Presented by Matthew Conville, P.E.
EASA Technical Support Specialist

This webinar goes through the basics of what accessories may be needed for proper VFD control and power quality add-ons to improve motor driven system reliability. Just buying and installing a VFD isn’t enough to ensure proper operation of a motor driven system in its application, nor does it protect upstream and downstream devices from power quality issues. Topics include:

• Drive accessories
  • Operator panels, encoders, position encoders, communication devices
• Power quality accessories
  • VFD cables and EMC terminations
  • Input reactors and/or isolation transformers
  • Output filters (reactors, dV/dt, sinusoidal, inductive chokes, etc)
• Impacts on AC motors
  • Reduction in SF
  • Winding failures
  • Shaft voltage/bearing currents
  • Turn down ratios

This presentation will be useful for anyone new to VFD applications, or anyone in need of a refresher course. 

Gary Braun
Brehob Corporation

If you’ve ever applied variable frequency drives (VFDs) to standard motors, I’m sure you know how critical it is to understand the specific application and to get all the required data so that you can apply the drive properly. It’s not the time to guess or make assumptions. Most failed applications are a result of not getting all the information. 

When trying to apply VFDs to old or existing cranes and hoists, this holds doubly true. Several drive manufacturers sell their crane and hoist drives only through authorized “crane and hoist” dealers because the applications are fraught with potential problems. Before beginning one of these projects, make sure your insurance carrier covers you for the redesign and work on cranes and hoists.

Presented by Matthew Conville, MBA, PE

Variable frequency drives (VFDs) are more common than ever before.  Sometimes when a VFD is introduced into a motor driven system, system reliability suffers. This recording addresses some of the common factors that reduce motor driven system reliability and how to correct them.

• Common failures in VFD motor driven systems
• How these failures can be corrected
• Questions to ask to before implementing a VFD to maintain system reliability

This recording is intended for inside sales, outside sales, sales managers, engineering, and field service technicians. 

Bill Colton
Baldor Electric Co.
Commerce, California
Technical Services Committee Member

When selecting a drive for an ap­plication, there are many technical and commercial issues to explore in arriving at a choice. The scope of this article is to consider some of the techni­cal issues involved.

Let us assume that the motor is already in place and the customer has asked you to help select an adjustable speed drive. You have determined that the application is “constant torque.” (Constant torque is the same amount of full load RMS [root mean square] torque over the entire speed range required by the application.) 

By Mike Howell
EASA Technical Support Specialist

Motors that meet the requirements of NEMA: MG1 Part 31 are designed for use with variable-frequency drives (VFDs). Motors that meet the requirements of NEMA: MG1 Part 30 may be suitable for inverter duty if appropriate measures are taken such as line conditioning. End users desiring speed and/or torque control often procure and install VFDs to modify existing applications where a standard-induction motor is in place. Frequently, they try to control costs by using the existing motor. There are a few areas of concern involving misapplication of a standard induction motor.

Topics covered include:

• Speed-torque characteristics
• Shaft currents
• Installation

READ THE ARTICLE

REVISED September 2022!

The EASA Technical Manual, containing more than 900 pages of information specific to electric motor service centers, is available FREE to EASA members as downloadable PDFs of the entire manual or individual sections. The printed version is also available for purchase. Each of the 13 sections features a detailed table of contents.

VIEW, DOWNLOAD OR PURCHASE

7 presentations

$35 for EASA members

 

A special discounted collection of 7 webinar recordings focusing on various aspects of electromechanical repair.

Once purchased, all 7 recordings will be available on your "Downloadable products purchased" page in your online account.

Downloadable recordings in this bundle include:

Time-Saving Repair Tips
Presented August 2014

This webinar shares:

• The secrets used by other service centers to gain a competitive edge in the repair process.
• Mechanical, winding and machining tips reduce repair time, help avoid unnecessary rework, and decrease turn-around time.

Target audience: Supervisors, machinists, mechanics, winders, and sales personnel who interact with the end user.

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Repair Best Practices to Maintain Motor Efficiency
Presented June 2012

There are certain repair processes, such as winding removal and replacement, that can impact the efficiency and reliability of electric motors. Prudent repair practices must not increase overall losses, and preferably should maintain or reduce them.

This presentation explains how those repair processes affect efficiency and reliability, and gives the best repair practices in order to maintain or improve efficiency.

Target audience: This presentation is most useful for service center inside and outside sales representatives, customer service personnel, engineers, supervisors and managers. The content will be beneficial for beginners through highly experienced persons.

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Practical Problem Solving for the Entire Service Center
Presented August 2013

This presentation focuses on a report format developed by Toyota for a simple, yet methodical approach to document improvement. Whether you're dealing with problems related to sales, purchasing, repair or testing, if all team members can learn to speak the same, simple problem-solving language, they can tackle problems efficiently and effectively.

Target audience: This presentation is best suited for executives, managers, team leaders and front line supervisors from the office and service center who want to understand and implement such a program.

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Induction Motor Speed Control Basics
Presented March 2019

Induction motors are most often applied to what are essentially constant speed drive applications. However, the use of induction motors in variable speed applications continues to grow, primarily due to technology advances in power electronics. This webinar will review speed control basics for induction machines.

• Wound-rotor motor speed control
• Squirrel-cage speed control by pole changing
• Squirrel-cage motor speed control by variable voltage, fixed frequency
• Squirrel-cage speed control by variable voltage, variable frequency

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AC Motor Assembly and Testing
Presented August 2018

This webinar recording focuses on:

• Motor assembly issues
• Electrical and mechanical inspection
• Static and run testing
• AC motors with ball, roller and sleeve bearings

Target audience: This webinar recording is most useful for service center mechanics, supervisors and engineers. The content will also be beneficial for machinists, managers and owners.

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On-Site Testing & Inspection of Electric Motors
Presented July 2015

This webinar covers electrical testing and inspection of installed electric motors, including:

• Condition assessment for continued service
• Diagnostic fault testing and interpretation
• Physical inspection key points

 

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Selecting Replacement DC and 3-Phase Squirrel Cage Motors
Presented September 2019

On many occasions, a different motor type is desired or needed. In these cases it is essential that the replacement motor provides the required performance, and do so reliably.

This presentation focuses primarily on the electrical aspects of selecting replacement motors. It also addresses speed and torque considerations.

• DC motor to DC motor
• DC motor to 3-phase squirrel cage motor
• AC motor to 3-phase squirrel cage motor

Target audience: Anyone involved with selecting replacement motors or diagnosing issues with replacement motor installations.

Kevin J. Miller 
Apparatus Repair & Engineering, Inc. 
Hagerstown, Maryland 
Technical Education Committee Member 

Motor sophistication, precise torque and speed control and accuracy are all common­place in the manufacturing environment today. They are not just reserved for the aerospace or machine tool industry. 

With modern processes in manufacturing we need to know and control the speed, position and velocity of electric motors. With this precision comes the need for feedback in these areas. 

Servo, closed loop vector, brushless DC, standard DC mo­tors and standard three-phase AC motors use feedback devices such as encoders and resolvers. Many AC and DC motors have the feedback device mounted on the exterior of the opposite drive endbell, mechanically attached to the rotating shaft. Servo, vector and brushless DC motors usually have an encoder or resolver mounted inside the endbell as an integral part of the equipment. 

Rob Boteler
Confluence Energy LLC

On October 22, the European Commission submitted its plan to expand motor and power converter efficiency regulations. As part of the EcoDesign directive, the Commission has been working on expanded motor and drive regulations for several years. The European Union directive will address both motors and variable frequency drives (VFDs) from .75 to 1,000 kW (1 to 1340 hp).

Efficiency directives in Europe are drafted by the Commission with individual countries responsible for enforcement. Unlike the USA where the regulation is promulgated and enforced at the federal level through the Department of Energy, each country within the EU has enforcement responsibility. Though some complain that the DOE rule making process is very lengthy and stressful, it does provide all interested parties with an opportunity to be heard. The EU Commission also has a process for the development of regulations, and many would argue that the manufacturers are somewhat less of an integral part of the EU process.  

The directive that will cover the new EU motor and power converter regulations is referred to as the “annex EN.” It has yet to receive its reference number. EC640/209, the current directive, will be replaced. 

Covered motor products
Beginning January 15, 2021, the energy efficiency of three-phase motors with a rated output equal to or above 0.75 kW (1 hp), and equal to or below 1,000 kW (1340 hp), with 2, 4 or 6 poles, which are not brake motors, increased safety motors, or other explosion-protected motors, shall correspond to at least the IE3 efficiency level. This should align with NEMA Premium 50 Hz.

Beginning July 1, 2022, the energy efficiency of three-phase motors with a rated output equal to or above 0.12 kW (0.16 hp) and below 0.75 kW (1 hp), single-phase motors with a rated output equal to or above 0.12 kW (0.16 hp), and increased safety motors with a rated output equal to or above 0.12 kW (0.16 hp) and equal to or below 1,000 kW (1,340 kW) shall correspond to at least the IE2 efficiency level.

Also, the energy efficiency of three-phase motors with a rated output equal to or above 0.75 kW (1 hp) and equal to or below 1,000 kW (1,340 hp) with 2, 4, 6 or 8 poles, that are not increased safety motors, shall correspond to at least the IE3 efficiency level. 

The directive includes AC motors that NEMA would describe as special or definite purpose, making this new regulation quite broad in the range of covered products. The EU directive does include motors that cannot be tested with the addition of a temporary endshield. 

The directive will not include air over (AO), totally encloseTENV, high ambient (60° C), high altitude (4,000 meters [13,000 feet]), low ambient (-40° C) and maximum operating temperature (400° C). Additionally, the directive exempts integral brake motors and integral motors and controls (IMACs). 

The directive does not include technologies other than AC. However, it is not clear if there is any distinction within the single-phase designs (cap start cap run, cap star induction run, etc.).

Covered variable speed drives 
The regulation covers variable speed drives with three phases input that are rated for operating with one motor within the 0.75 kW – 1,000 kW (1 to 1340 hp) motor rated output range, have a rated voltage above 100 V and up to and including 1,000 V AC, and have only one AC voltage output.

Variable speed drive (VSD) means an electronic power converter that continuously adapts the electrical power supplied to the motor to control the motor’s mechanical power output according to the torque-speed characteristic of the load driven by the motor, by adjusting the power supply to a variable frequency and voltage supplied to the motor. 

Product information requirements for motors 
According to the regulation, the product information requirements below shall be visibly displayed on the technical data sheet or user manual supplied with the motor; the technical documentation for the purposes of conformity assessment pursuant to Article 5; on websites of the manufacturer of the motor, its authorized representative, or the importer; and the technical data sheet or user manual supplied with products in which the motor is incorporated.

The exact wording used in the following list does not need to be repeated. The information may be displayed using clearly understandable graphs, figures or symbols rather than text: 

• Rated efficiency (ηN) at the full, 75% and 50% rated load and voltage (UN), determined based on the 50 Hz operation and 25° C ambient reference temperature
• Efficiency level: “IE2,” “IE3,” “IE4” or “IE5,” as determined as specified in the first section of this annex, followed by the term “-motor” 
• Manufacturer’s name or trade mark, commercial registration number and address
• Product’s model identifier
• Number of poles of the motor
• The rated power output(s) PN or range of rated power output (kW)
• The rated input frequency(s) of the motor (Hz)
• The rated voltage(s) or range of rated voltage (V)
• The rated speed(s) or range of rated speed (rpm) 
• Whether single-phase or three-phase
• Information on the range of operating conditions for which the motor is designed: 
  • altitudes above sea-level
  • minimum and maximum ambient air temperatures including for motors with air cooling
  • water coolant temperature at the inlet to the product, where applicable 
  • maximum operating temperature
  • potentially explosive atmospheres
• Information relevant for disassembly recycling or disposal at end-of-life; 
• If the motor is considered exempt from efficiency requirements in accordance with Article 4(2) of this Regulation: the specific reason why it is considered exempt. 

For motors exempt from the efficiency requirements in accordance with Article 4(2)(m) of this regulation, the motor or its packaging and the documentation must clearly indicate, “Motor to be used exclusively as spare part for” and the product(s) for which it is intended.

Efficiency requirements for variable speed drives 
Efficiency requirements for variable speed drives shall apply as follows: the power losses of variable speed drives rated for operating with motors with a rated output equal to or above 0.75 kW (1 hp) and equal to or below 1,000 kW (1,340 hp) shall not exceed the maximum power losses corresponding to the IE2 efficiency level.

Conclusions
This is the first regulation for VSD efficiency. Overall, the directive maintains references to IEC standards for both motors and VSDs that have been developed in collaboration with industry, regulators and energy advocates. Test methods will use IEC 60034, which delivers results similar to IEEE 112 or CSA 390.

The regulation in its entirety may be found at https://bit.ly/2PG0VaD.

The efficiency levels also reference IEC levels IE2 and IE3. Note that the directive includes a reference to IE4 and IE5 levels, which are not scheduled for implementation. Unlike NEMA, IEC has one efficiency table regardless of enclosure type calculated at 1.0 SF. 

One issue that will face motor manufacturers is the smaller size of IEC motors to power ratio. In some cases, this will force motors to jump one frame size. End-users and OEMs buying these higher efficiency motors will need to be cognizant of possible changes to the motor’s size that may cause form, fit and function issues in a specific application.

Tom Bishop, P.E.
EASA Senior Technical Support Specialist

An old saying claims: “If it’s in black and white, it must be right.” Seeing something in writing makes it more believable than the spoken word. However, that does not mean it is true. We should always look for substantiation to back up statements, whether written or verbal.

A more recent saying is: “If it’s on the Internet, it must be true.” Apply that same fact-check here. Look for substantiation before accepting information gleaned from the Internet.  

Here is a random collection of some relatively common misconceptions about three-phase squirrel cage motor performance characteristics.

Chuck Yung
Especialista Sénior de Soporte Técnico de EASA 

Todos nosotros tenemos ese cliente ocasional que compró “una ganga” en una subasta, como un compresor, un torno o una máquina para trabajar madera y que solo descubre al comenzar a instalarlo que ese equipo tenía un motor trifásico y que él dispone únicamente de energía monofásica. Posiblemente sea su vecino o un amigo de la iglesia. En cualquier caso, usted está a punto de ser contactado para “convertir” esa parte del equipo y probablemente piensa que eso le va a costar más de lo que el puede gastar.

Presented by Sarah Widder and Nate Baker
Cadeo

As COVID-19 and its physical and economic impacts reshape new and existing industrial and commercial systems, operators are looking at how to most efficiently run existing commercial and industrial spaces that may be used very differently in the future.

While adding variable speed capability in commercial buildings is not a new idea, a new analysis confirms major energy and cost savings is available by pairing those products with a power drive system (PDS) – regardless of a pump’s load variability. A PDS combines an electric motor, adjustable speed controls and sensors that provide feedback to the equipment, allowing the equipment to slow down or speed up to meet current demand. This idea and the added flexibility a PDS can provide may be even more important as we move forward in uncertain times.

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Speaker Bios
Sarah Widder
Sarah Widder is currently a director at Cadeo, an energy efficiency consulting firm that works with utilities, non-profits, industry and regulatory agencies to promote adoption of energy-saving technologies and practices in the marketplace.  In her current role, Sarah has been working with the Northwest Energy Efficiency Alliance and other trade associations to develop market transformation programs for motor driven equipment under NEEA’s Extended Motor Products (XMP) Initiative.  Sarah started working on motor-driven technology in her previous job at Pacific Northwest National Laboratory, where she supported test procedure development for the U.S. Department of Energy (DOE) and led development of a new test procedure and efficiency metric for pumps, the Pump Energy Index (PEI).  Sarah has a B.S. in Chemical Engineering from the University of Washington and a PhD in Civil Engineering from Washington State University.    

Nate Baker
As a senior associate and member of Cadeo's engineering team, Nate Baker leverages his background in industrial facilities to support energy efficiency program design and regulatory review. Most recently, his work has focused on supporting efforts to increase energy efficiency in motor-driven equipment and adoption of energy efficient technology in commercial and industrial applications broadly. His research has supported program development by establishing unit energy savings estimates for pumps and fans and documenting operational characteristics of clean water pumps. Nate also provides technical expertise to support the development of energy conservation standards and test procedures.

By Chuck Yung
EASA Senior Technical Support Specialist

There are several methods to operating a three-phase motor using single-phase power to make what would be an otherwise expensive and arduous process a little easier.

So, you told a neighbor you work with electrical equipment and now he thinks you can solve his problem because he or she bought a three-phase motor that can't run on single-phase power. Being asked to convert this motor already sounds like more trouble than it's worth. That's not quite true though. There are some methods to make the process easier.

These methods include:

• The phantom leg method
• Rotary phase converter method
• Variable frequency drive method

READ THE FULL ARTICLE

Pat Douglas Kirby Risk
Mechanical Solutions & Service

Shaft currents have always been a concern for large motors due to magnetic asymmetries within the motor. Manufacturers strive to keep these to a minimum.

With the widespread use of Variable Frequency Drives (VFDs), shaft current issues have become a concern in all sizes of motors. If these currents are discharged through the bearings, electrical discharge machining (EDM) occurs. Proper installation of VFDs can play a large part in mitigating issues with shaft currents. 

Many end users are not aware of shaft currents or their destructive paths. All too often they think that the motor bearings keep failing because the motor repair was not completed properly. 
Service centers need to be on the lookout for these issues when repairing a customer’s equipment. Many repairs arrive at the service center with no history and no hint of what the problem with the motor might be. The technicians have to do an “autopsy” of the motor to be sure the causal problem is repaired and not just the symptom.

Art Godfrey (retired)
Birclar Electric & Electronics
Romulus, Michigan

Introduction
Modern variable frequency drives (VFDs) offer an almost dizzying range of capabilities that include output fre­quencies into the hundreds of hertz. It can be tempting to use a standard AC induction motor with one of these VFDs. But doing so requires a thorough understanding of the intended applica­tion and how the VFD will affect the motor. Since the most popular VFDs sold today are pulse-width modulated (PWM) type, the comments and recom­mendations in this article will assume that is the type used.  Also, motor volt­age will be 600 volts or less.

Mike Howell
EASA Technical Support Specialist

Induction motors are most often applied to what are essentially constant speed drive applications. However, the use of induction motors in variable speed applications continues to grow, primarily due to technology advances in power electronics. This webinar will review speed control basics for induction machines.

• Wound-rotor motor speed control
• Squirrel-cage speed control by pole changing
• Squirrel-cage motor speed control by variable voltage, fixed frequency
• Squirrel-cage speed control by variable voltage, variable frequency

Tom Bishop, P.E.
EASA Senior Technical Support Specialist

This webinar recording reviews the failures associated with 3-phase motors on Variable Frequency Drives (VFDs) and how to rewind to limit future failures. The transient over-voltages produced by the VFD can cause the winding insulation to break down. Motor manufacturers and service centers have recognized that the winding insulation system must be enhanced to help withstand the effects of being used on a VFD. Topics include:

• Brief overview of the transient voltage phenomena
• Materials for an inverter-duty winding system
• Processes for an inverter-duty winding system
• Other considerations: cables, VFDs

This webinar is intended for winders, shop supervisors and engineering staff.

Presented by Matthew Conville, MBA, PE
EASA Technical Support Specialist

This webinar recording explains the basics of low voltage AC drive types and control methods. As VFDs and their applications have become more complex, it can be difficult to determine what type of VFD will be required for an application and how the motor needs to be controlled. Topics covered include:

• Types of Drives
  • Single Quadrant, SQ with Braking, Regenerative and Active Front End
• Types of Control
  • V/Hz (Scalar), Vector Sensorless (Open Loop Vector), Vector (Close Loop Vector)
• VFD Selection for Application

Target audience: Anyone new to VFD applications, or anyone in need of a refresher course.

Matthew Conville, MBA, PE
EASA Technical Support Specialist

In today’s global economy, it is quite possible to get electric motors from all over the world. This gives us plenty of options to choose from when selecting an electric motor. Most electric motors that are 500 hp (373 kW) or less will conform to one of two basic manufacturing standards; NEMA or IEC. Both have specific clauses which define the voltage stress limits an induction machine can be subjected to in its application, which is powered by Variable Frequency Drives (VFDs)/converters. The intent of this article is to focus on IEC standards for managing voltage stress in VFD applications as it pertains to the motor’s windings. If more detail is needed on NEMA applications, please refer to NEMA MG-1 Part 31.

Matthew Conville, MBA, PE
Especialista de Soporte Técnico de EASA

En la economía global actual, es posible adquirir motores eléctricos fabricados en todo el mundo. Esto nos ofrece muchas opciones para seleccionar un motor eléctrico. La mayoría de los motores eléctricos de 500 HP (373 kW) o menos se ajustarán a una de las dos normas básicas de fabricación; NEMA o IEC. Ambas normas tienen cláusulas específicas que definen los límites de sobretensión a la que se pueden someter las máquinas de inducción en aplicaciones que funcionan con variadores de frecuencia (VFD)/ convertidores. La intención de este artículo es centrarse en las normas IEC para gestionar la sobre tensión en aplicaciones con VFD en lo que respecta a los devanados del motor. Si se necesitan más detalles sobre las aplicaciones NEMA, consulte NEMA MG-1 Parte 31.

Rick Hoadley
ABB

Whenever an application engineer is planning on installing adjustable speed drives for AC motors, line current harmonics and reflected waves are two factors that need to be addressed. Four basic questions should be answered in order to successfully commission the drive system:

1. What is my power system like today
2. What impact will the additional drives have on the power quality for the other equipment
3. If needed, what harmonics mitigation method should be used
4. How long and what type of cable is used between the drive and motor

This paper, presented at the 2013 EASA Convention, deals with understanding IEEE Std 519 and various mitigation methods in order to meet those recommendations. It also reviews the types of filtering that is available to reduce the reflected waves seen at the motor terminals.

Topics covered include:

• Overview of drives topologies
• The differences between 6,12,18 pulse and active front end drives
• How the differences in drives relate to harmonics generated
• Filters on either end of the drive to mitigate the effects of harmonics, as well as voltage spikes and other potential damaging effects on the motor

Rick Hoadley
ABB, Inc.
New Berlin, WI

Whenever an application engineer is planning on installing adjustable speed drives for AC motors, line current harmonics and reflected waves are two factors that need to be addressed. Four basic questions should be answered in order to successfully commission the drive system:

1. What is my power system like today
2. What impact will the additional drive(s) have on the power quality for the other equipment
3. If needed, what harmonics mitigation method should be used
4. How long and what type of cable is used between the drive and motor

This paper, originally presented at the 2014 EASA convention, deals with understanding IEEE Std 519 and various mitigation methods in order to meet those recommendations. It also reviews the types of filtering that is available to reduce the reflected waves, first turn insulation stress, and common mode voltages seen at the motor terminals.

• Overview of drives topologies
• The differences between 6,12,18 pulse and active front end drives
• How the differences in drives relate to harmonics generated
• Filters on either end of the drive to mitigate the effects of harmonics, as well as voltage spikes and other potential damaging effects on the motor

Tom Bishop, P.E.
Especialista Sénior de Soporte Técnico de EASA

Un viejo dicho dice: “Si está en blanco y negro debe estar bien”. Ver algo por escrito lo hace más creíble que si se escucha verbalmente. Sin embargo, eso no significa que sea verdad. Siempre deberíamos buscar una justificación que soporte un testimonio, sea escrito o verbal.

Un dicho más reciente dice: “Si está en internet debe ser cierto”. Aplique el mismo concepto aquí. Busque una justificación antes de aceptar información obtenida por internet. Aquí tenemos una colección de algunos de los conceptos errados más comunes acerca de las características de desempeño de los motores eléctricos tipo jaula.

Richard Hughes (deceased)
Pump & Motor Works, Inc.

This series of four articles covers many schemes of motor protection and control.

Topics covered include:

• Time delay fuses
  • Fuse selection
  • Over-current protection
  • Avoiding fuse overloads
• Circuit breakers
  • Inputs to electronic protection relays
  • Feeding, protecting a motor starter
  • Common features
• Motor starters
  • How motor starters operate
  • Light, medium or heavy duty
  • Momentary start button
  • Wye series start, parralel run
  • Variety of controls
• IEEE and ANSI power system device numbers
• Dashpot type overload relay
• Thermal overload relay
• Current transformer
• Compact relays
• Restoring balanced voltage
• Transient voltages
• Surge capacitor, surge arrestor

Chuck Yung
EASA Senior Technical Support Specialist

We all have that occasional customer who got a “deal” at an auction: a compressor, or lathe, or wood-working equipment, only to discover when he started to install it that this equipment has a three-phase motor and only single-phase power is available. Maybe it’s your neighbor or a friend from church. In any case, you know that you are about to be called upon to “convert” that piece of equipment, and you probably realize that it’s going to cost you more than you can charge.

Ian Culbert (deceased)
Iris Power-Qualitrol

Editor’s Note:  The following article was written by Ian Culbert, an engineer with Iris Power - Qualitrol in Mississauga, Ontario, Canada. It was submitted for publication by John Letal of Iris Power - Qualitrol and member of EASA’s Technical Services Committee. Sadly, Mr. Culbert passed away recently. We appreciate his contributions to the industry. 

Introduction
Due to their ever decreasing costs, variable frequency drives (VFDs) are becoming more popular for energy conservation and the reduction in inrush currents during motor starting. The most widely used type of drive today is a voltage-source, with pulse width modulated (VS-PWM) inverter, since it tends to be less expensive than other possible topologies.

In the past decade, medium and high voltage motors rated 2.4 kV to 13.8 kV fed by VS-PWM drives have become more common. Currently motors rated up to 100 MW are being designed. Motors supplied from such drives have seen premature stator winding failures since the voltage impulses from the drive can lead to rapid insulation system aging. In most cases, as the aging progresses, the partial discharge (PD) activity increases. Thus, there is a desire for on-line PD detection for such motors. 

Unfortunately measurements with conventional electrical PD detectors tend to be masked by 1000-3000 V impulses created by multi-stage VS-PWM drives. The rise time of the voltage impulses from the multi-stage VS-PWM drives tend to be 500 ns or longer. This article describes the technical issues in on-line PD detection on motors fed by VS-PWM drives, and gives an example of one system that detected the PD successfully.

Las versiones impresas y en forma de descarga del valioso manual didáctico / recurso de EASA, “Principios de Motores C.A. Medianos y Grandes”, se encuentran 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.).

Las versiones  forma de descarga ofrecen funciones prácticas ya que contienen toda la información que contiene el manual impreso, pero en formato PDF, fácil de usa, ya que contiene marcadores que permiten a los lectores navegar rápidamente por el documento y “saltar” a la página deseada.

Las secciones del manual incluyen:

• Terminología y Definiciones del Motor
• Tipos de Encerramientos de Motores
• Aplicaciones Típicas para Motores
• Consideraciones de Manejo y Seguridad
• Teoría Básica del Motor
• Normas para Motores
• Estatores
• Rotores de Jaula de Ardilla
• Ejes
• Lubricación y Rodamientos
• Accesorios del motor & Cajas de Conexiones
• Procedimientos de Inspección y Prueba
• Alineamiento del Motor, Vibración y Ruido
• Procedimientos de Almacenamiento
• Máquinas Sincrónicas

COMPRAR

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

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PRINTED BOOK DOWNLOADABLE PDF

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

NEMA - English NEMA - Español

This valuable instructional/resource manual is available in printed, downloadable and CD-ROM versions.

For this second edition, this 320-page manual has been reorganized, updated with new information, including revised standards and published articles, and edited extensively. The manual includes drawings, photos and extensive text and documentation on AC motors, including how they work, specific information on enclosures, construction of components and applications. Many of the principles included apply to all AC motors, especially those with accessories that were associated with larger machines in the past (such as encoders, RTDs, thermostats, space heaters, vibration sensors, etc.).

While the 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 NEMA motors.

Sections in the manual include:

• 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

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BOOK DOWNLOAD CD-ROM BOOK & CD-ROM

This book is also available focusing on IEC Standards ... IEC VERSION

 

Jim McKee (deceased)
Alabama Electric Motor Service

The ability to vary the speed of our prime movers has always been desirable. Electric motors are no exception. Many designs and types of motors have been developed over the years to fill this need for variable speed. The most widely used and successful designs include the direct current motor, eddy current coupling/ motor combination, three-phase shunt commutator motor (brush shifting or Schrage motor), and various mechanically variable devices such as adjustable pitch pulleys and cone/ wheel combinations.

EASA service centers often find it desirable or necessary to replace one of these vintage variable speed devices. There are many reasons for replacing older drives; they include improved efficiency, unavailability of repair parts and high maintenance costs. 

A properly sized Variable Frequency Drive (VFD) /three-phase induction motor combination is often the right choice for the new drive.

Revisit EASA's 2021 Convention & Solutions Expo by buying access to recordings of the general sessions and education events streamed from EASA's website!

These recordings provide just over 22 hours of training. Downloadable PDFs of slides and technical papers are included!

Technical presentations include:

• Overview, Operation, Troubleshooting, Testing & Repair of Synchronous Motors - Javier Portos, Integrated Power Services, LLC, La Porte, TX
• Understanding Corrosion in Pumps - Gene Vogel, EASA Pump & Vibration Specialist
• Tips & Tricks for Submersible Pump Repair - Gene Vogel, EASA Pump & Vibration Specialist
• Proper Field Installation of Vertical Turbine Pump Motors - Gene Vogel, EASA Pump & Vibration Specialist
• Carbon Brush Applications, Tip & Tricks - Matthew Conville, EASA Technical Support Specialist
• Generator Repair Tips - Wayne Hall, Jenkins Electric, Charlotte, NC
• Repair Best Practices to Maintain Motor Efficiency & Reliability - Tom Bishop, P.E., EASA Senior Technical Support Specialist
• Failure Modes, Troubleshooting & Maintenance Best Practices - Calvin Earp & Ron Widup, Shermco Industries, Irving, TX
• Estimating Performance of Small Induction Motors Without a Dyno - Mike Howell, EASA Technical Support Specialist
• Use the Latest Tools of the Trade for Field Testing of Electric Motors - Calvin Earp & Ron Widup, Shermco Industries, Irving, TX

En Español

• Construcción del Estator (de Principios de Motores C.A. Medianos y Grandes) - Carlos Ramirez, EASA Especialista de Soporte Técnico
• Lo Qué Necesita Saber para Comprar, Instalar, Operar & Reparar Motores Eléctricos - Carlos Ramriez, Especialista de Soporte Técnico de EASA

Sales presentations include:

• 5 Fundamentals for a Successful Sales Attack! - Mike Weinberg Speaker, Consultant, Best-Selling Author
• Getting The Meeting - Mike Weinberg Speaker, Consultant, Best-Selling Author
• Every Sales YES Begins with a KNOW - Sam Richter, SBR Worldwide, LLC, Minnetonka, MN

Management presentations include:

• EASA Research on Growing Your Business: Key Info from the Manufacturer/Supplier Community - Jerry Peerbolte, J. Peerbolte & Associates, Fort Smith, AR
• EASA 2021 and Beyond - Brian Beaulieu, ITR Economics, Manchester, NH
• Global Update: Marketplace Trends on Motor-Driven Systems (and IIoT) - Ivan Campos, Analyst, Manufacturing Technology, OMDIA (formerly IHS Markit)
• Engaged Leadership - Clint Swindall, Verbalocity, Inc., San Antonio, TX
• Connecting Generations - Clint Swindall, Verbalocity, Inc., San Antonio, TX
• Optimizing Service Center & Management Efficiency - Chuck Yung, EASA Senior Technical Support Specialist

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How do I access this content?
After purchasing, you can access the streaming content by going to the Convention or Training menus at easa.com and looking for "Past Convention Presentations" ... or you may go to https://easa.com/convention/past-convention-presentations/easa-rewind-2021.

NOTE: Access to the streaming content will be granted only to the person making the purchase.

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Con el aumento de la popularidad de los variadores de frecuencia electrónicos (VFDs o drives), es probable que casi todos los centros de servicio miembros de EASA hayan reparado algún motor que funcione con un variador de frecuencia en las instalaciones de un cliente. Lo más conveniente después de reparar estos motores es probarlos, generalmente en vacio, utilizando un drive. Esto nos permite simular la aplicación real del cliente variando la velocidad así como también tener la certeza que el motor funciona bien mecánicamente dentro de un rango de velocidades. Esto incluye descubrir problemas de vibraciones, identificar alguna velocidad de resonancia dentro del rango de operación y otros problemas. Además, si el motor está trabajando por arriba de la frecuencia de red (ej. 50 ó 60 Hz), deberá funcionar hasta alcanzar su velocidad máxima para comprobar sus niveles de vibración y que los rodamientos puedan expulsar el exceso de lubricación y se asienten por sí mismos en su posición de trabajo (break-in).

Los temas cubiertos incluyen:

• desafíos de selección
• Tensión, potencia y frecuencia
• VFD nuevos o usados para las pruebas?
• Parámetros de operación

Art Godfrey (retired)
Birclar Electric & Electronics
Romulus, Michigan
Technical Services Committee Member

With the growing popularity of variable frequency drives (VFDs), it is likely almost every EASA service center has repaired motors powered by one in a customer’s installation. For these motors, it is best that after repair they are tested using a VFD, typically at no-load. This will provide operation mimicking the actual customer applica­tion, at varying speeds, and will help ensure proper mechanical operation throughout the speed range. This will include detecting vibration problems, identifying any resonant speeds within the operating range, and more. Also, if the motor is used above utility line fre­quency (i.e., 50 Hz or 60 Hz), it should be operated up to top speed for vibra­tion measurement and a good break-in of the bearings.

Presented by Chuck Yung
EASA Senior Technical Support Specialist

This webinar explains what shaft currents are, what causes them, and differentiates between the two common causes:

1. Circulating currents which affect DC motors and AC motors not operating from a drive
2. Shaft currents caused by operation from a VFD, and how to tell the difference between the two.

This webinar also discusses and compares methods to mitigate shaft currents and explains why the different causes of shaft currents require different solutions. It covers:

• Shorted rotor iron
• Uneven air gap
• Unbalanced voltage
• What type of grounding brush works best?
• Role of carrier frequency in causing shaft currents
• How to recognize the problem on site
• Insulation thickness, capacitance, and types of insulated bearings

This information is useful to engineers, service center managers, mechanics and anyone interacting with customers.

Art Godfrey (retired)
Birclar Electric & Electronics

No-load testing of repaired motors is common in most if not all repair service centers. ANSI/EASA AR100-2010 Recommended Practice specifies, “for AC motors, no-load running tests should be made at rated voltage and rated frequency.” For sine-wave powered motors, this statement is straightforward. For motors used on variable frequency drives (VFDs), there are a number of possibilities service centers may employ with the motor supplied by line (utility) power, and in some cases the tests may be less than ideal.

George Stratton 
G.E. Jones Electric Co., Inc. 
Amarillo, Texas 
Technical Education Committee Member 

Before I get started with this rambling about variable frequency drives (VFDs), I wish to ex­plain that this technical article is definitely NOT intended for the “drive techs” out there among you. It is intended to educate that poor, confused soul who might be timid when it comes to dealing with these high tech appliances…just as I once was. I hope that this helps you. 

Is anyone sleepy? Then welcome to VFDs 101! I’ve always said that if anyone has a problem sleeping, just tune in the History Channel. Well, here’s another sure cure. Let’s learn about VFDs! 

Herb Prychodko 
Kentucky Service Co., Inc.

Lexington, Kentucky The advent of Variable Frequency Drives (VFDs) has allowed many applications to take advantage of the increased controllability of AC motors. This has resulted in a large increase in the use of these devices. However, an unwanted consequence of using VFDs is the distortion of the supply’s fundamental sine wave, commonly referred to as line harmon­ics. There are two types of harmonics, current and voltage. Remedial methods for both will be covered in this article.

Jim McKee (deceased)
Alabama Electric Motor Service 
Sheffield, Alabama 
Technical Education Committee Member 

The slip ring or wound rotor induction motor (WRIM) has been used in a variety of applications. Many of these applications use the WRIM’s high starting torque capabil­ity while limiting current to start and run very high inertia loads such as hammer mills, rolling mills, centri­fuges, and rotary kilns. Other applica­tions utilize the variable speed capability of the WRIM. Probably the most common use of WRIMs for variable speed is in crane and hoist service. Other variable speed uses for the WRIM include wiredraw ma­chines, fans, blowers, pumps and refrigeration compressors. 

Variety of solutions, options 
Many of these applications, if designed today, would utilize a standard induction motor and variable frequency drive (VFD), particularly those where speed control is the desired end result. When older WRIMs or their controllers fail, the best solution often is to replace both motor and control. There are situations, however, where the best solution may be to replace the old controller with a VFD and continue to use the WRIM.