Revised September 2022!
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When we consider putting a machine into service, we must consider the duty rating of the machine. If we do not, there is a good chance that the machine being placed into service will have thermal degradation of the windings. Not every application is created equal.

Cuando consideremos la puesta en servicio de una máquina, debemos tener en cuenta su tipo de servicio. Si no lo hacemos, es muy probable que la máquina sufra una degradación térmica de los devanados. Sin embargo, no todas las aplicaciones son iguales. 

Customers sometimes send in a motor with no nameplate, or an illegible nameplate, having little knowledge of the machine’s ratings. This article will explore the process of evaluating the machine using frame size, winding data and test data to assign reasonable ratings.

Customers will often send in a motor with no nameplate and having little knowledge of the machine’s ratings. This webinar guides attendees through the process of evaluating the machine using core size, winding data and diagnostic testing to assign reasonable ratings.

This manual covers horizontal and vertical squirrel-cage induction motors in the 300 to 5,000 horsepower range, low- and medium-voltage. Most of the principles covered apply to other sizes as well. This manual focuses primarily on IEC motors and standards.

Las versiones impresas y en forma de descarga del valioso manual didáctico / recurso de EASA, “Principios de Motores C.A. Medianos y Grandes”, se  ahora disponibles en inglés y en español. El manual incluye gráficos e ilustraciones, fotografías y mucha información técnica sobre máquinas C.A., incluyendo como funcionan, información específica sobre los tipos de encerramientos, fabricación de componentes y aplicaciones.  Muchos de los principios incluidos en el libro aplican a todos los motores C.A., especialmente a aquellos accesorios que fueron asociados en el pasado con las máquinas más grandes (como encoders, RTDs, termostatos, calentadores de espacio, sensores de vibración, etc.).

Whether you're selecting a motor for a new application or a replacement for one that has failed, you need a reliable way to match the capabilities and performance characteristics of various motors with the requirements of the application.

The nameplate of an electric motor reveals much valuable information about the capability and performance of the machine.

La placa de datos de un motor eléctrico revela mucha información valiosa acerca de la capacidad y desempeño de la máquina.

When a customer calls and wants to replace his diesel or gasoline engine with an electric motor to drive a piece of machinery, it’s easy to assume that “horsepower is horsepower.” Not so fast! It turns out that there are many different ways to measure power.

Cuando un cliente llama y quiere reemplazar su motor diesel o de gasolina por un motor eléctrico para impulsar una pieza de maquinaria, es fácil asumir que “los caballos de potencia son caballos de potencia”. ¡No tan rápido! Resulta que existen muchas formas diferentes para medir la potencia.

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. 

Too often, replacement specifications for three-phase squirrel-cage induction motors cover only basic nameplate data such as power, speed, voltage, and frame size, while overlooking other important performance characteristics such as the design letter. This can lead to misapplication of a motor, causing poor performance, inoperability, or failures that result in unnecessary downtime.

Process downtime is expensive—even more so when it’s unexpected. So, when an electric motor fails, we tend to pull, repair, or replace it, and move on as quickly as possible. In doing so, however, we may miss an opportunity to capture basic information that could help improve the reliability of the application. With a little planning, these data can be gathered with no delay in startup.

Manufacturers deploy various external connection schemes to produce three-phase induction motors for multiple voltages and/or starting methods. Be sure to follow the relevant connection diagram, which is usually affixed to the motor or contained in its manual. If the diagram is lost, damaged, or ignored, you could find yourself dealing with a costly rewind.

This 40-page booklet provides a great marketing tool for your service center! Use it to provide end users with information that will help them obtain the longest, most efficient and cost-effective operation from general and definite purpose electric motors.

This manual, a companion to EASA's 2-day seminar of the same name, covers horizontal and vertical squirrel-cage induction motors in the 300 to 5,000 horsepower range, low- and medium-voltage. Most of the principles covered apply to other sizes as well. This manual focuses primarily on NEMA motors.

Correct interpretation of five operating parameters for NEMA, IEC induction motors When someone reads an electric motor nameplate, the normal assumption is that the information can be used at face value. That applies to some but not all of the nameplate information. For example, the power rating (hp or kW) and frame size are specific to the motor. However, ratings such as voltage, frequency, current, speed (rpm) and efficiency have tolerances associated with them. Our focus in this article will be to discuss the correct interpretation of each of these five operating parameters for induction motors of both NEMA and IEC design. Topics discussed include: Voltage and frequency - NEMA MG1-12.44 and IEC 60034-1.7.3 Current - NEMA MG1-12.47 and IEC 60034-1 Speed (rpm) - NEMA MG1-12.46 and IEC 60034-1-12.1 Efficiency - NEMA MG1-12.58 and IEC 60034-1 Note: The letter codes for insulation class, design and kVA code that appear on NEMA motor nameplates are addressed in "Motor Nameplate Letter Code Designations" in the March 2009 issue of Currents.

This presentation stresses the importance of taking accurate winding data and explains and emphasizes the consequences of inaccurate data.

Steps to determine characteristics needed for finding a replacement A motor is received from a customer with the request that it be replaced. However, it does not have a nameplate. The steps to determine the motor characteristics needed for identifying a replacement will be described here. These same steps can also be used in the case of repair of a motor without a nameplate, so that a new nameplate with key identification characteristics can be made and attached to the repaired motor. The focus of this article will be NEMA or IEC horizontal motors in standard frame sizes.

Motors built to National Electrical Manufacturers Association (NEMA) standards use alphabetical letter codes on the nameplate to designate a number of alternating current (AC) motor characteristics. These characteristics are the code, design, and insulation class. Read the nameplate carefully as these designations are easily misinterpreted. Similarly, re-confirm these data items when your customer provides them. For example, the letter "B" could designate a design code, insulation class or kVA code (though highly improbable.) What do these different designations mean?

When taking winding data, equalizer connections can be mistaken for wye points. You may wonder what purpose equalizer connections serve and whether they can just be eliminated to simplify the repair process. Before discussing equalizers, we will explore the factors that lead to a need for equalizers.

This article introduces a set of procedures for identifying unmarked leads of 6-lead motors with 1 or 2 windings. For most connections, the only tools required for these procedures are an ohmmeter and surge tester. These procedures will also help identify the type of connection when there is no nameplate present.

If you have ever tried to figure out the field resistance from the information on a DC motor nameplate, you probably wonder what in the heck the manufacturer was thinking! You know Ohms Law, but the nameplate information just doesn't seem to follow it. For those accustomed to the format of the AC motor nameplate, DC nameplate information can seem confusing - even misleading. Misinterpret the field voltage/field current/rpm information, and a technician is liable to conclude that something is wrong with the motor. A customer may even question whether a repair was done correctly.