Ig is the ignition input that turns on the alternator regulator assembly. B is the alternator output wire that supplies current to the battery. Understanding the alternator four wires connect the alternator to the rest of the charging system. One pole pitch is equals to 180 electrical degrees. S is used by the regulator to monitor charging voltage at the battery. What are the methods to predetermine the voltage regulation of an alternator. When neither pole is nearest the winding, the current through the winding is zer o. The stator has salient poles with one portion of each pole. Electrical machines lab ii brcm college of engineering. A salient pole is a magnetic pole that is projected out of the rotor surface. A graphical method\ud has been developed for rapidly determining from two reactances the\ud regulation of alternators for a wide range of power factor. Two reaction model of salient pole machines, phasor.
It has 6 slots per pole per phase, conductors per slot being 4. Salient pole alternators and blondels two reaction theory. Active and reactive power control in grid connected alternators objectives. Explain the constructional details of alternator in detail. Salient pole type,the pole are projected out from the surface of the rotor and are characterized by large diameters and short axial length. Construction of a salient pole rotor is as shown in the figure at left. Analysis of salientpole synchronous generators operating. The individual field pole windings are connected in series in such a way that when the field winding is energized by the d. Power developed in salientpole synchronous generator. Because a salient pole rotor turns at low speed 50 to 300 r. It we neglect armature resistance r a and hence cu loss, then power developed p d by an alternator is equal to the power outputp out. In the cylindrical rotor synchronous machine, the air gap is uniform.
A slidingmode voltage regulator for salient pole synchronous. Consider an alternator connected to the infinite bus bar. Current starts to flow in the winding, but in the opposite direction, because of the opposite pole moving closer to the winding. Regulation of salient pole alternator using two reacti on theory objectives. Regulation of salient pole alternator voltage regulation methods e. Mcq in ac generators part 2 ree board exam pinoybix. From the fan motor in your pc to precision control of aircraft, electrical machines of all sizes, varieties, and levels of. Pdf study of salient poles synchronous generator by finite. A reduced windage loss, b reduced bearing loads and noise, c reduced noise, d adaptability of low and medium speed operation, e, leave your comments or download question paper. Methods of finding voltage regulation in synchronous generator. In non salient rotor alternators, air gap length is constant and reactance is also constant. Since rating is approximately proportional to speed, the lowspeed machines are physically large and expensive. Let v be the bus bar voltage and e be the emf induced in the alternator. As the rotor speed is lower, more number of poles are required to attain the required frequency.
Draw and explain the phasor diagram of salient pole alternator supplying full load lagging power current. The voltage regulation of an alternator for a pf of 0. The synchronous electrical generator also called alternator belongs to the family of. The cardioid diagram method of determining the voltage regulation \ud of salient pole alternators and the load voltage increase phenomenon\ud in alternators with permanent magnet excitation. Gerada is with the power electronics, machine and control group. The output voltage rating of all the alternators must be the same. Sep 24, 2020 it is because the salient pole type construction is difficult to build to withstand the stresses at high speeds.
Salient pole synchronous machine two rection theory. Aprmay 2017 mayjun 2016 the voltage regulation of an alternator is defined as the change in its terminal voltage when full load is removed, keeping field excitation and speed constant, divided by the rated terminal voltage. It is also defined as the number of slots per pole. Phasor diagram of salient pole alternator at leading power. Conduct tests to find xd and xq armature resistance if required 1. The stationary field synchronous machine has salient poles mount. To get latest updates and questions related to gate and ies like and follow our facebook page. The excitation of the alternator is adjusted in such a way that e and v are equal in magnitude. Cylindrical rotor alternators are usually long, and the problem of air f low requires very special attention.
Hydro alternators are driven by water turbines with optimum speeds in the range of 250 rpm, which requires twelve pole pairs p f n s 120. Sep 03, 2016 two reaction theory of salient pole machine it is known that in case of non salient pole type alternators the air gap is uniform. The projected poles are made up from laminations of steel. Smooth cylindrical type rotor synchronous generator mcqs. Viewdownload ppt jawaharlal nehru technological university. Smooth cylindrical type rotor synchronous generator.
Measure the line voltage and line current of the alternator. What are the various types of rotors used in the alternators. Zero power factor or potier triangle method for regulation of alternator thus the total power consists of a fundamental component and a second harmonic component which is present because the armature reaction flux has a tendency to pass through the field structure along its minimum reluctance path i. For high speed alternators or turbo alternators, which type of rotor is generally used. Ventilation or cooling of an alternator the slow speed salient pole alternators are ventilated by the fan action of the salient poles which provide circulating air. Distinguish the use of salient pole and round rotor synchronous machines.
Sep 01, 2018 in this simulation analysis, a 5 kw28 v, 24 stator slot, 4 field pole salient pole alternator were taken for analysis at a speed of 9000 rpm. In non salient pole alternators air gap length is constant and reactance is also constant. The three coils on the stator are displaced 120 and the rotor, which is a salient pole type, is supplied via the two sliprings with a d. Eeeb344 electromechanical devices chapter 5 chapter 5. High speed alternators are called as turbo alternators.
In this context, this chapter focuses on the improvements of lundell alternators that could represent the best solutions for the short term. Two reaction model of salient pole machines, phasor diagram. Draw the characteristics and determine the full load percentage regulation at a 0. In emf method, the effect of armature reaction is represented as a fictitious reactance x ar for each phase of the alternator. The advantage of salient poles in an alternator is, options are. Blondels two reaction theory, phasor diagram, direct axis and quadrature axis synchronous reactances, power angle characteristics, slip test. Salient pole alternator consists of a rotor on which projected pole are mounted on rotor as shown above. To pre determine the regulation of an alternator at full load at different power factors.
Other methods can be employed for predetermination of regulation. There are some disturbing factors in salient pole alternators which are analysed below. These alternators are driven by hydraulic turbines. Pdf this paper presents the finite elements analysis fea of a salient poles synchronous generator. Voltage regulation of an alternator is defined as the change in terminal voltage from no load to full load expressed as a percentage of rated voltage when the load at a given power factor is removed without change in speed and excitation. The stationary field synchronous machine has salient poles mounted on the. Power developed by a salient pole synchronous generator. The developed torque versus torque angle for a salient pole synchronous generator. The distance between the centres of two adjacent poles is called pole pitch. The armature reaction of an alternator influences a rotor speed. Synchronous generator converts mechanical power to ac electric power. Due to this the mmfs of armature and field act upon the same magnetic circuit all the time hence can be added vectorically. The per phase power output of the alternator is p out p d vi a coso. The salient pole alternators are slowspeed machines, speed varying from 150 to 600 rpm.
Blondels two reaction theory, phasor diagram, direct axis and quadrature axis synchronous reactances, power angle characteristics, slip. Project total field current of to the field current axis and find corresponding voltage e0 using occ. Show that the power output per phase is given by 2 9 11 sin sin2 2 v dd e v p xxx. To start induction motor by rotor resistance starter 8. Find xd and xq by the following expressions min max 3i v xd max min. The new generator rating and its performance characteristics will be investigated in our further research. Synchronization of two three phase alternators, by a synchroscope method b three dark lamp method c two bright one dark lamp method 6. Salient pole type alternators are suitable for low and medium speed alternators. The rotor winding is provided on these poles and it is supported by pole. D7escribe a method of determining direct and quadrature axis reactance of salient pole alternator.
Energise the alternator with field unexcited and driven close to synchronous speed by a prime mover. The induced torque out of a salient pole generator as a function of the torque angle. The voltage regulation of an alternator is defined as the change in terminal. The details of synchronous generators developed so far is applicable to only round rotor or non salient pole alternators.
In such machines the air gap is uniform throughout and hence the effect of mmf will be same whether it acts along the pole axis or the inter polar axis. Blondel two reaction theory salient pole alternators theory. Explain the constructional details of alternator in. A graphical method\ud has been developed for rapidly determining from two reactances the\ud regulation of alternators for a. The slow speed salient pole alternators are ventilated by the fan action of the salient. Salient pole alternator salient means sticking out or projected out. The speed of alternator at supply frequency 50 hz will maximum if it is wound for a 2 poles. As the rotor is driven by some form of prime mover, a rotating magnetic field is established and the e. Power electronic solutions to improve the performance of. Request pdf a slidingmode voltage regulator for salient pole synchronous generator this paper presents a slidingmode control strategy for voltage regulation of synchronous generators. Regulation of alternators college of engineering trivandrum. In mmf method effect of armature leakage reactance is replaced by additional armature reaction. But in salient pole alternators the length of the air gap varies and reluctance also varies. Figure 2, which shows a threephase one polepair stator with distributed winding.
As the field continues to turn, the south pole moves toward the winding as the north pole moves away. As the alternators are manufactured in large capacity direct loading of alternators is not employed for determination of regulation. Salient pole machines have more diameter and less axial length. Ee8401 important questions electrical machines 2 regulation 2017. 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. Pdf analysis of nonsalient pole synchronous generator.
The electrical machines 3 notes pdf em iii notes pdf book starts with the topics covering constructional features of round rotor and salient pole machines, suppression of harmonics, regulation by synchronous impedance method, parallel operation of synchronous generator synchronizing alternators with infinite bus bars, theory of operation. In the local circuit, the two voltages e and v are in phase opposition while in the external circuit they are in the same phase. Cross section of a salient interior permanent magnet synchronous machine. The d axis component of the armature mmf, f a is denoted by f d, and the q axis component by f q. Design of synchronous machines introduction types of. Regulation of alternators department of electrical. The component f d is either magnetizing or demagnetizing. Or the numerical value of the regulation is defined as the percentage rise in voltage when full load at the. Consider a 2 pole, salient pole rotor rotating in the anticlockwise direction within a 2 pole stator as shown in the figure below. Pdf electrical machines 3 pdf notes em iii notes 2019 sw.
In salient pole type of rotor consist of large number of projected poles salient poles mounted on a magnetic wheel. Apply 2 12 the stator of a 3phase, 24 pole alternator has 120 slots and there are 4 conductors per slot accommodated in two layers. Two reaction theory salient pole synchronous machine. Sep 30, 2019 the electrical machines 3 notes pdf em iii notes pdf book starts with the topics covering constructional features of round rotor and salient pole machines, suppression of harmonics, regulation by synchronous impedance method, parallel operation of synchronous generator synchronizing alternators with infinite bus bars, theory of operation. If the ac synchronous generator has multiple poles having, say, two, four, six. All the above methods other than direct loading are valid for non salient pole machines only. 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. Salient pole rotors have large diameter and shorter axial length they are generally used in lower speed electrical machines, say 100 rpm to 1500 rpm. Due to uniform air gap, the field flux as well as armature flux very sinusoidally in the air gap. The theory which gives the method of analysis of the disturbing effects caused by salient pole construction is called two reaction theory. It has a large number of projecting salient poles, having their cores bolted or dovetailed onto a heavy magnetic wheel of castiron, or steel of good magnetic quality fig. The pole structure of the rotor of a salient pole machine makes the air gap highly nonuniform. The component f q results in a crossmagnetizing effect.
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