This is accomplished by a motor control, and the most common is a variable frequency drive vfd. Topics motor basics motor construction application of variable speed motors. In order to change the speed of an ac motor, the frequency must be changed. Basics of ac, dc, and ec electric motors part 2 ec and stepper says. The synchronous speed of an ac motor is the speed of the rotating magnetic field set up by the stator winding. To understand how an alternating current ac induction motor works, it helps to look into the basics of magnetism and electromagnetic induction and how they impact the functions of ac induction motors. Explain the concepts of force, inertia, speed, and torque explain the difference.
Basics of motors and motor control welcome to module 16, which is about the basics of motors and motor control. Ac drive installation is as simple as connecting the power supply to the ac drive. Find out here with this article on induction motors. Magnetism and induction a motor converts electrical energy into. Ac drives with afe technology can meet even the most stringent harmonic standards and reduce backup generator sizing. Basics of dc motors for electrical engineers beginners on photo. Electric motors are estimated to now consume over 25% u. Magnetism refers to the force that attracts or repels two objects from each other. The basics of dc and ac motors dc motors rely on carbon brushes and a commutation ring to switch the direction of the current and magnetic field polarity in a rotating armature. As load torque is required from the motor, rotor speed will decrease relative to the rotating field.
Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. Upon completion of basics of ac drives you should be able to. Small dc motors are used in cordless tools, small toys and disk computer drives, however, bigger dc motors are still used in some industrial applications. Direct current will therefore be produced at the output of the. Synchronous speed rpm 120 x frequency divided by the number of poles. This module will discuss both types of motors, and how to control them.
The theory used in the work was collected by studying literature on how electrical motors work, and by simplifying the. Other motors that are included are 1phase induction motors. If a commutator such as that shown in figure 21 is used. The field windings of a series motors are connected in series with the armature windings. The positive end of the battery is always positive relative to the negative end, and the negative end of the battery is. Alternating current ac induction motors are divided into two electrical categories based on their power source single phase and polyphase. Like most motors, an ac induction motor has a fixed outer portion, called the stator and a rotor that. 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. An understanding of many of the concepts covered in basics of electricity is required for basic of ac motors. This is part 1 in a 4 part series of webseminars related to controlling a brushed dc motor using a microcontroller. Differentiate between the various types of generating electric power stations. Singlephase twophase threephase the presentation will describe the basics of the threephase brushless motor because it is the most common version. If motor is used is dc powered then it is called dc servo motor, and if it is ac. The unit as described above, however, would thrive on dc but not operate efficiently on ac.
Sep 27, 2012 learning 101 basics of motors and motor controls. Motor basics magnetism and induction motor speed relationship motor performance motor nameplate information motor construction. Whats the difference between ac, dc, and ec motors. Ac alternating current reverses poles of electromagnetic coil 120 times per sec 60hz coils wound into the stator of the motor create rotating magnetic field magnetic field passing through the conductors of the rotor induces current to flow induced current produces magnetic field around rotor conductors which creates magnet. The rst ac motors synchronous and then induction were invented by tesla in the 1880s. This webseminar will focus on the basics of brushed dc motor construction and some common characteristics. Knowledge of the basics together with powerful new test equipment vastly simplifies the job. Alternating current motors or ac motors are built on the principle that nikola tesla discovered in the late 19th century. Plant engineering understanding ac induction motor basics. Depending on the certifying organization, these courses may be. Basics of ac, dc, and ec electric motors, part 1 ac and dc. The principle of an ac motor is that electric current is applied to electromagnets, creating a rotating magnetic field to convert electrical energy to rotation mechanical energy. An887, ac induction motor fundamentals microchip technology.
A servo motor is an electrical device which can push or rotate an object with great precision. Unit 2 dc motors and generators discussion of fundamentals. Other motors that are included are 1phase induction motors, permanent synchronous motors and synchronous reluctance motors. Dec 05, 2017 basics of ac, dc, and ec electric motors part 2 ec and stepper says. Universal motors are theoretically able to operate on ac or dc. Ac motors are used worldwide in many applications to transform electrical energy into mechanical energy. Ac motors are mainly used for industrial applications such as centrifugal pumps, fans, compressors etc. It is therefore used in starter motors of cars and elevator motors p. If you continue browsing the site, you agree to the use of cookies on this website. The schematics shows the resultant current i in phase with the voltage v. This course covers basics of ac motors and related products. Sep 03, 20 ac motors require slip to induce current in the rotor, and the amount of slip changes as the load on the motor changes.
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. A wall adapter transforms ac into dc, the wall adapter in our lab kit transforms 120 vac into 912vdc. It is just made up of simple motor which run through servo mechanism. The ac induction motor is the most used electrical motor in industrial applications worldwide. From ac motor basics like speed control to the basics of ac motor controller. Early designers of ac motors encountered problems traced to losses unique to alternating current magnetics. Ac drives have the lowest starting current of any starter type. Basics of ac drives ebook pdf download siemens step course. This course is intended to prepare the target persons with the ability to understand and recognize different types, components, theory of operation and applications of all electrical motors.
An outside stationary stator having coils supplied with ac current to produce a rotating magnetic field, and an inside rotor. Basics of ac motors ebook pdf download siemens step course. The stator is a permanent magnet, so the motor is smaller in size. Basics of ac, dc, and ec electric motors part 2 ec and stepper december, 2017 by bill schweber leave a comment part 1 looked at basic ac and dc motors which do not require electronics to operate although the variablefrequency ac motor is an important exception. Upon completion of basics of ac motors you should be able to. An introduction to electrical motors basics course description. This elearning module provides a basic understanding of three phase induction motors. Ac induction motors are one of the most common types of motors used in a variety of applications due to the fact that they run off of ac voltage which is readily available at every outlet. Schematic representation of a sinusoidal voltage of magnitude e applied on a circuit with a resistive load r. Powering industry since replacing the steam engine 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. Motor protection fundamentals ali kazemi, pe regional technical manager. Ac motors are primarily used as a source of constantspeed mechanical. If a commutator such as that shown in figure 21 is used, it will act as a rectifier and convert the induced ac voltage into a dc voltage with ripple, as shown in figure 26. Thus, the voltage provided by a flashlight battery remains steady at about 1.
Seen here are outtakes from free online ac motor drive basics course referenced at. Basics of ac, dc, and ec electric motors part 2 ec and. Its operation is based on the principle that when a current carrying conductor is placed in a. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. List and describe the more commonly used equipment in an electric substation. Dec, 2017 basics of ac, dc, and ec electric motors part 2 ec and stepper december, 2017 by bill schweber leave a comment part 1 looked at basic ac and dc motors which do not require electronics to operate although the variablefrequency ac motor is an important exception. 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 electrons in a wire carrying direct current move slowly, but eventually they travel from one end of the wire to the other because they keep plodding along in the same direction. It also shows the phasor representation of the voltage and current. An electric current that flows continuously in a single direction is called a direct current, or dc. A universal motor is a singlephase series motor, which is able to run on either alternating current ac or direct current dc and the characteristics are similar for both ac and dc. How does a threephase alternating current induction motor work. Introduction to ac motors ac motors electronics textbook. Basics of dc motors for electrical engineers beginners.
Basics of ac motors ebook pdf download siemens step course good one. This conversion is usually obtained through the generation of a. In addition to providing basic information about ac motors in general, this course also includes an overview of siemens simotics nema ac motors. These problems were encountered when adapting dc motors to ac operation. The basic idea of an electric motor is to generate two magnetic fields. The first device used to stop and start electric motors was a simple knife blade. An introduction to electric motors stmicroelectronics. This application note discusses the basics of an ac induction motor.
So when a motor fails to operate it may not be obvious what the problem is. Electric motors have had a reputation for being a mix of science and magic. Aug 31, 2016 from ac motor basics like speed control to the basics of ac motor controller. Basics of an ac drive with motor basics slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. A compensating winding is added, and the pole pieces are laminated to prevent wasteful circulating current and attendant heat rise.
Whatever the application, the function of the contactor is always the same. This course covers basics of ac drives and related products. An electric motor is a machine that converts electrical energy to mechanical energy. All ac motors have the same basic components, a stator and rotor. The stator is the stationary coils in the motor where the current is produced to create the.
Or, as defined by nema, to repeatedly establish and interrupt an electrical power circuit. Scroll to the bottom to watch the youtube tutorial on this article the induction motor is the most common type of electrical motor used in industry, and its used in pretty much everything, from elevators. If you want to rotate and object at some specific angles or distance, then you use servo motor. Ac induction motors how ac motors work explain that stuff. To run well off ac mains, the motor needs modifications. Explain the concept of force, inertia, speed, and torque explain the. Directindustry 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. In most cases, the considerations can be extended to the other types. Mostafa elshahed objectives learn a brief history of the electrical power systems construction. The theory of operation of induction motors is based on a rotating magnetic field.
316 334 180 1112 1227 310 1157 1512 1258 165 965 191 1324 683 149 868 185 1266 729 380 883 240 586 1456 256 439 1238 74 182 896 1410 1008 271 300 715 1056 296 726 1119 1155 776 268 888 1353 703 1199 1071 254 1486