Ppt dc generators ppt powerpoint presentation free to. The dc generator as we know can be either separately excited or self excited in shunt. The generator is driven at its rated speed with the help of prime mover dc motor. The external and internal characteristics of the given dc shunt generator were obtained. So as it is connected in shunt it has constant characteristics. In this experiment we aim to conduct a noload test on a dc generator to determine its open circuit characteristics followed by a load test on a dc shunt generator to determine its external load characteristics.
Open circuit characteristics of separately excited dc generator. E is fewer than e 0 due to the demagnetizing effect of armature reaction. The most important characteristics of a dc generator are as follows. Discussion a dc motor generator can run either as a motor or as a generator. The open circuit characteristic is one of the dc generator characteristics which is practically same for all dc generators. Experiment 3 performance characteristics of dc generators 11. Noload saturation or open circuit characteristic e o i f. Study of separatelyexcited dc shunt generator objectives 1. It consists of the same basic elements as a simple ac generator like the multiturn coil rotating uniformly in a magnetic field. Open circuit characteristics of a dc generator aim 1 theory.
C generators may be classified as i separately excited generator, ii shunt generator, and. The field winding of the dc generator series or shunt is disconnected from the machine and is separately excited from an external dc source. Geethanjali college of engineering and technology department electrical and electronics engineering list of experiments s. I external and internal characteristics of dc shunt generator. To study the properties of the separatelyexcited dc shunt generator under noload and fullload. This characteristic shows the relation between generated emf at no load e 0 and the field current i f at a given fixed speed. The induced emf in the armature winding of a dc machine. In this chapter, the authors highlight the types and characteristics of dc generator. Determination of operation characteristics of a synchronous generator by static experimental tests article pdf available in advances in electrical and computer engineering 162. The curve can be deduced from the noload saturation curve provided the values of armature.
Load characteristics of dc compound generator with differential and cumulativeconnections. Magnetic or open circuit characteristic of series wound dc generator. Shunt dc generator and its load characteristics slideshare. A direct current dc generator, not using a permanent magnet, requires a. Open circuit characteristic is the relation between the noload generated emf in the armature, and the field exciting current at a fixed speed. External characteristics via 61 critical resistance for shunt generator. C of a dc shunt generator and to determine its critical resistance. Pdf determination of operation characteristics of a. When you have completed this experiment, you should be able to. Compound wound dc generator this type of dc generator has both series and shunt field windings. There are generally three most important characteristic of dc generator.
Jul 30, 2015 characteristic of separately excited dc generator magnetic or open circuit characteristic the curve which gives the relation between field current if and the generated voltage e0 in the armature on no load is called open circuit characteristics the plot of this curve is practically same for all types of generators, whether they. Dc generator external characteristics of shunt generator 2 theory 2. Characteristics of dc generators in this video we will study about different types of characteristic for different types of dc generator. Pdf principles of electrical machines book by vk mehta and.
Open circuit characteristic or magnetization curve or no load saturation curve. Scott connection with balanced and unbalanced loads. Vv open delta and determination of efficiency and regulation under balanced resistive load. The load characteristics of the given separately excited dc generator was obtained. For open circuit test 10% of rated full load current theory. The book principles of electrical machines book by vk mehta and rohit mehta is an ideal text for students who look to gain a current and clear understanding of the subject as all theories and concepts are explained with lucidity and clarity. Critical field resistance is a term that is associated with a dc shunt generator. The arrangement for obtaining the necessary data to plot this curve is shown in fig. Open circuit characteristics of a dc generator aim to obtain open circuit or magnetization characteristics of dc generator 1 theory 1. To determine experimentally the magnetization or open circuit characteristics of a d. Dc generator characteristics in general, two characteristics specify the steadystate performance of a dc generators. Please go through the construction of dc generator before reading this article about different types of dc generator a dc generator requires mmf to establish flux in its magnetic circuit. The exciting or field current if is obtained from an external independent d. It shows the steady state characteristic of dc generators.
Noload saturation characteristic e0if it is also known as magnetic characteristic or opencircuit characteristic o. E 0 i f open circuit characteristic is also known as magnetic characteristic or noload saturation characteristic. We discuss the terminal characteristics of separately excited dc generator find the summary as pdf at. It should be noted that shunt generator will build up voltage only if field circuit resistance is. Characteristic of dc generators separately excited self. Open circuit and load characteristics of dc shunt generator critical resistance and critical speed. Click here to download the pdf of this topic characteristics of dc. Generator characteristics 969 ii load saturation curve vifthe curve showing relation between the terminal voltage v and field current if when the genera tor is loaded, is known as load saturation curve. To obtain the armature voltage vs armature current load curve of the generator. Dc voltmeterammeter, connect the circuit shown in figure 2. There are generally three most important characteristics of series wound dc generator which show the relation between various quantities such as series field current or excitation current, generated voltage, terminal voltage and load current.
Characteristic of dc generators separately excited self excited and compound generator characteristic is the graph between the two dependent quantities. The generator field excitation is adjusted to get the rated noload voltage on open circuit. Aug 03, 2018 there are generally three most important characteristics of series wound dc generator which show the relation between various quantities such as series field current or excitation current, generated voltage, terminal voltage and load current. Open circuit test and short circuit test of synchronous. Characteristic of separately excited dc generator electrical4u. These characteristics of dc generators are explained below. Dc generator characteristics it can be seen from the external characteristics that the terminal voltage falls slightly as the load current increases. Open circuit and load characteristics of dc shunt generatorcritical resistance and critical speed. External characteristic of dc compound wound generator is drawn between the terminal voltage and the load current. It shows the relation between the noload generated e. Magnetic or open circuit characteristic of separately excited dc generator t.
The open circuit characteristics for a dc generator are determined as follows. Characteristics of dc generator the three most important characteristics of curves of a d. Voltage regulation of an alternator by emf and mmf. Generators following are the three most important characteristics or curves of a d. For this reason, the ac generator will be discussed first. Experiment 5 power transformer open and short circuit tests 24. Dc generator or direct current generator generates a voltage when speed and flux are met. Characteristic of dc compound wound generators electrical. Open circuit test of synchronous machine is also called no load, saturation or magnetizing characteristics for the reason which will be clear after going through the post. The open circuit terminal voltage versus the field current for a separately excited dc generator with provided the following test data at revolving speed 1400 rpm as show by the. Generator characteristics the following are the three most important characteristics of a d. Characteristics of dc compound motor dc compound motors have both series as well as shunt winding. The occ of even selfexcited dc generator is obtained by running it as a separately excited generator. Separation of hysteresis and eddy current losses in single phase transformer.
Construct an equivalent circuit of a transformer on no load predict the efficiency of a transformer over a range of loads. The three important characteristics of dc generator are. Aug 03, 2018 there are generally three most important characteristic of dc generator. There are several types of direct current machines. The mmf necessary to establish flux in the magnetic circuit of a dc generator is obtained by field excitation.
Electrical and electronics engineering lab manual pdf eee lab manual pdf. And determine the full load regulation of a three phase synchronous generator by synchronous impedance method. Jun 30, 2017 a dc generator is an electrical machine which converts mechanical energy into direct current electricity. Laboratory practice there are four core electrical engineering laboratories, beginning with ee 291.
State the term that applies to voltage variation from noload to fullload. No load and load characteristics of dc shunt generator. The following are the three most important characteristics in a d. In this type of generator, direct current from a separate source is passed. This characteristic shows the relation between generated emf at no load e0 and the field current if at a given fixed speed. The handoperated field rheostat, shown in figure 121, is a typical example of manual voltage. Principal of electrical machinery and optimization of. This curve shows the relation between the generated e. The curve which gives the relation between field current i f and the generated voltage e 0 in the armature on no load is called magnetic or open circuit characteristic of a dc generator. Pdf 3generator characteristicssa shomi ahmed academia. Jul 08, 20 dc generator characteristics opencircuit and load characteristics the terminal voltage of a dc generator is given by aa mf aaat ri dropreactionarmatureif riev.
Laboratory manual electrical engineering laboratory iv part a. The buildup of voltage in a selfexcited generator can be explained referring to fig. Experiment the open circuit characteristics of a separately excited dc generator with the field variation at different speed studying load characteristics of dc shunt generator observing and record the behaviour the dc cumulative compound generator under loading conditions introduction. Open circuit test and short circuit test are performed on a synchronous machine to find out the synchronous impedance for large machine to determine the voltage regulation open circuit test the alternator is run at rated synchronous speed and the load terminals are kept open. Aim to determine the magnetization open circuit characteristics of dc shunt generator, the critical field resistance and critical speed. These characteristics show at a glance the behaviour of the generator under different load conditions. Mar 26, 2015 the three important characteristics of dc generator are. The curve represents the relation flanked by the generated e. How to draw the curve of characteristic of a separately. Generator is machine that converts mechanical energy to electrical energy. Other members of the family are the directcurrent dc motor or generator, the induction motor or generator, and a number. In permanent magnet dc machines, a permanent magnet is used to establish flux in the magnetic circuit.
Introduction to dc generator and study of dc shunt generator and load characteristics of dc shunt generator. A shunt generator is a type of direct current electric generator in which field winding and armature winding are connected in parallel, and in which the armature supplies both the load current and the field current. The following data are taken from the open and short circuit characteristics of a 45kva, threephase, yconnected, 220v linetoline, sixpole, 60hz synchronous machine. They essentially capture the saturation characteristics of the machine which. To build up voltage of a shunt generator, the generator is driven at the rated speed by a. Swinburnes test and speed control of dc shunt motor. Characteristics of series wound dc generator electrical4u. C open circuit characteristic is also known as magnetic characteristic or noload saturation characteristic. Therefore, this curve will lie under the open circuit characteristic o. Dec 25, 2017 merry christmaswe discuss the basic definition of different types of dc generator, and also the equivalent circuit of a dc generator.
These generators are not found in industrial applications because of the low power generated from it. Characteristics of dc generators characteristic of dc. To study the properties of the separatelyexcited dc shunt generator under noload and fullload conditions 2. Open circuit test and short circuit test are performed on a synchronous machine to find out the parameters of synchronous machine and hence to have an idea of their performance. Magnetic or open circuit characteristic of separately excited dc generator. C shunt generator and to determine the critical field resistance and critical speed. Lab5 the dc selfexcited shunt generator objective 0 to. Determination of critical field resistance critical speed. The characteristic of the dc generators explain the relations between the loads, excitation and terminals voltage through graph. On plotting the relation between e0 and if, we get the open circuit characteristics. Join our community just now to flow with the file dc generator and make our shared file collection even more complete and exciting. Electrical and electronics engineering lab manual pdf. Laboratory manual electrical engineering laboratory. In a compound motor, if series and shunt windings are connected such that series flux is in direction as that of the shunt flux then the motor is said to be cumulatively compounded.
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