The insulation system chosen for any rewind should be suitable for the application, the voltage class, and the winding process capability of the service center. In most cases, adherence to “equal to or better than” selection is a good practice.

El sistema de aislamiento escogido para cualquier rebobinado debe ser el adecuado para la aplicación, el voltaje y la capacidad del proceso de rebobinado del centro de servicio. En la mayoría de los casos, seleccionar una opción "igual o mejor" es una buena práctica.

This video explains how to check the ground insulation of an AC motor winding using the insulation resistance (IR) test.

The goal of vacuum pressure impregnation is complete saturation of a winding with insulating resin. As resin penetrates the insulating materials, it causes them to darken. If some insulation is a lighter shade, the coil or jumper is not fully saturated. The winding is not properly protected, and if the problem is not addressed, it is likely to cause premature failure of the unit. This could result in costly warranty work, or at a minimum, will be a failure to provide your customers with the quality they expect and deserve.

El objetivo de la impregnación por vacío y presión (VPI) es saturar completamente un devanado con resina aislante. A medida que la resina penetra en los materiales aislantes, los oscurece y al drenar la resina VPI del devanado, todo el aislamiento de las cabezas queda oscuro en un tono uniforme. El aislamiento de la conexión también debe quedar oscuro de forma pareja. Si algún aislamiento muestra un tono más claro, la bobina o el puente no han quedado completamente saturados y el devanado no está debidamente protegido. Si no se soluciona el problema, es probable que esto provoque un fallo prematuro en el equipo. Esto podría generar una garantía costosa o, como mínimo, la reparación no brindará a sus clientes la calidad que esperan y merecen.

One of the most briskly debated issues in our industry is the comparison – and procedures for – vacuum pressure impregnation (VPI) versus dip & bake. For this article, the discussion has been expanded to include trickle epoxy and B-stage coils.

Uno de los temas más debatidos en nuestra industria es la comparación y los procedimientos de impregnación a presión al vacío (VPI) versus inmersión y horneado. Para este artículo, la discusión se ha ampliado para incluir bobinas de etapa B y epoxi de goteo.

Relevant standards including IEC 60085 and IEEE 1 have similar definitions for electrical insulating materials (EIM) and electrical insulation systems (EIS). As with any system, there is an interaction between the materials used, and the insulation system developers take great care to ensure that this interaction does not lead to undesirable outcomes.

Diferentes normas relevantes incluyendo la IEC 60085 y la IEEE 1 definen de forma similar los materiales electro aislantes (EIM) y los sistemas de aislamiento eléctrico (EIS). Como en cualquier sistema, existe una interacción entre los materiales usados y los diseñadores de los sistemas de aislamiento cuidan todos los detalles para evitar que esta interacción produzca resultados indeseados.

This webinar recording reviews the failures associated with 3-phase motors on Variable Frequency Drives (VFDs) and how to rewind to limit future failures.

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.

A special discounted collection of 11 webinar recordings focusing on AC motor electrical procedures.

Just $55 for EASA members!

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

Just $60 for EASA members!

High-potential testing is routinely used to assess the ground insulation of AC stator windings in-process, after completion of a rewind and post-delivery. This webinar covers types of high-potential tests, testing standards, evaluating test results, and more.

One of the least popular tasks to perform related to winding treatment processes is preparation and cleanup of fits, threaded holes and machined surfaces. Many service centers invest additional time in the preparation stage so as to minimize the cleanup stage. The most common approach to protecting these surfaces during winding treatment is to utilize masking compounds or dry release sprays.

In the last year, EASA’s technical support staff has received a number of inquiries from members seeking replacement recommendations for Famous Lubricants' “Special Masking Compound” which is currently unavailable. It is believed at this time that the manufacturer intends on continuing production at some point in the future though the time frame is not known. This specific problem leads to a more general question: What is a good practice for choosing a product to mask these surfaces?

Una de las actividades a realizar menos populares relacionadas con el tratamiento de los bobinados, es la preparación y la limpieza de los ajustes, agujeros roscados y superficies mecanizadas. Muchos centros de servicio invierten tiempo adicional durante la etapa de preparación para minimizar la etapa de limpieza. El enfoque más común para proteger estas superficies durante el tratamiento del bobinado consiste en utilizar compuestos para enmascarar o aerosoles de liberación de película seca. Durante el último año, el departamento de soporte técnico de EASA ha recibido una serie de consultas por parte de los miembros buscando recomendaciones para reemplazar el producto “Special Masking Compound” de Famous Lubricants’ (ver Figura 1) que actualmente no se encuentra disponible. Se cree en estos momentos que el fabricante tiene la intención de continuar con la producción en el futuro, aunque el plazo se desconoce. Este problema específico conlleva a una pregunta más general: ¿Cuál es una buena práctica para escoger un producto para enmascarar estas superficies?

This presentation covers induction motor basics for squirrel-cage and wound rotor motors

The power factor tip-up test is commonly used as a quality measurement for new coils and windings manufactured for AC motors and generators rated 6 kV and higher. It can also be useful in the rewind shop to verify the quality of a newly-installed coil system including the effectiveness of VPI processing.

La prueba de volcado del factor de potencia se usa comúnmente como una medida de calidad para bobinas y devanados nuevos fabricados para motores de CA y generadores con clasificación de 6 kV y más. También puede ser útil en el taller de rebobinado para verificar la calidad de un sistema de bobina recién instalado, incluida la efectividad del procesamiento de VPI.

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. 

This webinar covers:

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

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

This webinar recording covers: 

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

The Institute of Electrical and Electronics Engineers (IEEE) standard for insulation resistance testing of motor and generator windings that was published in 2002 has been revised. The 2013 edition was published in March 2014. This article examines the changes to the standard.

La norma para realizar las pruebas de resistencia de aislamiento en los devanados de motores y generadores del Instituto de Ingenieros Eléctricos y Electrónicos (IEEE), publicada en el 2002 ha sido revisada. La edición del 2013 fue publicada en Marzo del 2014. Este artículo examina los cambios al estándar.

This webinar recording covers:

• Insulation system versus insulation materials
• Stresses imposed on insulation systems
• Insulation system components / functions
• Typical testing of system components / functions

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.

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.

This paper, presented at the 2014 EASA Convention, describes research done by EASA service shops on the effectiveness and practicality of using offline partial discharge combined with a dielectrics characteristic test to evaluate the consolidation of stator windings in medium voltage machines manufactured by GVPI.

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