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Articles in Industry Publications

Core Repair Tips To Reduce Core Loss

  • August 2024
  • Number of views: 1598
FREE for Members of EASA
Webinar recording

When a core loss test reveals localized hot spots, or visual inspection identifies physical damage, the ability to repair the damage in a cost-effective manner means the difference between repair or replacement.

Crooked Teeth? We’ve Got Braces!

How Using Clamps When Pulling Magnet Wire Helps Prevent Splayed Teeth

  • January 2024
  • Number of views: 1596
Article

Unless great care is taken, pulling magnet wire from a motor stator often bends or splays the lamination’s end teeth. Bent teeth, or teeth that have been splayed outward at the ends of the core stack, will likely compromise the quality of the repair job. Therefore, we have designed and implemented the use of disc clamps to hold the stator tooth tips in place while pulling magnet wire from the slots. The clamping fixtures described in the photos have helped ensure that we avoid damaging the stator teeth during the stripping process.

¿Dientes Torcidos? ¡Tenemos Ortodoncia!

Cómo el usar discos de retención al tirar del alambre magneto previene doblar los dientes de las laminaciones

  • January 2024
  • Number of views: 1201
Article

A no ser que se tenga mucho cuidado, tirar del alambre magneto al desmantelar el estator de un motor a menudo deforma o dobla los dientes de las laminaciones. Estos dientes deformados comprometerán la calidad de la reparación y hay estudios que demuestran que este problema puede reducir la eficiencia del motor. Sin embargo, aunque esta reducción puede ser pequeña, genera altos costos y desperdicio de energía.

Taking Proper Measurements for Re-stacking Stator Cores Featuring Vents

  • May 2023
  • Number of views: 2324
Article

There are many factors to consider when re-stacking a stator. Those include the materials, core compression, length of the core, vents, spacers, vent construction and more. This article focuses on taking proper measurements when re-stacking a stator core and how to go about stacking the stator to ensure those dimensions are met.

Tomando las Medidas Adecuadas para Re apilar Núcleos de Estatores con Orificios de Ventilación

  • May 2023
  • Number of views: 4209
Article

Hay muchos factores que se deben considerar al re apilar el núcleo del estator. Estos incluyen los materiales, la compresión y largo del núcleo, los orificios de ventilación, los espaciadores, la construcción de los orificios de ventilación y más. Este artículo se centra en tomar las medidas adecuadas para volver a apilar el núcleo de un estator y cómo garantizar que se cumpla con esas dimensiones.

Working with Segmented Stator Cores

  • February 2022
  • Number of views: 9028
Article

Induction motor stator cores can be manufactured using single-piece laminations, however, for larger stators, or when minimizing scrap material, the stator laminations are segmented. While most service center repairs of machines with segmented stator laminations require no special attention, this article reviews a few scenarios that are important to be mindful of.

Trabajando con Estatores con Núcleos Segmentados

  • February 2022
  • Number of views: 6479
Article
Los núcleos de los motores de inducción se pueden fabricar con laminaciones de una sola pieza, sin embargo, para estatores muy grandes o cuando se minimiza el material de desecho, las laminaciones del estator son segmentadas.  Aunque la mayoría de las reparaciones en el centro de servicio de  las máquinas con estatores con laminaciones segmentadas no requieren atención especial, este artículo analiza algunos escenarios que es importante tener en cuenta.

How to Test and Assess Stator Core Condition Using a Loop Test

  • April 2020
  • Number of views: 20575
FREE for Members of EASA
Webinar recording

Is the motor drawing high no-load amps and winding data are correct? Are you experiencing unusual heating of the stator under load? Those common questions can be answered by checking the stator core condition.

Cómo Probar y Evaluar la Condición del Núcleo de un Estator con la Prueba de Lazo (“Toroide” o Loop Test)

En Español

  • April 2020
  • Number of views: 15758
FREE for Members of EASA
Webinar recording

¿El motor consume mucha corriente en vacío, aunque los datos del bobinado son correctos? ¿El motor se calienta con carga de forma inusual? Estas son preguntas comunes que pueden ser resueltas verificando la condición del núcleo del estator. En este webinario discutiremos cómo realizar la prueba de lazo en el núcleo de un estator y cómo analizar los resultados obtenidos, proporcionando información sobre los equipos utilizados, consejos para reparar el núcleo del estator y otras pruebas alternativas.

What watts, what pounds? Working with stator core test results

  • November 2019
  • Number of views: 9744
Article

The two primary reasons for performing stator core testing in the service center are (1) to verify that the stator core is acceptable for continued use and in the event of a rewind, and (2) to verify that the repair process has not adversely changed the stator core condition. The purpose of this article is to discuss how we determine, assess and compare stator core test results. It is extremely important to understand that variance in test procedures may invalidate comparison.

¿Cuántos vatios, cuántas libras? Trabajando con los resultados de la prueba de núcleo del estator

  • November 2019
  • Number of views: 7641
Article

Las dos razones principales para realizar la prueba de núcleo del estator en el centro de servicios son (1) verificar que el núcleo del estator es apto para uso continuo y en caso de rebobinado y (2) verificar que el proceso de rebobinado no ha alterado de forma adversa la condición del núcleo del estator. El propósito de este artículo es discutir como determinar, evaluar y comparar los resultados de la prueba de núcleo. Es muy importante comprender que la variación de los procedimientos de prueba puede invalidar la comparación.

Stator Core Test Form

  • September 2019
  • Number of views: 15486
Form/Worksheet

EASA’s Stator Core Test Form provides a step-by-step procedure for calculating the number of turns and cable size required for a loop test.

How To Wind Three-Phase Stators (Version 2)

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

  • February 2017
  • Number of views: 16169
Software

This EASA software is a valuable interactive training tool ideal for training your novice(s) ... and even experienced winders will learn from it. The CD teaches how to wind in a richly detailed, step-by-step approach which includes narrative, animations and video clips, with tests to assess student comprehension. 

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The Basics: AC Motor Design

  • July 2016
  • Number of views: 8846
Webinar recording

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
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Keeping it cool: A look at causes of motor overheating

  • March 2015
  • Number of views: 15551
Article

We know that excessive temperature and moisture are the largest contributors to bearing and winding failures. Understanding the source of the increased temperature will help us to correct the problem and improve the machine’s life expectancy.

The importance of stator core loss testing before and after burn-off process

  • June 2014
  • Number of views: 16158
Article

By this time we should all know that stator core loss testing is a required part of a quality rewind. A core loss test before and after burn-off is specified in the EASA Recommended Practice for the Repair of Rotating Electrical Apparatus (ANSI/EASA AR100) and The Effect of Repair/Rewinding on Motor Efficiency; EASA/AEMT Rewind Study and Good Practice Guide to Maintain Motor Efficiency.

Topics covered in this article include:

  • Lessons learned
  • Rebates add incentive
  • Learning from other members
  • Determining if the core is usable
  • Accurate iron measurements

Guidelines for Maintaining Motor Efficiency During Rebuilding

  • November 2007
  • Number of views: 11133
Article

The challenge for every motor repair firm is twofold: to repair the equipment properly, and to demonstrate to their customers by means of adequate testing and documentation that rewound motors retain their operating efficiency. Following the guidelines in this document will help you accomplish both.

To ensure that motors retain their efficiencies when rewound, EASA also strongly recommends that electric motor repair centers comply with ANSI/EASA Standard AR100: Recommended Practice For The Repair Of Rotating Electrical Apparatus and strictly adhere to the “DOs” and “DON’Ts” presented in this article. These guidelines, which contain safe values (based on available data) and correct procedures, apply to both energy efficient and standard motors. Further study of the matter continues, and these guidelines will be revised if additional information warrants.

Electrical steels: Processes, types and properties

  • July 2005
  • Number of views: 5788
Article

Most rotor, stator and armature laminations used in industrial electric motors and generators are made from non-oriented, cold-rolled electrical steels. However, there is a lot of variation in the specific properties in these electrical steels. This article will discuss properties of electrical steels, as well as the methods used to optimize the magnetic characteristics of the laminations, specifically through the annealing process.

Motor (stator core) restacking procedures

  • July 1999
  • Number of views: 10553
Article

You've just dismantled a special motor for a customer, and the core test indicates the watts loss/pound is excessive.  The high core losses are caused by shorts between the laminations.  This may be the result of a ground failure.  Or excessive temperatures may have caused the deterioration of inter-laminar insulation (called coreplate.)

Whatever the cause, a replacement is 16 weeks away, and your customer wants his motor repaired.  This motor sounds like a prime candidate for a restack, but you are hesitant.  Your company has a reputation for quality, and the finished product has to meet your usual high standards. 

You want to know the best procedure for repairing this core.  Here are some guidelines to help you do the best possible repair.