Print this page DC Alternators and Motors
Lee Layton, P.E.
Course Outline
This course is divided into two chapters. Chapter one covers DC generators and includes an overview of a basic DC generator. From the elementary generator, the course discusses the effects of adding coils and poles, the application of compensating windings and interpoles, and armature losses. From this basic understanding, typical real-life DC generators are discussed in detail. Chapter two follows the same format as Chapter one, and expands on the DC generator concept to explain DC motors. Practical DC motors are discussed, includes series-wound and shunt-wound motors.
This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.
Learning Objective
Upon completion of this course, student will be able to:
- Know the principle by which generators convert mechanical energy to electrical energy;
- Know what component causes a generator to produce direct current rather than alternating current;
- Understand how field strength can be varied in a DC generator;
- Know the purpose of interpoles;
- Explain the causes of armature losses;
- List the types of armatures used in DC generators;
- State the term that applies to voltage variation from no-load to full-load conditions and how it is expressed as a percentage;
- State the factors that determine the direction of rotation in a DC motor;
- Describe the main differences and similarities between a DC generator and a DC motor;
- Describe the cause and effect of counter EMF in a DC motor;
- Know the advantages and disadvantages of the different types of DC motors; and
- Discuss the means of controlling the speed and direction of a DC motor.
Intended Audience
This course is intended for electrical engineers and others who want to understand how DC generators and motors operate.
Benefit to Attendees
The generation and consumption of power for useful work is based on converting another fuel source into electricity and then using an electric motor to perform the work. This course explains how both DC generators and motors work along with the advantages and disadvantages of these devices.
Course Introduction
An electric generator is a device that converts mechanical energy into electrical energy. A generator forces electric charge to flow through an external electrical circuit. The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. Many motors can be mechanically driven to generate electricity and frequently make acceptable generators.
The dynamo was the first electrical generator capable of delivering power for industry. The dynamo uses electromagnetic induction to convert mechanical rotation into direct current through the use of a commutator. A dynamo machine consists of a stationary structure, which provides a constant magnetic field, and a set of rotating windings which turn within that field. On small machines the constant magnetic field may be provided by one or more permanent magnets; larger machines have the constant magnetic field provided by one or more electromagnets, which are usually called field coils. Through a series of accidental discoveries, the dynamo became the source of many later inventions, including the DC electric motor, the AC alternator, the AC synchronous motor, and the rotary converter.
Course Content
This course content is in the following PDF document:
Please click on
the above underlined hypertext to view, download or print the document for your
study. Because of the large file size, we recommend that you first save the
file to your computer by right clicking the mouse and choosing "Save Target
As ...", and then open the file in Adobe Acrobat Reader. If you still experience
any difficulty in downloading or opening this file, you may need to close some
applications or reboot your computer to free up some memory.
You may need to download Acrobat Reader to view and print the document.
Course Summary
This course has been a review of the DC generator and DC motor. The DC generator is the basic device to convert mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. Many motors can be mechanically driven to generate electricity and frequently make acceptable generators.
From the basic DC generator came the discovery of a DC electric motor, the AC alternator, the AC synchronous motor, and the rotary converter.
Quiz
Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.
DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.
