Explain the constructional details of alternator in. Ge power systems ger4212 0801 2 ge generator rotor design, operational issues, and refurbishment options coupling coil slot retaining ring balance plug fan collector. According to the structure, it can be divided into two types. Synchronous generator, that is, an alternator ac generator with the same rotor speed as the rotating magnetic field of the stator. But the alternator conductors are calculated for a definite current and the insulation at magnetic system are designed for a definite voltage independent of p. The developed torque versus torque angle for a salientpole synchronous generator. Basic ac electrical generators 3 as the south pole moves away, the current in the winding decreases, returning to zero again when neither pole is close to the winding. By applying flemings right hand rule, current induces in conductor ab from point b to a and current induces in a conductor cd from point d to c. In my opinion, during the slip test the synchronous motor did not locked in that means it is an induction motor still. Slip test is performed on salient pole synchronous machine to determine the direct axisreactance and quadrature axis reactance.
The rotor of a synchronous machine is a large electromagnet. Slip test on 3phase alternator,ask latest information,abstract,report,presentation pdf,doc,ppt,slip test on 3phase alternator technology discussion,slip test on 3phase alternator paper presentation details. In this phasor diagram we have drawn the direction of the i a is in phase with that of the e f as per the point number 1 mentioned above. Ger4212 ge generator rotor design, operational issues. The machine armature is connected to a 3phase supply whose voltage is much less than the rated voltage of the machine, while the rotor is run at speed close to synchronous with the field winding left open. Two reaction theory of salient pole machines instrumentation. Blondels two reaction theory, phasor diagram, direct axis and quadrature axis synchronous reactances, power angle characteristics, slip test. May 11, 2020 chapter 4 synchronous generators or alternators notes, electrical machines, electrical engineeri ssc je notes edurev is made by best teachers of ssc je. The component f q results in a crossmagnetizing effect. Alternator synchronous generator and types of alternators.
Sep 08, 2015 in my opinion, during the slip test the synchronous motor did not locked in that means it is an induction motor still. The magnetic poles can be either salient sticking out of rotor surface or nonsalient construction. Eeeb344 electromechanical devices chapter 5 chapter 5. Performance of synchronous generator connected to infinite bus, under constant power. Salient pole synchronous motor power developed by a salient pole synchronous motor. Why salient pole synchronous machine are more stable than. One pole pitch is equals to 180 electrical degrees. Non salient or cylindrical pole type salient pole type. Electrical machines short answers instrumentation tools. The distance between the centres of two adjacent poles is called pole pitch.
Phasor diagram for synchronous generator electrical4u. A three phase, 12 pole, salient pole alternator is coupled to a diesel engine running at 500 rpm. A field coil is an electromagnet used to generate a magnetic field in an electromagnetic machine, typically a rotating electrical machine such as a motor or generator. Dec 18, 2018 a generator is a device that converts mechanical energy into electrical energy. In large machines, field windings consist of rectangular copper strip wound on edge. Explain the constructional details of alternator in detail.
Chapter 4 synchronous generators or alternators notes, electrical machines, electrical engineeri ssc je notes edurev notes for ssc je is made by best teachers who have written some of the best books of ssc je. Chapter 5 presents case studies to test the different parts of the new poleslip protection function, like the postfault voltage prediction and transient power angle calculations. On the other hand, in a salient pole machine as shown in the crosssectional view of fig. The rotor winding is provided on these poles and it. Direct and quadrature axis reactances of a salient pole synchronous machine can be estimated by means of a test known as the slip test.
The direct and quadrature axis components of current and reactance are same as defined earlier for the synchronous generators. A dynamic representation of a salient pole synchronous. In a rotating machine, the field coils are wound on an iron magnetic core which guides the magnetic field lines. This document is highly rated by ssc je students and has been viewed 855 times. As in a salient pole synchronous machine, air gap is not constant. Slip test measurement of direct and quadrature axis reactance and predetermination of regulation of salient pole synchronous machines. Apr 20, 2012 slip test is performed on salient pole synchronous machine to determine the direct axisreactance and quadrature axis reactance. To find xd and xq of a salient pole rotor type synchronous machine by slip test apparatus. The poles and poleshoes which cover 23 of polepitch are laminated to minimize heating due to eddy currents. Determination of load angle for salientpole synchronous machine. Synchronous generator construction and working principle. In a salient pole alternator, the reactance of magnetic circuit along is along its quad stator axis. Non salient pole rotors are cylindrical in shape having parallel slots on it to place rotor windings. Such that, the conductors ab and cd are under the npole and spole respectively.
The projected poles are made up from laminations of steel. Slip test on salient pole synchronous machine in brief. Can we find regulation of a salient pole machine by this test. Find the percentage slip and number of poles of the induction motor.
But the alternator conductors are calculated for a definite current and the insulation at magnetic system are designed for a. Synchronization of two three phase alternators, by a synchroscope method b three dark lamp method c two bright one dark lamp method 6. It is known as the direct axis or d axis component. The pole face is so shaped that the radial air gap length increases. The nps institutional archive theses and dissertations thesis collection 1955 a dynamic representation of a salient pole synchronous generator. Such generators get characterized by their large diameters and short axial lengths. It is a test done in alternator to measure the value of direct axis synchronous reactancexd and quadrature axis synchronous reactancexq. These two points are necessary for making the phasor diagram of synchronous generator. Ger4212 ge generator rotor design, operational issues, and. Thus, x d direct axis reactance x q quadrature axis reactance i d direct axis component of i a. Synchronous machines basic principle of operation, construction of salient and non salient pole synchronous machines, generated e.
While this simple gen erator produces ac alternating current, the current produced is not very large since the strength of the magnetic field is not very large. As the air gap is nonuniform, the reatance offered also varies and hence current drawn the armature also varies cyclically at twice the slip frequency. As discussed above the salient pole alternator turns at low speed, therefore, the number of poles required to be more. It consists of a coil of wire through which a current flows. The individual field pole windings are connected in series in such a way that when the field winding is energized by the d.
Slip test on synchronous machine linkedin slideshare. Mar 28, 2015 3 phase salient pole alternator by slip test for for angle between ia and io 3 phase salient pole synchronous generator calculations examples a 3. The d axis component of the armature mmf f a is denoted by f d and the q axis component by f q. It is also defined as the number of slots per pole. A brushless dc motor and pmsm motor consists of a permanent magnet, which rotates the rotor, surrounded by three equally spaced windings, which are fixed the stator. Apr 14, 2017 a salient pole synchronous machines has nonuniform air gap. So, the direction of current can be indicated as a d c b and direction of current for the previous.
In a salient pole synchronous machine two reaction model the flux established by a mmf wave is independent of the spatial position of the wave axis with respect to the field pole axis. Emf in the stator of a frequency of 1snetfrequency. Determination of x d and x q direct axis and quadrature axis reactances 4. On the other hand, in a salientpole machine as shown in the crosssectional view of fig. Experimental setup for dc decay test the standstill dc decay test consists in cutting off the c rform the test, the synchronous generator m, the switch s a is closed and the stator windings are e cedure starts from a mathematical m. What is the difference between salient pole alternator and cylindrical rotor type alternator. Intelipro an innovative new solution for pole slip duration. In salient pole type of rotor consist of large number of projected poles salient poles mounted on a magnetic wheel. A synchronous generator is a machine for converting mechanical power from a prime mover to a. Regarding salient pole machines, they are larger than cylindrical machines with comparable output. What is synchronous generator asynchronous generator. How is the regulation of alternator predetermined by slip test. Determination of load angle for salientpole synchronous.
They are smaller in diameter but having longer axial length. Non salient pole rotors are normally used for rotors with 2 or 4 poles rotor, while salient pole rotors are used for 4 or. Determination of xd and xq using slip test electrical idea. Salient pole machine, or effect of salient poles, or two reaction theory 2. Salient pole synchronous machine two reaction model. The component f d is either magnetizing or demagnetizing. It has a large number of projecting poles having their cores bolted or dovetailed onto a heavy magnetic wheel of cast iron or steel of good magnetic quality. Slip test on 3phase alternator,ask latest information,abstract,report,presentation pdf,doc,ppt, slip test on 3phase alternator technology discussion, slip test on 3phase alternator paper presentation details. Given below is the phasor diagram of synchronous generator. Voltage regulation of an alternator by emf and mmf methods.
Synchronising method, effect of wrong synchronising, load sharing between alternators in parallel. Procedure of synchroniation a dark lamp method b synchroscope c computerized synchronisation 6. The induced torque out of a salientpole generator as a function of the torque angle. It is done only on salient pole alternatorsnon uniform field. Speed and frequency in an alternator, there exists a definite relationship between the rotational speed n of the rotor, the frequency f of the generated e. What are the advantages of a round rotor generator than a. A makeshift solution is the claw pole generator, trading mechanical stability vs. The alternator is driven by auxiliary prime mover at a speed slightly less than the synchronous speed under these conditions. In this type, salient or projecting poles are mounted on a large circular steel frame which is fixed to the shaft of the alternator as shown in fig. Synchronous machines notes part2 electric equipment. The analysis of salient pole synchronous motor is based on the blondels two reaction. Assuming non salient pole alternator and neglecting losses.
Aug 08, 2017 to determine xd and xq of a salient pole synchronous machine. Jan 09, 2016 in a salient pole synchronous machine two reaction model the flux established by a mmf wave is independent of the spatial position of the wave axis with respect to the field pole axis. In fact, a given synchronous machine may be used, at least theoretically, as an alternator, when driven. The poles and pole shoes which cover 23 of pole pitch are laminated to minimize heating due to eddy currents. A dynamic representation of a salient pole synchronous generator. Dec 07, 2019 the speed of an alternator is given as n 120fp hence the speed of an alternator is inversely proportional to the number of poles. The theory proposes to resolve the given armature mmfs into two mutually perpendicular components, with one located along the axis of the rotor of the salient pole. Salient pole rotors have concentrated winding on the poles. Salient pole synchronous machine two rection theory. The construction of non salient pole rotor cylindrical rotor is as shown in figure above.
The magnetic poles can be either salient sticking out of rotor surface or non salient construction. They allow better ventilation the pole faces are so shaped that the radial air gap length increases from the pole center to the pole tips so that the flux distribution in the airgap is sinusoidal in shape which will help the machine to generate sinusoidal emf. Construction of a salient pole rotor is as shown in the figure at left. In fact, a given synchronous machine may be used, at least theoretically, as an alternator, when driven mechanically or as a motor, when driven electrically, just as in the case of d. Two reaction theory of salient pole machines 0% for obtaining maximum current when we conduct the slip test on a synchronous machine, its armature field will align along. Synchronous machines basic principle of operation, construction of salient and nonsalient pole synchronous machines, generated e. Two reaction theory salient pole synchronous machine.
It supplies an induction motor ich has a full load speed of 144wh 0 rpm. Alternator generator mcqs with explanatory answers. Now let us derive expression for the excitation emf in each case. Salient pole synchronous motor electrical engineering. To study and measure positive, negative and zero sequence impedance of a alternator 5. Chapter 4 synchronous generators or alternators notes. Two reaction theory salient pole synchronous machine two reaction theory was proposed by andre blondel. Non salient pole b stator windings or armature windings the rotor of a synchronous generator is a large electromagnet and the magnetic poles on the rotor can either be salient or non salient construction. Could you please send the pdf of this in my email address. Damper bars are usually inserted in the pole faces to damp out the rotor oscillations during sudden change in load condition as shown in fig. Thus, x d direct axis reactance x q quadrature axis reactance i d. The physical implementation of the new poleslip protection logics in an abb rem543 relay is also presented.
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