Chuck Yung
Especialista Sénior de Soporte Técnico de EASA

Uno de los temas más debatidos en nuestra industria es la comparación- y los procedimientos- de impregnación por presión y vacío (VPI) versus la inmersión y secado en horno. En este artículo, he ampliado la discusión para incluir bobinas semicuradas (B-stage) y el método de goteo (trickle). Los centros de servicio que cuentan con un tanque de VPI resaltarán rápidamente los muchos beneficios del VPI, como un mejor sellado de los devanados y una mejor transferencia de calor entre los conductores de los bobinados y la carcasa para mejorar la disipación de calor.

Los bobinados de pletina (solera/bobinas formadas) y de alambre redondo tienen dos problemas claramente diferentes. Para las máquinas con bobinas de pletina, la penetración de la resina es la mayor preocupación, lo que le brinda una clara ventaja al proceso VPI. En los bobinados de alambre redondo, la inquietud es la retención de la resina.

Mike Howell
EASA Technical Support Specialist

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?

Mike Howell
EASA Technical Support Specialist

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?

This presentation demonstrates an easy-to-build temporary oven that can be constructed in the service center or in site. The recording covers:

• Materials to use and where to obtain
• Heating: electric, propane, or other?
• Measuring winding temperature
• Regulating oven temperature
• Storage of the parts when not in use
• Safety concerns and cautions

Target audience: This presentation will benefit service center supervisors and management.

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

Mike Howell
Especialista de Soporte Técnico de EASA

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). Resumiendo, los EIM son materiales idóneos para separar las partes conductoras a diferentes voltajes y los EIS son estructuras aislantes que contienen uno o más de estos materiales.

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. Por ejemplo, es posible que dos materiales (EIM) clasificados individualmente como clase H (180ºC) tengan vida térmica en un sistema (EIS) limitado a una clase térmica F (155ºC).

Mike Howell
EASA Technical Support Specialist

Relevant standards including IEC 60085 and IEEE 1 have similar definitions for electrical insulating materials (EIM) and electrical insulation systems (EIS). To summarize, EIM are materials suitable for separating conducting parts at different voltages, and EIS are insulating structures containing one or more of these materials.

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. For example, it is possible for two materials (EIM) classified individually at thermal class H (180°C) to have thermal endurance in a system (EIS) limited to thermal class F (155°C). Far worse outcomes could exist if material compatibility is an issue. At the service center level, our resources are generally insufficient for these types of insulation system development activities. For this reason, two approaches often seen are (1) relying on a third party (e.g., resin manufacturer) to provide a qualified insulation system bill of materials, or (2) applying commonly used materials based on their individual ratings. The first approach is strongly recommended, and the second approach can lead to disaster.

Chuck Yung
EASA Senior Technical Support Specialist

Have you ever had a curing issue with your DAP monomer (diallyl-phthalate ) solventless resin (hereafter referred to as resin for simplicity)? If you haven’t, read on for guidance on preventing issues in the future. If you have, this article provides guidance on correcting the issues as well. 

As expensive as resin is, all service centers should be diligent about the care of their resin dip tank and VPI (vacuum pressure impregnation) systems.

Chuck Yung
EASA Senior Technical Support Specialist

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, I have expanded the discussion to include trickle epoxy and B-stage coils. Service centers that have a VPI tank will quickly point out the many benefits of VPI, such as better sealing of the windings and improved heat transfer from the winding conductors to the frame for enhanced heat dissipation.

Form and random windings have two distinctly different issues. For the form-wound machine, resin penetration is the biggest concern – giving a clear advantage to a VPI process. For random windings, the concern is retention of the resin.