Though few ac motors today bear any resemblance to dc motors, these problems had to be solved before ac motors of any type could be properly designed. The types discussed in the following paragraphs are typical of the more predominant ones in use. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. Volume 3 of 4 module 7 basic ac theory this module describes the basic concepts of alternating current ac electrical circuits and discusses the associated terminology. Electric motors and drives fundamentals, types and applications third edition austin hughes senior fellow, school of electronic and electrical engineering, university of leeds amsterdam boston heidelberg london new york oxford paris san diego san francisco singapore sydney tokyo newnes is an imprint of. Module 6 dc motors this module describes the types of dc motors and includes discussions of speed control, applications, and load characteristics. Have you ever noticed what kind of motor drives the ceiling fan. Various types of ac induction motors are available in the market. Generating ac ac can be produced using a device called an alternator. An introduction to electric motors stmicroelectronics. For motors used in gas and oil terminals, the casing must be of intrinsically safe, thus it may either have a enclosed casing or a pipe ventilated arrangement such that the sparks produced inside. The induction motor is that the rotor of the synchronous moto. Brushless motors overview there are different types of brushless motors.
An electric motor is an electromechanical device that converts electrical energy into mechanical energy. For small power conversion, the single phase ac motors are mostly used. They operate such devices as starters, flaps, landing gears, and hydraulic pumps. Synchronous motors are constructed of a stator, rotor and synchronous motors are used in a wide range of applications. Rather than motor design, their chief concerns lie with the selection, system installation, operation and performance evaluation of. On the basis of type of current i single phase motors ii three phase motors as regards their speed i constant speed motors.
Types of electric motors electric motors dc motors other motors h ac motors s unt motor separately excited induction motor stepper motor motor brushlessdc motor series motor hysteresis motor permanent magnet dc pmdc synchronous motor reluctance motor compounded motor universal motor. Induction motor, synchronous motor and ac commutator motor. The types of ac motors mainly include synchronous, asynchronous, induction motor. They are ac type, dc type, brushless, brushed, phase type like single phase, two or three phases, etc. Unit 16 electric motors objectives after studying this unit, the student will be able to state the purpose of an electric motor. Ac motors ac motors are used worldwide in many applications to transform electrical energy into mechanical energy. Easily operate ac motors by connecting the motor to an ac power supply. Early designers of ac motors encountered problems traced to losses unique to alternating current magnetics. Ac motors are mainly used for industrial applications such as centrifugal pumps, fans, compressors etc. Ac induction motors have some disadvantages as well. Its operation is based on the principle that when a current carrying conductor is placed in a. The synchronous speed of an ac motor is the speed of the rotating magnetic field set up by the stator winding synchronous speed rpm 120 x frequency divided by the number of poles. Therefore, ac commutator motors are used for wide rage speed control at around unity power factor. Types of ac motors there are two distinct types of ac motors, synchronous and induction.
The three phase induction motors are simple in construction, rugged, low cost. Singlephase induction motors i splitphase type ii capacitor start type iii capacitor start capacitor run type v shadedpole type 2. The induction motor or asynchronous motor always relies on a small difference in speed between the stator rotating magnetic field and the rotor shaft speed called slip to induce rotor current in the rotor ac winding. Covers the main types of ac motors including triphase, multiphase, and doubly fed induction motors, wound rotor, permanent magnet, and interior pm synchronous motors illustrates the usefulness of the advanced control methods via industrial applications including electric vehicles, high speed trains, steel mills, and more. The classification of electric motors can be done based on considerations like the type of power source, construction, motion output type, and application. Ac series motor or the universal motor is an electric motor which operates in either ac or dc power at the same speed and output. Below is the respective difference of synchronous motor and induction motor. Ac motors are used worldwide in many applications to transform electrical energy into mechanical energy. These types of motors have different outer cage arrangements, depending upon the usage or any special industrial requirement.
They are easy to handle and have features that can be con. Single phase induction motor and three phase induction motor. There are two types of induction motors, one with wound type rotor, also called slipring motor. Also ac series motor is a modified dc series motor what does this mean. A springloaded auxiliary manual starting switch connected power to this second motor for a few. Classification of electric motors part two electrical. For induction motors, there is no externallyapplied rotor excitation, and current is instead induced into the rotor windings due to the. The single phase ac motor is nearly small in size, and it provides a variety of services in the home, office, business concerns, factories, etc. It has the following main advantages and also some disadvantages. From tiny hysteresis motors that drive electric clocks to huge synchronous motors that develop more than 50,000 hp, the alternating current ac motor has become an indispensable part of everyday life. Different types of electric motors and their applications. Yet small brushed ac motors, similar to the dc variety, persist in small appliances along with small tesla induction motors. Introduction to ac motors ac motors electronics textbook. There are many types of ac motors, but this course focuses on threephase ac induction motors, the most common type of motor used in industrial applications.
An ac motor of this type may be part of a pump or fan or connected to some other form of mechanical equipment such as a winder, conveyor, or mixer. The synchronous motor rotates at the same rate as the frequency of the supply current, a fact that gives the motor its name. Singlephase twophase threephase the presentation will describe the basics of the threephase brushless motor because it is the most common version. The mechanical energy can be used to perform work such as rotating a pump impeller, fan, blower, driving a compressor, lifting materials etc.
An electric motor is an electrical machine that converts electrical energy into mechanical energy. Types of ac motor definition and classification of ac motor. Practical electric motor handbook pdf by irving m gottlieb. The main advantage of dc motors over ac motors is that speed is more difficult to control for ac motors. Ac motors are electric motors that rotate by using power from a commercial ac power supply. Beginners electrical design course is an introduction only for beginners to know general basic information about motors and pumps as a type of power loads. Mechanical energy what is an electric motor an electric motor is a device converting electrical energy into mechanical energy usually a torque. List the advantages and disadvantages of the two types of ac generators.
Ac is used to deliver power to houses, office buildings, etc. Ac series motor principle, types, characteristics and. Induction motors use shorted wire loops on a rotating armature and obtain their torque from currents induced in these loops by the changing magnetic field produced in the field coils. There are two types of induction motors, one with wound type rotor, also called slipring motor and another one with squirrelcage rotor. Electric motors defined as electromechanical devices that convert electrical energy to mechanical energy. Classification of electric motors electrical knowhow.
These omnipresent devices come in many varieties, but generally fall into two categories. Three phase induction motors are used where large amounts of power are required. The stator in the electric motor generates the field current which rotates in a stable speed based on the ac frequency. This classification of induction motor is based on the type of power supply required for its. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. The rotor and stator are each connected from a different power supply, this gives another degree of freedom for controlling the motor over the shunt.
Because the rotor is free to turn, it follows the rotating magnetic field in the stator. This book, therefore, targets the large body of workers engineers and students reasonably versed in engineering concepts who feel the need for practical insights relating to electric motors. Singlephase motors are generally built in the fractionalhorsepower range and may be classified into the following four basic types. The two main types of ac motors are induction motors and synchronous motors. An ac motor of this type may be part of a pump or fan or. As it will be shown in later chapters, both types of electrical conduction are found in turbogenerators. Alternating current ac alternating current describes the flow of charge that changes direction periodically. Know about the different categories that these motors can be classified into. Almost all the domestic appliances such as refrigerators, fans. Explain the operation of multiphase ac generators and compare with singlephase. As a result, the induction motor cannot produce torque near synchronous speed. This final thesis will mostly be dedicated to induction motors but also to synchronous permanent magnet and reluctance motors.
Based on the working principle, there are mainly three types of ac motors. Electric motors can be powered by direct current dc sources, such as from batteries, motor vehicles. These two types of motors differ in how the rotor field excitation is supplied. The three phase ac motors are mostly applied in the industry for bulk power conversion from electrical to mechanical. An ac motor is an electric motor driven by an alternating current ac. His new type of motor, the ac induction motor, is the workhorse of the industry to this day. Basically, there are three types of electric motors, ac motors like synchronous and asynchronous motors, dc motors like brushed and brushless and special purpose motors.
Know where these different types of motors are used. Unit 16 electric motors washington state university. Since there is such a wide variety of these motors, it is impossible to describe all of them. By far the most commonly used ac motor is the induction motor. These problems were encountered when adapting dc motors to ac operation. The rotor and stator windings are connected in parallel. Induction motors have constant speed characteristics and low operating power factor. Ultimately, motors are the interface between the electrical and mechanical systems of a facility.
Single phase series motor, repulsion motor and scharge motor are types of ac commutator motor. Compare the types of rotors used in ac generators, and the applications of each type to different prime movers. Describe the placement of stator windings in twophase, ac motors using rotating. A good material for the poles of a pmdc motor should have the apposite of the above. Although ac induction motors are easier to design than dc motors, the speed and the torque control in various types of ac induction motors require a greater understanding of the design and the characteristics of these motors. Either type may be single phase, two phase, or three phase. This conversion is usually obtained through the generation of a.
What is the difference between ac motors and dc motors. Large motors have an output of 3 kw kilowatt or more and are normally three phase machines. Rotating armature generator in the rotating armature ac generator as illust rated in figure 1, the stator provides a. The working of the synchronous motor mainly depends on the 3phase supply.
Read here to know about these electrical motors and their exhaustive classification. To compensate for this, ac motors can be equipped with variable frequency drives but the improved speed control comes together with a reduced power quality. Generator types various types of alternating current generators are utilized today. Singlephase motors introduction singlephase ac motors are the most common motors built. Its ruggedness and simplicity make for long life, high reliability, and low maintenance. Different motors are suitable for different applications. There are many types of ac motors, but this course focuses on threephase induction motors, the most common type of motor used in industrial applications. Ac motors in common use today may be divided into two broad categories. Explain the factors that determine the maximum power output of an ac generator, and the effect of these factors in rating generators.
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