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.

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.

This handy form provides fields to record all of the details needed to document and/or order replacement coils for an AC form-wound machine. The form also includes detailed descriptions/definitions of the data to be recorded in each field. 

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 started as an article to explain those cases where a 2-pole winding concentric-to-lap conversion will not run. The cause has to do with the coil pitch selected and slot spatial harmonics. These harmonics have a harmful effect on motor performance. The key is avoiding certain coil pitches, and the "problem" 2-pole pitch depends on the number of slots and the coil pitch. To make the article more useful, it includes tables to identify "preferred" coil pitches for2-pole, 3-phase windings, as well as those that should be avoided.