The two segments of the split metal ring are insulated from each other. Learn for free, pay a small fee for exam and get a certificate. Working principle of dc generator introduction to dc generator. Debaprasad kastha, department of electrical engineering, iit kharagpur. Power systems are highly interconnected and many generators share the load. Mod01 lec26 lecture26separately excited dc generators. With larger amounts of power, a great deal more current flow occurs through the slip rings and brushes. Be it motor or generator operations, the analysis of d. These notes has been made by me after watching nptel lectures given by dr.
Induction generators are also called as asynchronous generators. Transients in rl, rc and rlc circuits with dc excitation. Due to residual magnetism there will be a small initial voltage across the armature that is why the curve started from a point a which is a little way up to the origin o. Pdf ee6504 electrical machinesii emii books, lecture. It can also be obtained from a dc generator where the generated ac is converted into dc by commutator and brush assembly or by semiconductor rectifiers. The active power supplied back in the line is proportional to slip above the synchronous. Solar cells, batteries and thermocouples are the sources of. Aug 03, 2018 p number of poles in the dc generator. The above content is the basic working principle of dc generator, explained by single loop generator model.
Mod01 lec29 lecture29interconnected dc generators mod01 lec30 lecture30characteristics of dc shunt motors mod01 lec31 lecture31starting of dc shunt motors. Explain the effect of motor reaction in a dc generator. 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. Laminations of core are generally made of a case iron b carbon c silicon steel d stainless steel ans. These 3systems were highly used between 1920 e 1960 3. Bee1101 1 st and 2 nd semester syallabus modulei 10 hours dc networks. Current is supplied to the rotating armature winding through commutator segments.
Sep 02, 2014 which of the following components of a d. This article outlines basic construction and working of a dc generator. 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. Generator protection introduction size of individual generating unit 30 mw to 500 mw loss of even a single unit is a serious problem consequence. Methods for speed control of dc motors and applications of dc motors v. Armature reaction, separately excited and self excited generators, load characteristics of shunt, principle of operation, speed control of d.
Dc generators are classified based on how their fields are excited i. Separately excited dc generators field coils excited by some external source. Applications of dc generators nowadays cheap and economical rectifiers and filters grant a new life to dc generators and give them a great importance in all fields around us and it also leads to diversity so there are many types of dc generators which we illustrated and which has many applications and thats what we will explain today. Dc machines complete course includes fundamentals, motors.
Dc systems show some disadvantages with the increase of generators nominal power. Nptel electrical engineering electrical machines i. A dc generator is an electrical machine which converts mechanical energy into direct current electricity. Electrical machines 1 pdf notes em 1 pdf notes smartzworld. Batteries, solar cells, thermocouples and fuel cells are the source of dc power. Abb network partner ab generator protection 1mrk 502 003aen page 7 4 protective relays for generators and generator transformer units fig. Generator control and protection generator protection g 64f 60 51n 24 87t 81u 47 62 27 87g 59 81o 321 59n 51gn 322 273n 40 51v 50 ie 46 49 63 reg 51 51 25. Ee6504 electrical machinesii em ii syllabus unit i synchronous generator constructional details types of rotors winding factors emf equation synchronous reactance armature reaction phasor diagrams of non salient pole synchronous generator connected to infinite bussynchronizing and parallel operation synchronizing torque change of excitation and mechanical input. Lecture series on basic electrical technology by prof.
Just like a dc machine, a same induction machine can be used as an induction motor as well as an induction generator, without any internal modifications. C machine performance center around two fundamental equations namely the emf equation and the torque. Magnetic or open circuit characteristic of separately excited dc generator the curve which gives the relation between field current i f and the generated voltage e 0 in. In a separately excited dc generator, the field winding is excited by an external independent source. Different types of dcdc converters and its advantages. For a beginner, it is suggested to follow the following. Internal characteristic of series wound dc generator.
Dc machine are the electromechanical energy conversion devices which converts either dc power to mechanical power or mechanical power to dc power. Dc machines 1 dc machines transformsmechanicalenergyintoelectric energywithdc voltage and current dc generatoror dynamo, or conversely dc motor. For a beginner, it is suggested to follow the following guidelines for successful completion of the problem. These electrical machines em study notes will help you to get conceptual deeply knowledge about it. Nptel electrical engineering electrical machines ii. Nptel transformers video lectures, electrical machines lectures, dc machines video, nptel video lectures, nptel online courses, youtube iit videos nptel courses. L umanand department of power electronics group, cedt iisc bangalore. A recommended minimum of relays for different types and sizes of generators is given under section protective relay schemes. It is difficult and expensive to build slip rings and brushes to carry large amounts of current. Basic electrical technology nptel online videos, courses. This is the largest group of excitation models including eight models. In factories which need a large amount of current to produce aluminum, chlorine, and similar industrial materials. The output of the generator supplies ac to the load. C generators may be classified as i separately excited generator, ii shunt generator, and iii series generator and iv compound generator.
Before starting to explain how an induction asynchronous generator works, i assume that you know the working principle of an induction motor. Various types of losses that occur in dc machines and how to calculate efficiency vi. Types of dc generators diagrams included electrical4u. Here you can download the free lecture notes of analog communication system pdf notes ac notes pdf materials with multiple file links to download. Parallel operation of generators in modern power systems isolated generators are very rare. State the term that applies to voltage variation from noload to fullload conditions and how it is expressed as a percentage.
The positions of the brushes of dc generator are so that the change over of the segments a and b from one brush to other takes place when the plane of rotating coil is at a right angle to the plane of the lines of force. The synchronous electrical generator also called alternator belongs to the family of electric rotating machines. Therefore, when running as a generator, the machine takes reactive power from the ac power line and supplies active power back into the line. The commutator in a dc generator replaces the slip rings of the ac generator. Dc generator characteristics and introduction to dc motors. Nptel, online courses and certification, learn for free. You have remained in right site to start getting this info. Characteristics of generators and parallel operation of generators iv. These systems do not allow negative field current and only ac4a model allows negative field voltage forcing. Dc stands for direct current, in which the current flow is unidirectional. Basic ac electrical generators 5 rotating armature ac generators are typically used in applications involving small amounts of power. In a separately excited generator field winding is energised from a separate voltage source in order to produce flux in the machine. Kirchhoffs laws, node and mesh analysis, deltastar and stardelta transformations.
Electrical machines study notes handwritten pdf free stuff. Basic electrical technology basic electrical technology. It is first explained that two torques namely the driving torque and the load torque will exist during the operation of the machine both as generator and motor. The process of dc conversion can be don be dc converters. Self excited dc generators field coils excited by the generator. A rotating armature coil passes through a magnetic field that develops between the north and. Although the motion of the conductor is rectilinear, the example brings out several useful facts which are true for rotating machines as.
C machines are worked out not only to solve the problems only but also to bring out important features of the motors. There are three methods of excitation, and thus three main types of dc generators. Let us suppose there are z total numbers of conductor in a generator, and arranged in such a manner that. Synchronous generator operation notes ebook free download pdf. Apr 01, 2008 lecture series on basic electrical technology by prof. Hi friends, this playlist contains dc machinery fundamentals, dc generator and dc motors, these videos cover most of the concept that will need in understand the dc. The phenomena of armature reaction and commutation iii. These are generators in which the field winding is excited by the output of the generator itself. Now, according to faradays law of induction, the induced emf of the armature conductor is denoted by e which is equal to rate of cutting the flux.
Each commutator segment also located on the rotor is connected to an armature winding coil. There are generally three most important characteristic of dc generator. Electrical engineering electrical machines i nptel. If the dc generator is excited using an external source, this is made with a permanent magnet generator pmg. Ac type of excitation systems contains ac generator and either stationary or rotating rectifier to produce direct current needed for generator excitation. Working principle of dc generator why are you interested in dc generator. A dc power supply is used in most of the appliances where a constant voltage is required.
An emf voltage is induced in a conductor if it moves through a magnetic field. Because it is only an electrical device which converts mechanical energy into electrical energy. A force is induced in a conductor that has a current going through it and placed in a magnetic field any dc machine can act either as a generator or. Dc machines voltage buildup and load characteristics. There are three methods of excitation, and thus three main types of dc generators permanent magnet dc generators field coils excited by permanent magnets. As soon as we supply direct current in the armature, a mechanical force acts on it due to the electromagnetic effect. Pdf analog communication system pdf notes ac notes sw. Protection systems of such generators have also become more stringent required to reduce the outage period to a minimum achieved by rapid discriminative clearance of all fault. Nptel provides elearning through online web and video courses various streams. Dc machines in dc machines, the field winding is wound onto the stator, while the armature winding is located on the rotor. Reactive power is needed for producing rotating magnetic field. For electrochemical processes, charging of battery, operation of electronic circuits etc. Nptel syllabus pulse width modulation for power electronic converters video course course outline converter topologies for ac dc and dc ac power conversion, overview of applications of voltage source converters.
As described before there are three types of selfexcited dc generators they. C, generator plays vital role for providing direct current of a d. Bookmark file pdf nptel basic electrical engineering recognizing the pretension ways to get this books nptel basic electrical engineering is additionally useful. Applications of dc generators that surround us everywhere. This energy conversion is based on the principle of production of dynamically induced emf. Analog communication pdf notes book starts with the topics covering introduction ac, dsb modulation, ssb modulation, angle modulation concepts, angle modulation methods, noise etc. The elementary dc generator a singleloop generator with each terminal connected to a segment of a twosegment metal ring is shown in figure 14. So long the machine operates in unsaturated condition the. Motors convert electrical power input power into mechanical power output power while generators convert. The only purpose for the dc exciter generator is to supply the direct current required to maintain the ac generator field.
Umanand, principal research scientist, power electronics group, cedt, iisc bangalore. Simple bock diagram g prime mover mechanical input threephase electrical output ia ib ic dc field source. Figure 32, view b, is a simplified schematic of the generator. Working or operating principle of dc motor electrical4u. The principle of operation of a dc generator is similar to that of the ac generator, which was discussed previously. A compound dc generator has an armature resistance of 0. Read the problem and note down the informations provided about the motor. Permanent magnet dc generators field coils excited by permanent magnets. Nptel video lectures, iit video lectures online, nptel youtube lectures. Electrical machinesi nptel online videos, courses iit. The very basic construction of a dc motor contains a current carrying armature, connected to the supply end through commutator segments and brushes. Separately excited dc generators are rarely used in practice. Mod01 lec21 lecture21operating principles of dc machines. The first problem of an engineer is connecting a synchronous generator on an existing bus.
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