database. We can calculate the number of lines of flux per square inch using the voltage, frequency, winding data and core dimensions. The calculations require accurate measurements for each of the components as well as the number of stator slots. Figure 2 provides guidelines for these measurements.

Figure 2: Important information for taking measurements

The number of rotor bars is optional unless a speed change is requested. Depending on the number of poles, certain combinations of numbers of rotor bars compared to stator slots will produce noise, cogging or torque cusps. With the number of bars, we can check to see if the combination in your motor will be a problem. Note that if the rotor bars or stator slots are skewed, the combination should not cause these problems. 

The core length should be given as the overall distance from one end of the core to the other. If there are air ducts, the number and width of these can be reported in the spaces provided. They will then be included in the evaluation. 

For form coil windings, the stator slot dimensions are needed. Accurate measurements will facilitate designing the wire size and insulation to fit properly in the slot when the coil is made. 

Winding information 

The number of groups and coils is required for the winding evaluation. Be careful with the math here. An example is a motor with 48 slots with 12 groups of 3 coils, but all the slots are equally full. Many times this will be reported as 12 groups of 4 for 48 total coils with 3 pitches in the concentric winding. Actually, there are 36 total coils and the third coil in each group has twice or nearly twice the number of turns of the other two coils in the group. In each coil group, two coils will share a slot and one of the coils will fill the slot alone. It can be confusing and often require a phone call to clarify what is really there. 

The wire data section tells the number and size of the wires in hand for each turn. Remember the wire could be AWG or metric. If you are not sure, provide the micrometer readings for the wire sizes and we will make the determination. Note that if the machine is not made in North America, it well could be metric wire. Wire gauges should be avoided; they are generally not sufficiently accurate to determine the difference between half sizes or AWG versus metric sizes. Even a half wire size can make a difference. It is best practice to measure the wire with a micrometer and use the EASA Round Magnet Wire Data chart to identify the wire size. 

By far the most often misreported piece in this puzzle is the connection. A good rule to remember is that if the motor has more than three leads, there is more than one connection. A discussion of this and how to determine the connection is found in the October 2011 Currents article titled “Understanding three-phase motor connections.” 

Several examples should be taken to determine the number of turns in each coil; it is not uncommon for there to be different turns in the coils in the same group or for different groups. Some of these may seem odd, so it is good to count multiple coil groups until you recognize a pattern. The number of turns will equal the total number of strands (wires) in the slot divided by the number of wires in hand and the number of coil sides. For instance, in a shared slot lap winding with 90 total wires in the slot and 3#16, 2#17 the number of turns is: 

90/2 = 9 turns
(3+2) 

The pitch is the slot the first coil side falls in and the slot for the opposite side reached. See Figure 3. Such as in a pitch of 1-8, the first coil side is in slot 1 and the other side is in slot 8. A coil pitch of 1-8 spans 7 teeth, so the span = 7. All of the coils in that group will have the same space between them and then the next phase begins.

Figure 3: Coil pitch

Concentric windings will always have more than one pitch listed such as 1-8, 10, 12. This is a group of three coils that are concentrically nested as seen in Figure 4 at the right. Not all potential pitch combinations will allow the coils to be distributed evenly and therefore cannot be used. For instance, a 4-pole motor with 48 slots and 36 coils cannot use a pitch of 1-7, 9, 11; the full slot coil will fall on top of a shared slot coil and there will be empty slots. 

New rating 

This section contains the instructions for what you would like to accomplish. This may include changes in the horsepower, speed, frequency or voltage. The reason for the inquiry is very important so we do not need to guess. The more detail provided, especially for complicated requests, the better the results. If any of the information is not available, include a note to that effect so we can do our best to fill in the gaps. 

Conclusion 

The more complete and accurate the information provided, the more quickly and accurately the answer will be received. We very much appreciate when you submit your requests to EASA Technical Support online or using one of the downloadable forms. It seems that every facility has its own way to record this information and that is good. It does take extra time to find the information if you are not familiar with the format; submitting on standardized EASA forms expedites the process.

Interleaved windings provide useful alternative

Interleaved windings provide useful alternative

Chuck Yung
EASA Technical Support Specialist

Member Question: We recently received an 800 hp, 2-pole 460- volt motor for repair. It had a 4-Delta connection, and the windings show severe thermal stress. The customer confirmed that the motor was recently installed, drew high current, and failed quickly.

Internal Connection Diagrams for Three-Phase Electric Motors

Internal Connection Diagrams for Three-Phase Electric Motors

Internal Connection Diagrams coverEASA members can download a PDF of Internal Connection Diagrams for FREE. Use the link below for the free PDF.

This edition of EASA Internal Connection Diagrams contains significantly more connections than the previous version (1982), as well as improved templates for drawing connection diagrams. It provides internal connection diagrams for three-phase windings. It can be used with either concentric or lap windings. It also covers all possible parallels; wye and delta, 2 - 48 poles; part windings; two-speed windings; wye-delta and consequent-pole connections, 2 - 48 poles. It includes PAM connections, as well as triple- and quadruple-rated connections.

In terms of the number of connections, this edition covers more poles than before. It also now contains some less-common connections. These include the European pole amplitude modulation (PAM) design; multi-torque ratings; and part-salient, part-consequent pole connections that permit pole/slot combinations that otherwise would be unattainable.

Although the “by-the-numbers” method of drawing connections remains basically unchanged in this edition, the winding connection templates have been greatly improved. New templates for skip-pole and adjacent-pole diagrams also have been added to simplify drawing these connections. The jumpers are shown in gray with different line patterns for each phase. 

The book also includes templates for 2-pole through 30-pole, adjacent (1-4 jumpers) and skip pole (1-7) connections.

A printed version of this book is available for purchase in the online store.

Los programas AC Motor Verification and Redesign y Motor Rewind Data Version 4 trabajan en conjunto para ofrecer más funciones

Los programas AC Motor Verification and Redesign y Motor Rewind Data Version 4 trabajan en conjunto para ofrecer más funciones

Gene Vogel
Especialista de Bombas y Vibraciones de EASA

Las nuevas funciones del programa AC Motor Verification and Redesign – Version 4 (ACRewind) de EASA mejoran la capacidad de los miembros de EASA para enviar datos originales de forma electrónica e incluirlos en la base de datos Motor Rewind Data – Version 4 (MotorDB). Pase directamente a la sección “mejoras” si ya está familiarizado con los programas y cómo funcionan.

El software de la Version 4 es un conjunto de herramientas poderosas que sirve para que los miembros de EASA validen los datos de un bobinado, rediseñen devanados concéntricos a imbricados y efectúen cambios en los parámetros de un motor. Una característica clave de esta última versión del programa es la integración de la base de datos MotorDB con el programa ACRewind. La disponibilidad de ambas funciones del programa dentro de una interfaz de usuario común no es por simple conveniencia. La capacidad de los programas para compartir las fuentes de datos crea nuevas capacidades que la versión de cada programa independiente no podría.

Methods for three-phase winding data verification

Methods for three-phase winding data verification

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

One of the main objectives in rewinding is to maintain the original performance characteristics of the machine. Our focus with this article will be on three-phase motor stator windings. If it is known that the winding in the motor was original and there is certainty that the as-found data is correct, the original winding can be duplicated with confidence by using the as-found data. However, in some cases there is uncertainty that the as-found winding had original factory data. In those cases, extra steps need to be taken as described here.

Métodos para verificar los datos de un bobinado trifásico

Métodos para verificar los datos de un bobinado trifásico

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

Uno de los principales objetivos del rebobinado es poder conservar las características de funcionamiento originales de la máquina. Nuestro artículo estará enfocado en los bobinados de los estatores de motores trifásicos. Si se sabe que el devanado del motor era original y estamos seguros que los datos que hemos tomado son correctos, el bobinado original se puede duplicar con confianza utilizando estos datos. Sin embargo, en ciertas ocasiones, no existe la certeza que los datos que hemos tomado correspondan al bobinado original de fábrica. En estos casos, es necesario tomar medidas adicionales como las aquí descritas.

Motor connection tips for avoiding costly mistakes

Motor connection tips for avoiding costly mistakes

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, so successful installation depends on using the relevant connection diagram. If this information is lost, damaged, or ignored, a connection mistake could lead to a costly rewind.

The following tips apply to common connections on machines with one speed at power frequency. If the manufacturer's external connection diagram isn't available, ask a service center for assistance, especially if there are several missing lead tags, multiple speed ratings at power frequency, unconventional numbering, or NEMA-IEC cross-references.

READ THE FULL ARTICLE

Motor Rewind Data - Ver. 4

Motor Rewind Data - Ver. 4

This valuable resource is available only to EASA Members.

New Active and Allied members receive their first copy of this software FREE!

This version of the EASA Motor Rewind Database software takes a large leap forward with the data that it provides members. Most notably, it now has the ability to connect to a live, ever-expanding online database of more than 250,000 windings. This live database will be continuously monitored, updated and corrected as needed by EASA’s Technical Support Staff. Using the online database guarantees you’ll have the most up-to-date information available at all times. If your computer does not have an Internet connection, the software will automatically switch to the static, local database that was included and loaded during installation. (Note: The local database does not receive updates.)

The database includes:

  • Three-phase, single-speed AC motors
  • Three-phase, multi-speed AC motors
  • Single-phase AC motors
  • DC motors & generators

LEARN MORE ABOUT THIS TOOL

Operating a three-phase motor using single-phase power

Operating a three-phase motor using single-phase power

Chuck Yung
EASA Senior Technical Support Specialist

We all have that occasional customer who got a “deal” at an auction: a compressor, or lathe, or wood-working equipment, only to discover when he started to install it that this equipment has a three-phase motor and only single-phase power is available. Maybe it’s your neighbor or a friend from church. In any case, you know that you are about to be called upon to “convert” that piece of equipment, and you probably realize that it’s going to cost you more than you can charge.

Parallel circuits: More than meets the eye

Parallel circuits: More than meets the eye

Chuck Yung
EASA Senior Technical Support Specialist

There are benefits and drawbacks to the use of multiple circuits in a 3-phase winding. Whether discussing a random winding or form coil winding, some of the considerations are shared. Let’s start with the basics:  The higher the power rating, and/or the lower the voltage rating, the fewer turns/coil used. Because a 3-phase winding has pole-phase groups alternating ABC, ABC, ABC, etc., the intra-phase jumpers could be 1-4, 1-7, 1-10, 1-13, etc., or any combination of these so long as the alternating polarity of the groups is maintained and the phases are not cross-connected.

Powering up: Determining where to tap stator windings

Powering up: Determining where to tap stator windings

Cyndi Nyberg 
Former EASA Technical Support Specialist 

There are many applications where it is necessary for a low-voltage, single-phase AC or DC power supply to be available for auxiliary equipment such as brakes, clutches, lamps, etc., used along with a three-phase motor. The single-phase voltage can be supplied by tapping the stator winding at the correct place. DC voltage can be produced by tapping the single-phase or three-phase voltage from the three-phase winding and rectifying it to DC. Determining where to tap the winding is fairly straightforward. 

A three-phase stator winding, when energized, will have a certain number of volts per turn. That is, if you know the number of turns in each phase, and you know the phase voltage, you can determine the volts per turn. Knowing the number of volts per turn, and the required voltage supply for the auxiliary equipment, you can calculate pre­cisely where to tap the winding. 

Rediseño de Motores AC

Rediseño de Motores AC

Durante los últimos años, el rediseño de los motores eléctricos es un servicio que ha aumentado de popularidad en las compañías que reparan motores eléctricos. Al variar  uno o más datos del diseño, los centros de servicio muchas veces pueden adaptar motores para que cumplan con nuevos requisitos de forma más rápida y económica  que al comprar motores nuevos.
El manual de Rediseño de Motores de CA de EASA explica  la forma de realizar todos los cambios posibles en los valores nominales de los motores eléctricos de CA dentro de sus limitaciones de diseño. Además de fórmulas matemáticas, este manual proporciona directrices relacionadas con las limitaciones propias de cada tipo de rediseño, que  le ayudarán a determinar  si es posible obtener un nuevo valor nominal antes de retirar el bobinado. Los términos se expresan en Español y en unidades métricas y cada capítulo contiene al menos un ejemplo para guiarlo durante sus propios rediseños.

Los miembros de EASA pueden descargar GRATIS este  libro  o pueden comprar copias impresas del mismo.                                                                         

Los capítulos del libro incluyen:

  • Cambio del  tamaño del conductor
  • Cambio de Voltaje 
  • Cambio de Potencia
  • Cambio de Frecuencia
  • Cambio del Número de  Fases
  • Cambio de los Circuitos en Paralelo
  • Cambio de  Paso o del Factor de Cuerda
  • Cambio en la conexión del bobinado
  • La fórmula maestra
  • Conversión de bobinados concéntricos en imbricados
  • Conversión de bobinados imbricados en concéntricos
  • Notas para el cambio del número de polos
  • Disminución de la velocidad aumentando el número de polos
  • Aumento de la velocidad disminuyendo el número de polos
  • Una velocidad a dos velocidades con un solo devanado
  • Una velocidad a dos velocidades con dos bobinados
  • Cálculo de un bobinado para un núcleo sin datos
  • Fortaleciendo o debilitando el motor- método corto
  • Determinando la conexión apropiada
  • Rediseño monofásico
  • Cálculo del voltaje secundario
  • Determinando el agrupamiento trifásico de las bobinas 

Rewinding Tips for Premium-Efficient Motors

Rewinding Tips for Premium-Efficient Motors

This webinar recording covers: 

  • Importance of core loss testing
  • Methods to reduce core losses
  • Slot fill improvement without reducing copper

Skip-pole or adjacent-pole: Does jumper configuration really matter?

Skip-pole or adjacent-pole: Does jumper configuration really matter?

Chuck Yung
EASA Senior Technical Support Specialist

One of the recurring questions asked of EASA technical support specialists is:  “Should I use 1-4 or 1-7 jumpers?” This article is a tutorial on jumper selection to help the reader recognize when it does – or does not – matter. 

Let’s start with a short review for the experienced winders and good fundamentals (Table 1) for the newer winders. First, three-phase windings are symmetrical. The connection is log­ical if we apply some basic rules. The groups are positioned symmetrically, in sequence of A-B-C-A-B-C, with an equal number of coil groups required in each phase.

Squirrel cage motors: Three most common starting methods

Squirrel cage motors: Three most common starting methods

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

The most common method of start­ing squirrel cage three-phase motors is across the line (direct-on-line). Some applications require limiting the mo­tor starting current and/or torque to reduce the stress on the electrical and mechanical systems. 

Although there are other meth­ods such as autotransformer, reactor and using a variable frequency drive (VFD), the focus in this article will be on the reasons behind the selection of the three most common methods of achieving these objectives. Specifically, these methods are part winding, wye-delta, and electronic soft-starting. The windings in all three of these methods usually have 6 leads.

Start new year off right by getting back to basics

Start new year off right by getting back to basics

Cyndi Nyberg Esau
Former EASA Tenchincal Support Specialist

As we move into January, it's time to put into practice those New Year's resolutions we made. Many of us have the same ones every year. You know: eat less, exercise more, spend more time with the family, etc. However, rather than personal challenges, presented here are the"resolutions" for some of the more common calls we receive in the Technical Support Department at EASA Headquarters. A review of the basics is always a good idea to start the new year fresh!

Taking data: How to correctly identify the connection

Taking data: How to correctly identify the connection

Chuck Yung
EASA Senior Technical Support Specialist
 
When taking winding data, the area most prone to error is in identifying the connection. This article includes a reference page (see Figure 1) that I encourage you to print and laminate for the winders to use.

Taking Three-Phase Winding Data

Taking Three-Phase Winding Data

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.

Taking winding connection data on alternators

Taking winding connection data on alternators

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

We will begin this article by clarify­ing the terms “alternator” and “gen­erator.” Both terms refer to a machine that converts mechanical to electrical power. An alternator is a synchronous machine that converts mechanical to AC electrical power. A generator is a more general term and is a machine that converts mechanical to electrical power, either AC or DC. An alternator is always a generator, but not vice-versa. Our focus in this article will be on 3-phase alternators. However, much of the information provided also applies to single-phase alternators and single- or three-phase generators.

The (potential) pitfalls of parallel circuits

The (potential) pitfalls of parallel circuits

Editor's Note: This "encore" technical article first appeared in the September 2003 issue of Currents. It was written by former Technical Support Specialist Cyndi Nyberg Esau.

To make more efficient use of time and materials, winders may want to increase the number of parallel circuits when winding an AC stator (or wound rotor). However, there are limits to the number of parallel circuits that can be used in an AC stator (or wound rotor) design. In this article, some of the potential problems associated with increasing the number of parallel circuits will be analyzed.

If the original design of a mo­tor has few turns with large wires, or many wires in hand, it may be easier to rewind if the number of parallel circuits can be increased (see Figure 1). Doubling the circuits, for example, doubles the turns per coil and cuts in half the wire size or the number of wires in hand. Of course, doubling the circuits also doubles the volts per coil.

The Basics: AC Motor Design

The Basics: AC Motor Design

This webinar recording covers: 

  • Various types of AC motors and bases for operation
  • Squirrel cage induction motor rotor design / construction
  • Squirrel cage induction motor stator design / construction

The Basics: Motor Connections

The Basics: Motor Connections

This webinar covers:

  • Internal connections
  • Connections in the outlet box
  • Connections in the MCC Ladder diagrams 

The Basics: Taking Motor Data

The Basics: Taking Motor Data

This webinar covers:

  • Photo documentation
  • Paper documentation
  • Measurements
  • Winding data: turns, wire size, connection, core dimensions
  • Keeping cause of failure questions in mind 

The potential pitfalls of parallel circuits

The potential pitfalls of parallel circuits

Cyndi Nyberg 
Former EASA Technical Support Specialist 

To make more efficient use of time and materi­als, winders may want to increase the number of parallel circuits when winding an AC stator (or wound rotor). However, there are limits to the num­ber of parallel circuits that can be used in an AC stator (or wound rotor) design. In this article, some of the potential problems associated with increas­ing the number of parallel circuits will be analyzed. 

If the original design of a motor has few turns with large wires, or many wires in hand, it may be easier to rewind if the number of parallel cir­cuits can be increased. Doubling the circuits, for example, doubles the turns per coil and cuts in half the wire size or the number of wires in hand. Of course, doubling the circuits also doubles the volts per coil. 

Tips and Techniques for Winders

Tips and Techniques for Winders

This webinar covers:

  • Procedural tips for coil insertion
  • Creating slot room where there is none
  • Faster, easier separators
  • Lacing technique to prevent phase paper pull-out
  • Interspersed coil winding made simple
  • Better braze joints

Trabajando con bobinados con espiras diferentes (impares)

Trabajando con bobinados con espiras diferentes (impares)

Mike Howell
EASA Technical Support Specialist

Cuando sus procesos pueden facilitarlo y para rebajar costos de fabricación, los fabricantes casi siempre emplean en los estatores trifásicos de alambre redondo, bobinados concéntricos insertados con máquinas. Muchos centros de servicio también pueden rebobinar bobinados concéntricos, pero la práctica más común es la de utilizar bobinados excéntricos de doble capa. Para los estatores con bobinas pre-formadas, los fabricantes y los centros de servicio utilizan la mayoría de las veces, bobinados excéntricos de doble capa.

La finalidad de este artículo es proporcionar algunos consejos para trabajar con bobinados con espiras diferentes (impares) o con bobinados excéntricos de doble capa donde el número de espiras por ranura es un número impar (Ej. 3,5,7,9…n). En estos casos, los lados superior e inferior de la bobina deben tener un número de espiras diferente.

Training Film 1: Taking Winding Data From a Three-Phase Induction Motor

Training Film 1: Taking Winding Data From a Three-Phase Induction Motor

Teaches how to determine type of connection, number of parallel circuits, turns per coil, wire size, span and groups. Shows step-by-step way to properly record all information.

This training film is archived here solely for historical purposes. The film was produced many years ago and does not meet EASA's current presentation standards. Some procedures may have also changed.

Una mirada más detallada a las conversiones de bobinados por reconexión

Una mirada más detallada a las conversiones de bobinados por reconexión

Cuando un cliente solicita que un motor sea rebobinado para una nueva serie de condiciones, esto es lo que nosotros habitualmente le proporcionamos en la industria de los centros de servicio. No obstante, existen ocasiones en las que lo requerido por el cliente se puede llevar a cabo por reconexión; en algunos casos, esto se hace simplemente revisando los datos de placa del motor. El propósito de este artículo es identificar y explicar algunos de estos escenarios.

Las reconexiones cubiertas incluyen:

  • Arranque por devanado partido (PWS)
  • Un solo voltaje-12 cables
  • 2 estrellas y 1 delta 230/460-575 voltios
  • 380 voltios - 50 Hz y 460 voltios - 60 Hz
  • 2300 y 4000 voltios

​Para una referencia adicional, ver "Variables a Considerar Cuando Cambiamos La  Frecuencia de  Un Motor Entre 50 y 60 Hz" publicado en Noviembre de 2008.

Understanding three-phase motor connections

Understanding three-phase motor connections

Choice of wye or delta connection, number of circuits play an important role

Jim Bryan
EASA Technical Support Specialist (retired)

The connection of a three-phase motor is one of the many variables a motor designer can use to optimize the performance and life of the machine. The designer determines whether to use a wye or delta connection and how many parallel circuits to maximize current density (circular mils per amp or cm/A) while optimizing flux densities and manufacturability.

In three-phase motors, the square root of three is an important number. Because of the phase relationships of the three windings shown in Figure 1, the voltage and current are intertwined with this factor. In the delta winding, the phase voltage is applied to each phase winding but the current has two possible paths. Due to the phase relationship of the winding, the current is not split in two but by the square root of three (1.73). The opposite is true for the wye connection; the phase voltage impressed on each phase is the line voltage divided by 1.73, and the phase current equals the current in each coil. This is the reason that wye wound motors have fewer turns of heavier wire than do delta-connected motors.

Windings & Connections

Windings & Connections

This webinar recording focuses on the internal connections of AC motors, including:

  • Wye or delta?
  • Parallel circuits
  • Dual voltage - delta connected, wye connected and wye/delta connected
  • Tri-voltage - 2D2Y1D and others

Working with AC Windings

Working with AC Windings

12
presentations
$60
for EASA members

 

A special discounted collection of 12 webinar recordings focusing on AC motor windings.

Once purchased, all 12 recordings will be available on your "Downloadable products purchased" page in your online account.

Downloadable recordings in this bundle include:

The Basics: Taking Motor Data
Presented September 2016

This presentation covers:

  • Photo documentation
  • Paper documentation
  • Measurements
  • Winding data: turns, wire size, connection, core dimensions
  • Keeping cause of failure questions in mind

Taking Three-Phase Winding Data
Presented October 2012

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.


The Basics: Motor Connections
Presented November 2016

This webinar covers:

  • Internal connections
  • Connections in the outlet box
  • Connections in the MCC Ladder diagrams

Tips and Techniques for Winders
Presented August 2015

This webinar covers:

  • Procedural tips for coil insertion
  • Creating slot room where there is none
  • Faster, easier separators
  • Lacing technique to prevent phase paper pull-out
  • Interspersed coil winding made simple
  • Better braze joints

Rewinding Tips for Premium Efficient Motors
Presented June 2016

This webinar recording covers: 

  • Importance of core loss testing
  • Methods to reduce core losses
  • Slot fill improvement without reducing copper

Windings & Connections
Presented December 2015

This webinar recording focuses on the internal connections of AC motors, including:

  • Wye or delta?
  • Parallel circuits
  • Dual voltage - delta connected, wye connected and wye/delta connected
  • Tri-voltage - 2D2Y1D and others

Concentric or Lap? Considerations for the 2-Pole Stator Rewind
Presented September 2014

Two-pole motors present special rewind issues, especially when converting them from concentric to lap windings. The pitch is especially important as certain coil pitches will cause harmonics that have a negative impact on performance. Optimum pitches are often very difficult to wind and shorter pitches result in sacrificed conductor area.

This presentation explores sample redesigns and present some guidelines to assist in deciding between the concentric and lap winding.

Target audience: This webinar will be most useful for service center winders, engineers, supervisors and managers. The content will be beneficial for beginners through highly experienced persons.


Stator Rewinds: When Things Get Tight
Presented June 2015

When preparing to rewind random or form wound stators, sometimes there just doesn’t seem to be enough room in the stator slot for the desired conductor area and insulation quantities. Common scenarios encountered are redesigns from concentric to lap, changes to higher voltages or aggressive designs from the OEM.

This webinar will look at balancing stator copper losses against insulation reliability.


Ensuring Success With VPI
Presented June 2014

Global vacuum pressure impregnation is the most common insulation system processing method utilized for form wound stators today. A successful VPI depends on several variables including materials, methods and maintenance. This recording will provide information to assist the service center with ensuring success with form wound VPI projects.

Target audience: This recording will be most useful for service center winders, engineers, supervisors and managers. The content will be beneficial for beginners through highly-experienced persons.


Induction Motor Rotor Windings: Squirrel-Cage and Wonld Rotor Basics
Presented January 2018

This presentation covers the following topics:

  • Induction motor basics for operation
  • Squirrel-cage
    • Conductor material
    • Deep-bar effect
    • Multiple-cage windings
    • Phase resistance
    • IEC/NEMA design letters
    • Speed-torque characteristics
  • Wound-rotor
    • Winding construction
    • Wave-wound connections
    • Distribution factor and chord factor
    • Rotor phase voltage
    • Speed-torque characteristics

Target audience: This webinar will benefit service center technicians and supervisors. 


2-Speed, 2-Winding Pole Group Connections
Presented September 2018

The topics covered included in this webinar recording:

  • One circuit wye connection — Best, no parallel paths, turns per coil may prevent this
  • Delta or multiple parallel circuits—Produces closed circuits, Circulating currents
  • Open delta (4 wire connection)
  • Permissible connections—Skip pole, adjacent pole
  • Determined by speed combination

T​arget audience: This webinar recording will benefit service center technicians and supervisors.


Minimizing Risk With High-Voltage Rewinds
Presented February 2014

This webinar presents a product quality planning process for industrial motor stator windings rated above 4 kV. Emphasis is placed on analyzing gaps between these projects and lower voltage rewinds as they relate to:

  • Stator winding design
  • Insulation system validation
  • Process control

Target audience: This presentation is most useful for service center winders, engineers, supervisors and managers. The content targets beginners through highly experienced persons.

Working with odd-turn (unequal-turn) windings

Working with odd-turn (unequal-turn) windings

Mike Howell
EASA Technical Support Specialist

Manufacturers almost always utilize machine-inserted concentric windings for random-wound, three-phase stators when their processes can facilitate it due to lower manufacturing costs. Many service centers can produce concentric windings too, but the most common practice is to utilize the two-layer lap winding. For form-wound stators, the two-layer lap winding is almost always used by manufacturers and service centers alike.

The purpose of this article is to provide some tips for working with odd-turn (unequal-turn) windings, or two-layer windings where the total number of turns per slot is an odd number (e.g., 3,5,7,9…n).