It works on the principle of electromagnetic induction i. An alternating current generator, or ac generator, produces an alternating current, which means the voltage produced alternately reverses from positive to negative polarity, producing a corresponding change in the direction of current flow. The wire will be pushed up in this motor example notes. Introduction to alternating current and transformers, is an introduction to alternating current ac and transformers, including basic ac theory and fundamentals of electromagnetism, inductance, capacitance, impedance, and transformers. Explain the operation of multiphase ac generators and compare with singlephase. Therefore any discussion in this book about the power. The faradays law states that whenever a conductor is placed in a varying magnetic field, emf is induced and this induced emf is equal to the rate of change of flux linkages. A governor connected to the prime mover regulates its speed and controls the amount of mechanical power transmitted to the generator. An ac generator, or alternator, is used to produce ac voltages for transmission via the grid system or, locally, as portable generators. View answer ncert question 16 the essential difference between an ac generator and a dc generator is that. It consists of a rectangular coil of wire which can be rotated about an axis.
Some materials called conductors have loosely held electrons that can flow. Alternating current generators, typically referred to as ac generators, generally work on the same principle as direct current generators. Basic ac theory ac generation ac generation an understanding of how an ac generator develops an ac output will help the student analyze the ac power generation process. Without any of these parts, electricity cant be produced. Much like a dc generator, an ac generator requires a coil to cut across the force lines of a magnetic field. Cbse ncert notes class 12 physics electromagnetic induction. Ac generator has slip rings while the dc generator has a commutator. Electric generator class 10 working, principle, diagram. An electrical generator is a device that converts mechanical energy to electrical energy. View answer ncert question 6 b state whether the following statements are true or false. Ac motors are widely used to drive machinery for a wide variety of applications. Other members of the family are the directcurrent dc motor or generator, the induction motor or generator, and a number of derivatives of all these three. The direction of the lines of force is given by the law of the screwdriver.
The basic principle of an ac generator is shown in figure 1. The main advantage of ac is ease of power distribution. Kingsley, electric machinery, mcgrawhill book company, inc. Industrial solar pv facilities use dc ac converters, again not perfectly e cient, to make their power saleable. Figure shows the plots of the current and voltage as a function of time for the inductor. Learn the essentials of electrical grounding and bonding.
These generators are generally maintenance free, because of absence of brushes. The generators ac output voltage can be transferred from the slip rings through the brushes to an external circuit. His father, milutin tesla 18191879, was an eastern orthodox priest. It works based on principle of faraday law of electromagnetic induction. Whenever the magnetic flux changes an emf will be induced in the coil. The generation of alternating currents ac is based on the phenomenon of electromagnetic induction. Generator working principle and explain about ac and dc. Alternating current ac is an electric current which periodically reverses direction, in contrast to direct current dc which flows only in one direction.
Designed to provide readers with a thorough introduction to alternating current electrical characteristics and circuit construction, ac theory, 3rd edition explores the complexities of this more advanced circuit theory by building on the basics established in direct current theory. We know that in order to induce a sinusoidal voltage in a wire coil, the magnetic flux linking the turns of wire in the coil must follow a sinusoidal path over time, phaseshifted 90 o from the voltage waveform. Now consider an ac circuit consisting only of a capacitor and an ac generator. Ac generator theory ac electric circuits pdf version. These generators are packaged with an engine or turbine to be used as a motor generator set and used in applications like naval, oil and gas extraction, mining machinery, wind power plants etc. Generators, dc motors, ac theory, ac power, ac generators, voltage. 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. Therefore, when running as a generator, the machine takes reactive power from the ac power line and supplies active power back into the line. Fundamentals of ac generators 6241 cummins training.
Refrigerator, washing machines, oven, lights, fan etc. It is a device which converts mechanical energy into alternating form of electrical energy. The basic parts of an ac generator are the mechanical power, the magnets and one or more rotors. There are two types of generators dc generators and ac generators. Nikola tesla was born an ethnic serb in the village smiljan, lika county, in the austrian empire present day croatia, on 10 july o. Ac generator principle of working, parts and schematic diagram.
Ac generators, also known as alternators, is a machine that converts mechanical energy into alternating electrical energy. Introduction there are two types of generators, one is ac generator and other is dc generator. The synchronous generator connection with wind turbine is shown in fig. Each atom consists of an equal number of protons positive and electrons negative.
The gas turbine converts the f76 fuel into mechanical power. These different behaviors, described below, lead to different responses in ac circuits. An electrical machine used to convert mechanical energy into electrical energy is called a. Its possible to generate direct current from rotating magnetic fields. On the other hand, a dc voltage source or an acdc converter is required for synchronous generators in wind applications in order to produce the required excitation voltage for the field windings. Take the ac generator theory ac electric circuits worksheet. The synchronous electrical generator also called alternator belongs to the family of electric rotating machines. Before we can explain the working principle of a dc generator, we need to cover the basics of generators there are two types of generators dc generators and ac generators. However, all electric power systems to which industrial generators are connected are threephase systems.
An electric generator works on the principle of electromagnetic induction. Synchronous generator an overview sciencedirect topics. Ac power, what would a magnetic compass do that was placed in the center. The elementary generator the simplest elementary generator that can be built is an ac generator. Introduction to basic notions on electric power 5 electric current conductor lines of force fig. For this reason, the ac generator will be discussed first. The basic function of a generator is to convert motion into electricity.
Instead of multiple sets of windings, it only has one set of windings. Power factor is a dynamic value between 0 and 1 which depends on the operating conditions of the ac circuit. Compare the types of rotors used in ac generators, and the applications of each type to different prime movers. A dc generator produces direct power, while an ac generator produces alternating power. Mileaf, harry, electricity one seven, revised 2nd edition, hayden book company.
All of our household appliances runs on ac current. Explain the underlying principle and working of an electric. The active power supplied back in the line is proportional to slip above the synchronous. Ac power alternating current generation explained duration.
Note again that the voltage and current are not in phase. The generator in turn converts the mechanical power to electrical power. Explain the factors that determine the maximum power output of an ac generator, and the effect of these factors in rating generators. Explain the underlying principle and working of an. The plots of current and voltage across the capacitor as a function of time are shown in figure.
Subramanian, post graduate teacherphysics, government higher secondary school, manali, chennai 600 068, tamil nadu state, india. Ac stands for alternating current, meaning voltage or current that changes polarity or direction, respectively, over time. Generator is a machine that converts mechanical energy into electrical energy. If an electric current is passed through this wire, which direction will the wire be pushed by the interaction of the magnetic fields. Basic principle behind the working of an ac synchronous generator is also faradays law of electrical induction, somewhat similar to working of a dc generator. Jan, 2019 before we can explain the working principle of a dc generator, we need to cover the basics of generators. Module 7 basic ac theory this module describes the basic concepts of alternating current ac electrical circuits and discusses the associated terminology.
Rotating armature generator in the rotating armature ac generator as illust rated in figure 1, the stator provides a. Question 1 if an electric current is passed through this wire, which direction will the wire be pushed by the interaction of the magnetic fields. Nov 05, 2015 ac power alternating current generation explained duration. To understand how these generators operate, the basic theory of operation must first be understood. A visual aid to understanding the interaction of the two magnetic fields is a diagram showing the lines of flux emanating from the permanent magnets, against the circular lines of flux around the wire. Ac synchronous generator alternator construction and. Completely updated to reflect the 2017 national electrical code. The book begins with an overview of the primary components of. The fundamentals of ac generators training course is a comprehensive hands on classroom course that provides an introduction to the inner workings of alternators manufactured by cummins generator technologies. The positive end of the battery is always positive relative to the negative end, and the negative end of the battery is.
Alternating current is the form in which electric power is delivered to businesses and residences, and it is the form of electrical energy that consumers typically use when they plug kitchen appliances, televisions, fans and electric. It is the cosine of the phase angle between the voltage waveform and the current waveform assuming sinusoidal waveforms. Ac generators ac generator theory ac generator theory ac generators are widely used to produce ac voltage. Basic generating principles are most easily explained through the use of the elementary ac generator. Suppose an induction motor were built to run on singlephase ac power rather than polyphase ac power. Electrical theory alternating current direct current. Ac generator theory ac generators therefore, the equivalence of these units is expressed with a conversion factor as follows. A dc generator is more complex than an alternator, however, and contains additional components that can wear out over time. Both dc and ac generators convert mechanical power to electrical power. Ac generator works on the principle of electromagnetic induction. Ac and dc motor design follows respective generator design principles very closely. Ac generator theory worksheet ac electric circuits.
When a closed coil is rotated in a uniform magnetic field with its axis perpendicular to the magnetic field, the magnetic field lines passing through the coil change and an induced emf and hence a. This relationship between flux and induced voltage is expressed in faradays equation v n d. Is this an example of an electric motor or an electric generator. The coil is located between the poles of two permanent magnets. Thus, the voltage provided by a flashlight battery remains steady at about 1. When a closed coil is rotated in a uniform magnetic field with its axis perpendicular to the magnetic field, the magnetic field lines passing through the coil change and an induced emf and hence a current is set. Ohms law yields v c ix c, where v c is the rms voltage across the capacitor and i is the rms current in the circuit consider a circuit with only an inductor and an ac generator. Ac electromechanical generators, known as alternators, are of simpler construction than dc electromechanical generators. Basic electricity dover books on electrical engineering.
The voltage in a directcurrent circuit must be constant, or at least relatively constant, to keep the current flowing in a single direction. An electric current that flows continuously in a single direction is called a direct current, or dc. How does an ac synchronous generator or alternator work. The course material expands on basic ac electricity and magnetism theory to provide a complete understanding of alternator operation. Providing this motion requires that either a magnetic field is generated and a wire coil is rotated within it, or a magnetic field is. Whatever may be the types of generators, it always converts mechanical power to electrical power. Notes on ac generator or ac dynamo grade 12 physics. An alternator is a specific type of generator, so it is common and correct to refer to an alternator as a generator. Basically, an ac generator is an electrical machine that converts mechanical energy into electrical energy in the form of alternating current ac. Module 8 ac reactive components this module describes inductance and capacitance and their effects on ac circuits. Ac generators ac generator theory 5 ac generator theory ac generators are widely used to produce ac voltage. To understand how these motors operate, a knowledge of the basic theory of operation of ac motors is necessary. Nikola teslas ac dynamoelectric machine ac electric generator in an 1888 u.
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