The machines and equipment used in mining must provide reliable, safe and efficient operation in challenging and hostile environments. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. A 5 kvdc insulation resistance test is no substitute for a proper ac overvoltage withstand test. Multiple choice questions with answers on refrigeration and airconditioning set 07 practice test. Its operation is based on the principle that when a current carrying conductor is placed in a. Unit 2 dc motors and generators 67 the operating principles of direct current dc motors and generators. Describe the principle of magnetic induction as it applies to ac generators. This version of the easa motor rewind database software takes a large. Introduction to generators and motors, is an introduction to generators and motors, and covers the uses of ac and dc generators and motors in the conversion of electrical and mechanical energies. Multiple choice questions with answers on dc generators set. Multiple choice questions with answers on refrigeration and airconditioning set 07. So we know that ac generators and ac motors tend to be simpler than dc generators and dc motors.
Some motors, such as a grinder, have a shaft extending from both. The dc generators could be controlled back to an unmoving speed as batteries tend to be stimulating to recover considerably more fuel. An ac motor is an electric motor driven by an alternating current ac. Using quality materials and thorough testing procedures, our experienced electric motor repair professionals can provide 247 service and support. Electric motors, generators, alternators and loudspeakers are explained using animations and schematics. The wind blows constantly between the desert and mountains of california. 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. Inspection and test procedures of rotating machinery, synchronous motors and generators on photo. Basic generating principles are most easily explained through the use of the elementary ac generator.
Ac is used to deliver power to houses, office buildings, etc. The ac motor is depends on the reversing magnetic field produced by alternating current through its stationary coils of wire to make the magnet rotate. Abb motors and generators is a leading company in technology that offers many motor and generator solutions. 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. This is a resource page from physclips, a multilevel multimedia introduction to physics download the animations on this page. Principles and working of dc and ac machines bits pilani. Ac testing should be performed, not dc, or worse, no hv testing at all. The rotatingarmature alternator is similar in construction to the dc generator in that the armature rotates in a stationary magnetic field as shown in figure 31, view. The first copy of this software is free to active and allied members. The fourth connection, separatelyexcited, can be made to. The conductor coil and its core are called the armature, connecting the armature to the shaft of a mechanical power source, for example an motor, the copper. This valuable resource is available only to easa members.
Synchronous and asynchronous electricmotors the electric motor is an electromechanical continuous energy conversion equipment that converts electrical energy into electrical energy mechanical energy. Other members of the family are the direct current dc motor or generator, the induction motor or generator, and a number. Surely there must be more to it than design details of generators and motors. Multiple choice questions with answers on dc generators.
The frequency of an alternated circuit is measured by the number of times the. Ac alternators and motors a pdh online course for engineers. The stator is a permanent magnet, so the motor is smaller in size. Variable speed drives vsds, motors, gearing and bearings are indispensible for key processes such as cane milling, or beet slicing, extraction and crystallization, and play a critical role in generating energy. Alternating current ac alternating current describes the flow of charge that changes direction periodically. 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.
Electrical machines generators and motors electrodynamics. Dc motor principle a machine that converts dc power into. Important questions and answers on electric motor with pdf to. Unit 16 electric motors washington state university. It is therefore used in starter motors of cars and elevator motors p. Updated to the 2011 national electrical code, electricity 4. Kuphaldt this book is published under the terms and conditions of the design science license. Generating ac ac can be produced using a device called an alternator. Motors and generators are the exact same device, but motors convert electrical energy into mechanical energy if the shaft on a motor is spun, a voltage is. Home download center electrical engineering books and technical guides electrical engineering guides introduction to motor and generator. The dc can be considered a particular case of the general ac, with frequency equal to zero. Some motors, such as a grinder, have a shaft extending from both ends. Alternating current generators learning objectives upon completion of this chapter, you will be able to. This portable document format \ pdf \ file contains bookmarks, thumbnails, and hyperlinks to help you navigate through the document.
Pdf utilization of dc motorac generator system to convert the. Freon group of refrigerants are a inflammable b toxic c noninflammable and toxic. They rotate because some mechanism reverses the current at. Therefore the operation of the dc motor and ac generator was studied theoretically and practically by construct a 5. It commonly consists of two basic parts, an outside stationary stator having coils supplied with alternating current to produce a rotating. An ac motor of this type may be part of a pump or fan or. There are many types of ac motors, but this course focuses on threephase ac. Important questions and answers on electric motor with pdf. The 18 exercises in this manual, acdc motors and generators, provide a foundation for further study of rotating machines. Electric motors and generators introduction a simple ac generator a simple dc generator dc generators or dynamos ac generators or alternators dc motors ac motors universal motors electrical machines a summary chapter 23. A generator consists of a stationary portion called the. Synchronous and asynchronous electromechanicalsystems dr.
Generators, motors, transformers, and solenoids each use the principle of electromagnetism. Generators, dc motors, ac theory, ac power, ac generators, voltage. Pdf design and implementation of an ac power generator using. Electric motors and generators physics animations and. Introduction to ac motors ac motors electronics textbook. This relative simplicity translates into greater reliability and lower cost of manufacture. Together with extensive mining experience and a wide portfolio. The dc motor rotates the armature of the alternator in the field coil at high speed when powered. Generators, dc motors, ac theory, ac power, ac generators, voltage regulators, ac motors, transformers, test instruments, electrical distribution. Generator working principle and explain about ac and dc.
Basic ac electrical generators 1 introduction faradays law. As a result, the voltage level also reverses along with the current. The rotor shaft extends from one end of the motor for connection to the driven device or machine. This version of the easa motor rewind database software takes a large leap forward with the data that it provides members. This portable document format \ pdf \ file contains bookmarks, thumbnails, and hyperlinks to help you navigate through. A generator is the opposite of a motor it transforms mechanical energy into electrical energy.
Electric motors usually consist of a coil rotating inside the magnetic field of either a. Together with extensive mining experience and a wide portfolio of life cycle services, abb is well positioned to tackle the industrys most demanding situations. Transients in rl, rc and rlc circuits with dc excitation. Ac motors ac motors are used worldwide in many applications to transform electrical energy into mechanical energy. Introduction most of the electrical power used aboard navy ships and aircraft as well as in civilian applications is. While dc motors need brushes to make electrical contact with moving coils of wire, ac motors do not. Vlf technology can be used for ac withstand and ac diagnostic testing. Vlf use for motors and generators was first defined by the ieee standard 4331974, upgraded in 2009. These problems were encountered when adapting dc motors to ac operation. The arrangement is so simple that it can be remotely operated.
Ac generators advantages the slip rings of an ac generator have a continuous surface that allows the brushes to remain in contact with the rings surface. A 220 volt dc shunt motor has a speed of 1200 rpm and an armature current. Electric motors usually consist of a coil rotating inside the magnetic field of either a permanent magnet or an electromagnet. The course then moves from a basic ac alternator to several types of practical ac alternators. Describe the differences between the two basic types of ac generators. The elementary generator the simplest elementary generator that can be built is an ac generator. State what component causes a generator to produce direct current rather than alternating current. Electric motors and generators university of new south wales.
The stored power is carries to loads through dcac converters. Variable speed drives vsds, motors, gearing and bearings are indispensible for key processes such as cane milling, or beet slicing, extraction and crystallization, and play a critical role in generating energy savings, improving productivity, and reducing costs. This is a resource page from physclips, a multilevel multimedia introduction to physics. Inspection and test procedures for rotating machinery.
Ac motors are used worldwide in many applications to transform electrical energy into mechanical energy. Pdf reliable and efficient supply of electricity is an unavoidable prerequisite to development of any. Basic generating principles are most easily explained. Synchronous and asynchronous electricmotors the electric motor is an electromechanical. Chapter one covers ac alternators and begins with an overview of a basic ac alternator. Ac as it will be shown later, alternators operate with both alternating ac and directcurrent dc electric power. Single phase emf generation, average and effective values of sinusoids, j operations, complex representation of impedances, phasor diagrams, power factor, power in complex notation, solution of series and parallel circuits. For this reason, the ac generator will be discussed first. The polepole ac voltage drop shall not exceed 10 percent variance.
Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. In fact, ac and dc motor designs are very similar to their generator counterparts. Horner industrial group services and maintains a wide range of electric motors. The different types of dc motors and generators and their particularities. List the advantages and disadvantages of the two types of ac generators. Abb library is a web tool for searching for documents related to abb products and services. An introduction to electric motors home stmicroelectronics. Though few ac motors today bear any resemblance to dc motors, these problems had to be solved before ac motors of any. C generators are classified according to the way their magnetic field is developed in the stator of the machine.
It commonly consists of two basic parts, an outside stationary stator having coils supplied with alternating current to produce a rotating magnetic field, and an inside rotor attached to the output shaft that is given a torque by the rotating field. The modules listed in the overview are linked to the corresponding. With this document abb takes the commitment and responsibility that the products respect the atex directive. The stored power is carries to loads through dc ac converters. A threephase ac generator is designed to produce threephase ac power by building.
Accurate analysis of the stator winding insulation. Ec declaration of conformity for low voltage motors for explosive atmospheres, product types m3jp, m3kp, m3jm, m3hp, m3gp, m3aa, english. An enterprising individual set up some towers with windmills driving induction generators through gearboxes. Using quality materials and thorough testing procedures, our experienced electric motor repair professionals can provide 247. Electric motors and generators introduction a simple ac generator a simple dc generator dc generators or dynamos ac generators or alternators dc motors ac motors.
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