Carick “Joe” Howard
Red Stick Armature Works, Inc.

Es bien conocido por aquellos que trabajan con el almacenamiento de motores eléctricos que las filosofías y procedimientos de mantenimiento varían. La revisión minuciosa de la información de EASA y siete fabricantes de motores diferentes sobre el almacenamiento de motores reveló algunas diferencias y similitudes interesantes en la información disponible en cada una de las fuentes consultadas.

Varias fuentes comparten elementos comunes como el ambiente, la protección contra humedad, el mantenimiento de los rodamientos y la resistencia de aislamiento. Aquí, la finalidad de nuestro debate es describir algunas de las diferencias y ojalá dar a conocer algunos puntos a tener en cuenta cuando se crea un procedimiento de almacenamiento a largo plazo para los usuarios finales.

Electric motor repair report form to collect basic motor, bearing, shaft, coupling information.

Cyndi Nyberg
Former EASA Technical Support Specialist

Electric motors often use space heaters to prevent condensation inside the motor when it is not running. In damp areas, they may be necessary to prevent condensation from forming on the windings. They are also important for motors that are on “stand-by” equipment, or motors that are out of service for prolonged periods of time. The function of a space heater is to keep the winding temperature 5^o to 10^oC above the ambient temperature.

Another type of space heater is the silicone rubber space heater that is applied directly to the winding end turns. One advantage to this type is that they use less power to heat the windings, and they also remain cool to the touch. It is a good idea to insulate between the heater and the winding. It is possible, although rare, for a faulty heater to cause winding failure.

This version of Principles of Medium & Large AC Motors manual is now available to address applicable IEC standards and practices. This 360-page manual was developed by industry experts in Europe along with EASA's engineering team. (The "original" version of this book based on NEMA standards remains available as a separate document.)

This manual includes drawings, photos and extensive text and documentation on AC motors, including how they work, information on enclosures, construction on components and applications. Many of the principles included apply to all AC motors, especially those with accessories that are associated with larger machines in the past (such as encoders, RTDs, thermostats, space heaters and vibration sensors).

While the manual covers horizontal and vertical squirrel-cage induction motors in the 37 to 3,700 kW (300 to 5,000 hp) range, low- and medium-voltage, most of the principles covered apply to other sizes as well. 

This valuable instructional/resource manual is available in printed and downloadable versions, and focuses primarily on IEC motors.

Sections in the manual include:
(Download the PDF below for the complete Tables of Contents)

• Motor nomenclature & definitions
• Motor enclosures
• Typical motor applications
• Safety & handling considerations
• Basic motor theory
• Motor standards
• Stators
• Squirrel cage rotors
• Shafts
• Bearings & lubrication
• Motor accessories & terminal boxes
• Test & inspection procedures
• Motor alignment, vibration & noise
• Storage procedures
• Synchronous machines

BUY A COPY FOR YOUR OFFICE

PRINTED BOOK DOWNLOADABLE PDF

This book is also available focusing on NEMA Standards — in both English and Español.

NEMA - English NEMA - Español

Jim Bryan
Especialista de Soporte Técnico de EASA (retired)

De vez en cuando, aparece el  tema de los sistemas de calefacción, para solucionar un problema causado por la condensación en los motores (o generadores), que se encuentran fuera de servicio. Son muchos los que piensan que el motor puede sufrir más daños estando inactivo que en operación. Esto es especialmente cierto, cuando existen ambientes húmedos en los cuales la condensación puede causar un impacto negativo sobre los materiales aislantes del bobinado y en sus superficies mecanizadas.

La condensación se forma cuando la temperatura desciende por debajo del punto de rocío.

Este término meteorológico, se refiere a la cantidad de vapor de agua que  el aire puede retener. Entre más alta sea la  humedad, más cerca estará la temperatura ambiente del punto de rocío. Esto se convierte en un problema de condensación, cuando el aire húmedo caliente se enfría, especialmente cuando cae la noche.

Jim Bryan
EASA Technical Support Specialist (retired)

From time to time, the subject of space heating comes up to address issues caused by condensation in idle motors (or generators). Many feel that a motor can receive more harm from being idle than if it is in service. This is especially true in humid environ­ments where condensation can have a negative impact on winding insulation material and machined surfaces. 

Condensation forms when the temperature falls below the dew point. This meteorological term refers to the amount of water vapor the air can hold. The higher the humidity, the closer the ambient temperature will be to the dew point. This becomes a condensation problem when warm, moist air cools, especially at nightfall.