Magnetism and induction a motor converts electrical energy into mechanical energy ac alternating current reverses poles of electromagnetic coil 120 times per sec 60hz coils wound into the stator of the motor create. An introduction to stepper motors university of arizona. This is accomplished by a motor control, and the most common is a variable frequency drive vfd. Introduction to truly understand the operating principles of an electronic drive, it is first necessary to understand basic direct current dc and alternating current ac motor theory. In this example an unloaded motor connected to a dc drive is being operated at 100% speed. This chapter deals with the basic mechanisms of motor operation, so readers who are. The dc can be considered a particular case of the general ac, with frequency equal to zero. Ac motors are available in single or threephase configurations, while dc motors are always singlephase.
Dec 05, 2017 basics of ac, dc, and ec electric motors part 2 ec and stepper says. Spur, helical or worm gears may be used in single or. Dc motor online training courses training from dupont. As of now we only discuss about dc circuit and its theory. The stator magnetic field is generated by a permanent magnet. Alternating current ac induction motors are divided into two electrical categories based on their power source single phase and polyphase.
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. Basic construction and operating principle like most motors, an ac induction motor has a fixed outer portion, called the stator and a rotor that spins. Thus, the voltage provided by a flashlight battery remains steady at about 1. Synchronous servomotor o permanentfield ac synchronous motor. A motor needs three basic thingsa magnetic field, a current carrying conductor, harnessing the created force on current carrying conductor due to magnetic field. Types of dc motors dc motor are of 3 types they are 1. The dc motor is the simplest of the motors discussed here.
Learners study the interaction between the conductors of the stator and the armature inside a dc motor, which causes the shaft to rotate. Sep 22, ac commutator motors, like comparable dc motors, have higher starting torque and higher speed than ac induction motors. Ac motors are mainly used for industrial applications such as centrifugal pumps, fans, compressors etc. The basic construction difference between ac and dc motor is that dc motor has direct conduction current supply to rotor and ac motor has inductive supply to rotor no direct conduct.
That means, the full rotation of the rotor is divided into equal number of steps, and rotor rotates through one step for each current pulse. 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. 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. Objective identify the components of an ac motor and explain their function. Ac induction motor is the most widely used type of electric motor in the. Ac motors consist of several parts, including a stator and rotor. Singlephase twophase threephase the presentation will describe the basics of the threephase brushless motor because it is the most common version. The series is designed to familiarize students with motor basics, parts of a dc motor, how dc motors operate, and different types of dc motors. Dc motors principle of operation resources for engineers. A dc motor is comprised of a wound armature, commutator, brushes and magnetsall within a totallyenclosed housing. Dec 07, 2014 dc motor introduction, principle and working introduction. Ac series motor principle, types, characteristics and. The reference of dc or ac refers to how the electrical current is transferred through and from the motor.
It is necessary to vary to dc voltage in order to control the speed of a dc motor. The motor draws current from this power source in proportion to the torque load applied to the motor shaft. Whats the difference between ac, dc, and ec motors. A stepper motor is an electric motor that rotates in discrete step increments. An introduction to stepper motors xinda hu university of arizona college of optical sciences introduction. Dc motors are rarely utilized in normal applications as a result of all electrical supply firms furnish electrical energy but, for special applications like in steel mills, mines and electric traction, its advantageous to convert ac into dc so as to use dc motors. The basic principle of a dc motor is the creation of a rotating magnet inside the. 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. In most cases, the considerations can be extended to the other types.
The electronic commutation switches the current back and forth to mimic ac current and keep the motor turning. Handson practice handson practice is a necessary part of learning and this course offers handson opportunities to perform fundamental motor and drive tasks. Stepper motor also called as step motor is basically a brushless dc motor, whose rotor rotates through a fixed angular step in response to input current pulse. Also ac series motor is a modified dc series motor what does this mean. If you continue browsing the site, you agree to the use of cookies on this website. Ac motors are used worldwide in many applications to transform electrical energy into mechanical energy. 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. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. Motor basics magnetism and induction motor speed relationship motor performance motor nameplate information motor construction. Basics of ac, dc, and ec electric motors part 2 ec and stepper says.
Basics of dc motors for electrical engineers beginners on photo. 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. The handbook includes information on alternating current ac and direct current dc theory, circuits, motors, and generators. Basics of ac, dc, and ec electric motors part 2 ec and. Basics of dc motors for electrical engineers beginners. Oct 03, 2012 basics of ac drives why would you want them. 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. Dc motors are the most common type of motor for low voltage andor high starting torque applications, most often seen in the automotive and agricultural industries. A circuit that deals with ac is referred to as ac circuit and a circuit with dc source is termed as dc circuit. Introduction to dc circuits electric voltage and current. Subhajit bose03 shuvankar das02 binoy mourya09 sushobhan sarkar06 prosenjit debnath35 3. Brushless motors overview there are different types of brushless motors. The positive end of the battery is always positive relative to the negative end, and the negative end of the battery is. An introduction to electrical motors basics course description.
It is therefore used in starter motors of cars and elevator motors p. We know that the electricity is of two types, alternating current ac and direct current dc. Stepper motors operate differently from other dc motors, which simply spin when voltage is applied. A dc drive supplies voltage to the motor to operate at a desired speed. Learn about controlling motor speeds and energy savings, as well control strategies. This reading is a very brief introduction to four most basic types of electric motors. A dc motor is an electric motor that runs on direct current power. The permanentfield ac synchronous servomotors and the ac asynchronous servomotors will be looked at in more detail below. Difference between ac and dc motors instrumentation and.
Sep 19, 2012 basics of an ac drive with motor basics slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. 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. Its operation is based on the principle that when a current carrying conductor is placed in a. Ac and dc drive print set, which contains schematics of selected allenbradley drives. There are direct current or dc and alternating current or ac motors. Terms and definitions the motors are designated as follows in this publication. In an electric motor, the operation is dependent upon simple electromagnetism. Difference between ac and dc motors somewhat lies in the name as their name reflect their working style. In order to change the speed of an ac motor, the frequency must be changed. In addition to providing basic information about ac motors in general, this course also includes an overview of siemens simotics nema ac motors.
Ac motors require slip to induce current in the rotor, and the amount of slip changes as the load on the motor changes. The positive end of the battery is always positive relative. The frequency of an alternated circuit is measured by the number of times the. 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. Introduction to simple dc circuit and its parameters. The voltage in a directcurrent circuit must be constant, or at least relatively constant, to keep the current flowing in a single direction. Dc motor introduction, principle and working my tech info. The movement of each step is precise and repeatable. A gearmotor is made up of an electric motor, either dc or ac, combined with a geared speed reducer. Apr 23, 2018 dc motors are the most common type of motor for low voltage andor high starting torque applications, most often seen in the automotive and agricultural industries.
Learners study the interaction between the conductors of the stator and the armature inside a dc motor, which causes the shaft to. Brushless dc motors before the age of electronics, all dc motors had to have brushes or some other type of mechanical commutator. In addition, the field construction of the dc motor and the various elements of the commutator are detailed, as well as interpreting the wiring diagrams and troubleshooting dc motor problems. Principles and working of dc and ac machines bits pilani.
Overview the acdc motor theory course was specifically developed for electricians and electronic technicians as well as for the multicraft training needs of process and manufacturing facilities. Basics of an ac drive with motor basics slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. A thyristor is one type of device commonly used to convert ac to dc. Dc motors are therefore useful at low rotation speeds and versatile when confronted by varying loads.
There are two terminals, and when you apply direct current to one terminal and ground the other, the motor spins in one direction. Basics of ac, dc, and ec electric motors, part 1 ac and dc. This conversion is usually obtained through the generation of a. Dc motor introduction, principle and working introduction. What is common to all the members of this family is that the basic physical process involved in their operation is the conversion of electromagnetic energy to mechanical energy, and vice versa. Mechanical energy what is an electric motor an electric motor is a device converting electrical energy into mechanical energy usually a torque. 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. Converting ac to dc thyristor a primary function of a dc drive, such as the simoreg 6ra70 dc master, is to convert ac voltage into a variable dc voltage. This application note discusses the basics of an ac induction motor. Module 6 dc motors this module describes the types of dc motors and includes discussions of speed control, applications, and load characteristics. 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. The stator is a permanent magnet, so the motor is smaller in size. In an ac motor, energy comes from magnetic fields generated through coils wrapped around the output shaft. This video is integrated as part of our generators page.
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. Operating principle of dc motors as stated in unit 1, motors turn because of the interaction between two magnetic fields. This unit will discuss how these magnetic fields are produced in dc motors, and how magnetic fields induce voltage in dc generators. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. Electric dc motors direct current motor basics,types and. This course consists of 11 interactive, online lessons that address ac and dc motor theory.
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