Dc generators are classified based on how their fields are excited i. Nptel, online courses and certification, learn for free. This page on ac generator vs dc generator describes basic difference between ac generator and dc generator types. Dc generator or direct current generator generates a voltage when speed and flux.
Separately excited dc generators are rarely used in practice. C machines are worked out not only to solve the problems only but also to bring out important features of the motors. Multiple choice questions with answers on dc generators set 08 mcq dc generators edit practice test. Nptel provides elearning through online web and video courses various streams. Applications of dc generators that surround us everywhere. Generator 1 generator 2 system load 3 phase switch synchronizing lamps figure 41 connecting a generator to a bus the above figure 41 illustrates a generator g1 which is already connected to a. The commutator in a dc generator replaces the slip rings of the ac generator. The synchronous electrical generator also called alternator belongs to the family of electric rotating machines. Principle of operation of dc motors, types of dc motors. It works based on principle of faraday law of electromagnetic induction.
A device would be known as a generator if it convert mechanical energy into electrical energy, or as a motor if it does the other way. Must watch it subscribe our electrical engineering related channel electrical academy to get the. Nptel transformers video lectures, electrical machines lectures, dc machines video, nptel video lectures, nptel online courses, youtube iit videos nptel courses. C machine performance center around two fundamental equations namely the emf equation and the torque. A dc generator is an electrical machine which converts mechanical energy into direct current electricity. Generator working principle and explain about ac and dc. Bee1101 1 st and 2 nd semester syallabus modulei 10 hours dc networks. It is important to note that the name plate kw or hp rating of a d. Due to residual magnetism there will be a small initial voltage across the armature that is why the curve started from a. Electrical machinesi nptel online videos, courses iit. The rotor rotates because the wires and magnetic field of the motor are arranged so that a torque is developed about the rotors axis.
A compound dc generator has an armature resistance of 0. Armature reaction in a generator results in a demagnetization of leading. Ohms law and kirchhoffs laws, analysis of series, parallel and series parallel circuits. November 4, 2016 11 of 21 the test setup the dc machine to be tested and the dynamometer have already been placed on the bench and. An emf voltage is induced in a conductor if it moves through a magnetic field. In this video, construction of dc machines with all the parts are conceptually explained.
Armature reaction, separately excited and self excited generators, load characteristics of shunt, principle of operation, speed control of d. The alternator is smaller in size and requires less space whereas the generator requires large space. A typical alternator is shown in figure 33, view a. Multiple choice questions with answers on dc generators. Basic electrical engineering pdf free download bee notes pdf. 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. Dc machine are the electromechanical energy conversion devices which converts either dc power to mechanical power or mechanical power to dc power. This article outlines basic construction and working of a dc generator. The above content is the basic working principle of dc generator, explained by single loop generator model. Generator is a machine that converts mechanical energy into electrical energy. Introduction to dc generator generator is machine that converts mechanical energy to electrical energy.
Dc generator theory worksheet dc electric circuits. Types of dc generators diagrams included electrical4u. Rotating dc motors and linera dc motors class lecture notes pdf download. Direct current is the unidirectional current where the. Electrical machines 1 pdf notes em 1 pdf notes smartzworld. A dc power supply is used in most of the appliances where a constant voltage is required. These are generators in which the field winding is excited by the output of the generator itself. This is a problem in dc power systems, as the generator will act as a load, drawing energy from. The positions of the brushes of dc generator are so that the change over of the. To know how to estimate and predict efficiency of a d. A rotating armature coil passes through a magnetic field that develops between the north and. Mod01 lec26 lecture26separately excited dc generators. The principle of operation of a dc generator is similar to that of the ac generator, which was discussed previously.
Ac generator vs dc generatordifference between ac generator and dc generator. Umanand, principal research scientist, power electronics group, cedt, iisc bangalore. Dc machines 1 dc machines transformsmechanicalenergyintoelectric energywithdc voltage and current dc generatoror dynamo, or conversely dc motor. Be it motor or generator operations, the analysis of d. Current is supplied to the rotating armature winding through commutator. Dc generators will act as dc motors if connected to a dc power source and not spun at a sufficient speed. Mod01 lec21 lecture21operating principles of dc machines. Dc machines 1 dc machines transformsmechanicalenergyintoelectric energywithdc voltage and currentdc generatoror dynamo, or converselydc motor. Principle of operation of dc machines, types of dc generators. Dc machines voltage buildup and load characteristics.
A device would be known as a generator if it convert mechanical energy into electrical energy, or as a motor if it does the other way around from electrical to mechanical. 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 in dc machines, the field winding is wound onto the stator, while the armature winding is located on the rotor. Other members of the family are the directcurrent dc motor or generator, the induction.
Massachusetts institute of technology department of electrical engineering and computer science 6. These notes has been made by me after watching nptel lectures given by dr. This energy conversion is based on the principle of production of dynamically induced emf. The two segments of the split metal ring are insulated from each other. Principal of electrical machinery and optimization of. The elementary dc generator a singleloop generator with each terminal connected to a segment of a twosegment metal ring is shown in figure 14. Losses and torque equation, losses and efficiency calculation in d.
C generators may be classified as i separately excited generator, ii shunt generator, and iii series generator and iv compound generator. Different types of dcdc converters and its advantages. Dc generator characteristics and introduction to dc motors. Debaprasad kastha, department of electrical engineering, iit kharagpur. Generators principle ofoperationdc generator converts mechanical energy intoelectrical energy. Single phase induction motor, theory of operation double revolving field theory, equivalent circuit, determination of parameters methods of starting, split phase. Kirchhoffs laws, node and mesh analysis, deltastar. Dc machines are usually classified on the basis of their field excitation. Electrical engineering electrical machines i nptel. Basic electrical engineering pdf notes bee pdf notes. There are three methods of excitation, and thus three main types of dc generators permanent magnet dc.
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