Explain the underlying principle and working of an. Explain the operation of multiphase ac generators and compare with singlephase. Therefore, when running as a generator, the machine takes reactive power from the ac power line and supplies active power back into the line. Reactive power is needed for producing rotating magnetic field. 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. A dc generator produces direct power, while an ac generator produces alternating power.
The gas turbine converts the f76 fuel into mechanical power. Much like a dc generator, an ac generator requires a coil to cut across the force lines of a magnetic field. Fundamentals of ac generators 6241 cummins training. The generators ac output voltage can be transferred from the slip rings through the brushes to an external circuit. Notes on ac generator or ac dynamo grade 12 physics. An electric generator works on the principle of electromagnetic induction. To understand how these generators operate, the basic theory of operation must first be understood.
Each atom consists of an equal number of protons positive and electrons negative. Figure shows the plots of the current and voltage as a function of time for the inductor. Alternating current ac is an electric current which periodically reverses direction, in contrast to direct current dc which flows only in one direction. 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.
Refrigerator, washing machines, oven, lights, fan etc. The basic parts of an ac generator are the mechanical power, the magnets and one or more rotors. A dc generator is more complex than an alternator, however, and contains additional components that can wear out over time. Providing this motion requires that either a magnetic field is generated and a wire coil is rotated within it, or a magnetic field is. Ac motors are widely used to drive machinery for a wide variety of applications. Ac generators, also known as alternators, is a machine that converts mechanical energy into alternating electrical energy. Ac power, what would a magnetic compass do that was placed in the center. Generator working principle and explain about ac and dc. These generators are generally maintenance free, because of absence of brushes. An electrical machine used to convert mechanical energy into electrical energy is called a.
There are two types of generators dc generators and ac generators. The synchronous generator connection with wind turbine is shown in fig. An electrical generator is a device that converts mechanical energy to electrical energy. The main advantage of ac is ease of power distribution. It consists of a rectangular coil of wire which can be rotated about an axis. The elementary generator the simplest elementary generator that can be built is an ac generator. Now consider an ac circuit consisting only of a capacitor and an ac generator. 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. 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. Various types of alternating current generators are utilized today. The synchronous electrical generator also called alternator belongs to the family of electric rotating machines. The process is known as electricity generation and is analogous to a water pump.
Instead of multiple sets of windings, it only has one set of windings. 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. However, all electric power systems to which industrial generators are connected are threephase systems. Thus, the voltage provided by a flashlight battery remains steady at about 1. Ac generator theory worksheet ac electric circuits. All of our household appliances runs on ac current. 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. 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. The direction of the lines of force is given by the law of the screwdriver. The active power supplied back in the line is proportional to slip above the synchronous. Electrical theory alternating current direct current. The coil is located between the poles of two permanent magnets.
Note again that the voltage and current are not in phase. Nikola tesla was born an ethnic serb in the village smiljan, lika county, in the austrian empire present day croatia, on 10 july o. 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. Introduction there are two types of generators, one is ac generator and other is dc generator. To understand how these motors operate, a knowledge of the basic theory of operation of ac motors is necessary. Ac power alternating current generation explained duration. The course material expands on basic ac electricity and magnetism theory to provide a complete understanding of alternator operation. Rotating armature generator in the rotating armature ac generator as illust rated in figure 1, the stator provides a. It works based on principle of faraday law of electromagnetic induction. Explain the factors that determine the maximum power output of an ac generator, and the effect of these factors in rating generators. 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. 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.
Ac generator works on the principle of electromagnetic induction. Compare the types of rotors used in ac generators, and the applications of each type to different prime movers. As the coil sides a and b are rotated by an external force side a will have an emf induced first in one direction and then in the other direction. These different behaviors, described below, lead to different responses in ac circuits. Ac generator theory ac generators therefore, the equivalence of these units is expressed with a conversion factor as follows. Module 8 ac reactive components this module describes inductance and capacitance and their effects on ac circuits. The wire will be pushed up in this motor example notes.
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. Mileaf, harry, electricity one seven, revised 2nd edition, hayden book company. The book begins with an overview of the primary components of. Is this an example of an electric motor or an electric generator. Ac generators ac generator theory ac generator theory ac generators are widely used to produce ac voltage.
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. If an electric current is passed through this wire, which direction will the wire be pushed by the interaction of the magnetic fields. A governor connected to the prime mover regulates its speed and controls the amount of mechanical power transmitted to the generator. It is a device which converts mechanical energy into alternating form of electrical energy. Generator is a machine that converts mechanical energy into electrical energy.
Some materials called conductors have loosely held electrons that can flow. Introduction to basic notions on electric power 5 electric current conductor lines of force fig. Electric generator class 10 working, principle, diagram. 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. Nov 05, 2015 ac power alternating current generation explained duration. Without any of these parts, electricity cant be produced. Kingsley, electric machinery, mcgrawhill book company, inc. 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. Industrial solar pv facilities use dc ac converters, again not perfectly e cient, to make their power saleable. Ac generator has slip rings while the dc generator has a commutator. The theory of operation is explained and the transient and steady state. Therefore any discussion in this book about the power. View answer ncert question 6 b state whether the following statements are true or false.
Ac generator theory ac electric circuits pdf version. 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. An ac generator, or alternator, is used to produce ac voltages for transmission via the grid system or, locally, as portable generators. Synchronous generator an overview sciencedirect topics. Completely updated to reflect the 2017 national electrical code. The basic principle of an ac generator is shown in figure 1. His father, milutin tesla 18191879, was an eastern orthodox priest. Cbse ncert notes class 12 physics electromagnetic induction. 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. Ac stands for alternating current, meaning voltage or current that changes polarity or direction, respectively, over time. Jan, 2019 before we can explain the working principle of a dc generator, we need to cover the basics of generators.
Nikola teslas ac dynamoelectric machine ac electric generator in an 1888 u. Basic generating principles are most easily explained through the use of the elementary ac generator. Both dc and ac generators convert mechanical power to electrical power. Power factor is a dynamic value between 0 and 1 which depends on the operating conditions of the ac circuit. 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. The positive end of the battery is always positive relative to the negative end, and the negative end of the battery is. Whenever the magnetic flux changes an emf will be induced in the coil. This relationship between flux and induced voltage is expressed in faradays equation v n d. Whatever may be the types of generators, it always converts mechanical power to electrical power. The basic function of a generator is to convert motion into electricity. Ac generators ac generator theory 5 ac generator theory ac generators are widely used to produce ac voltage. Generators, dc motors, ac theory, ac power, ac generators, voltage. Ac synchronous generator alternator construction and.
An alternator is a specific type of generator, so it is common and correct to refer to an alternator as a generator. Subramanian, post graduate teacherphysics, government higher secondary school, manali, chennai 600 068, tamil nadu state, india. Alternating current generators, typically referred to as ac generators, generally work on the same principle as direct current generators. The generator in turn converts the mechanical power to electrical power. Module 7 basic ac theory this module describes the basic concepts of alternating current ac electrical circuits and discusses the associated terminology. The types discussed in the following paragraphs are typical of the more predominant ones in use. The plots of current and voltage across the capacitor as a function of time are shown in figure. An electric current that flows continuously in a single direction is called a direct current, or dc. It works on the principle of electromagnetic induction i. Learn the essentials of electrical grounding and bonding.
Basically, an ac generator is an electrical machine that converts mechanical energy into electrical energy in the form of alternating current ac. The generation of alternating currents ac is based on the phenomenon of electromagnetic induction. 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. Suppose an induction motor were built to run on singlephase ac power rather than polyphase ac power. How does an ac synchronous generator or alternator work. View answer ncert question 16 the essential difference between an ac generator and a dc generator is that. It is the cosine of the phase angle between the voltage waveform and the current waveform assuming sinusoidal waveforms. For this reason, the ac generator will be discussed first. Industrial solar pv facilities use dcac converters, again not perfectly e cient, to make their power saleable.
761 863 586 1136 120 906 5 915 219 730 830 632 900 760 31 1249 1039 584 1191 83 345 702 371 1495 1354 911 1495 1160 1164 533 1470 1023 349 92 1220 604 1074 451 330 1454 973