¿Recibió un motor antiguo bobinado con alambre de aluminio? Este webinario explicará como realizar la conversión adecuada de alambre de aluminio a alambre de cobre en máquinas de CA y CC, incluyendo ejemplos para el rebobinado de estatores y campos shunt.

EASA recommends using the lead wire specified by the original equipment manufacturer (OEM) whenever possible. If not available, some guidance is provided in section 6 of the EASA Technical Manual and an online calculator is available to determine a minimum recommended size based on temperature rating, expected current, number of leads and type of connection. This article will describe the calculator’s function.

EASA recomienda usar el cable de salida especificado por el fabricante original del equipo. Si no está disponible, la sección 6 del Manual técnico de EASA proporciona orientación al respecto y hay una calculadora en línea disponible en go.easa.com/calculators para determinar el tamaño mínimo recomendado según la clasificación de temperatura, la corriente esperada, la cantidad de cables y el tipo de conexión. Este artículo describirá la función de la calculadora.

Choosing an appropriate lead wire for a new stator winding is an important task. The manufacturer’s information is not always available, or the number of circuits or external connection may have been changed, requiring a redesign of the lead wire.  

Before rewinding a stator, EASA strongly recommends winding data verification. We see many cases where failure to invest a few minutes up front costs a service center an additional rewind. One of the most common winding data changes made by service centers is a wire size change. Minimizing the manual calculations associated with this change can increase process efficiency while reducing errors.

Although aluminum magnet wire theoretically can be converted to copper magnet wire of about 5/8 of the original wire area, in some cases this is not advisable. In others, it may result in a change in the magnetic strength of a coil or winding. In this article we will address the most common aluminum-to-copper magnet wire conversions as well as how to deal with whether the wire area should be reduced. Topics discussed include:

• AC motor windings
• Shunt fields
• Series fields and interpoles
• Transformer windings

There are many transformers in use rated up to 10 MVA (10,000 kVA) that were originally wound using aluminum conductors. When damaged or when selected for rewind, the aluminum conductor is often replaced with copper conductor. This is usually fairly routine when the conductor changes are undertaken within the bounds of the original transformer design. It is this type of change that will be reviewed in this article. It is not the intent to provide information here for the complete redesign of the transformer. It is important that all coil dimensions remain as close to the originals as possible. In carrying out the type of change outlined above, there are some design issues and differences in material properties that must be considered before proceeding with the work. Some of these issues are:

• The effect that the difference in thermal characteristics of the materials will have on short term overload capability.
• The effect that the different material properties will have on the original blocking and bracing system.
• The effect that the difference in conductivity will have on conductor size.
• The effect that the difference in conductor size may have on coil resistance and reactance.
• The effect that the different conductor size may have on coil size (axial length) and hence its ability to withstand short circuits.