Synchronization of two three phase alternators, by a synchroscope method b three dark lamp method c two bright one dark lamp method 6. Also comment on the merit and demerits of the method. Electrical machines short answers instrumentation tools. Methods to determine voltage regulation synchronous impedance method mmf method zero power factor method. Regulations on 3phase salient pole alternator by slip test. The voltage regulation of all alternator is defined as the rise in voltage when full load is removed field excitation and speed remaining the same divided by the rated terminal voltage. Zs at any load value can be determined so voltage regulation of alternator at any load condition and load power factor can be calculated.
Jun 04, 2015 the voltage regulation of an alternator is defined as the rise in voltage when fullload is removed field excitation and speed remaining the same divided by the rated terminal voltage. Voltage regulation describes the ability of a system to provide near constant voltage over a wide range of load conditions. Which method gives the result nearer to the actual value. Voltage regulation of alternator by mmfampere turn method. Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on youtube. Similar to emf method oc and sc characteristics are used for the determination of regulation by mmf method. Find out regulation of alternator by emf and mmf for full load at i unity p. Mmf method of voltage regulation its phasor diagram. To calculate the voltage regulation by mmf method, the following information is required. Synchronous impedance method the synchronous impedance method or emf method is based on the concept of replacing the effect of armature reaction by an imaginary reactance. The internally generated voltage in a single phase of a synchronous machine e a is not usually the voltage appearing at its terminals.
Stator the stator or armature is an iron ring, formed of laminations of silicon steel with. Figure shows the complete phasor diagram for the mmf method. Regulation of 3phase alternator by zpf and asa methods 9. Automatic voltage regulator r610 instruction manual. The voltage regulation calculated using mmf method will always be lower than actual voltage regulation of an alternator. Voltage regulation of alternator emf and mmf methods. Why is the mmf method of estimating the voltage regulation considered as the optimistic method. Voltage regulation of alternator emf and mmf methods youtube. If which would generate a voltage e0 under no load conditions of the alternator. The mmf method replaces the effect of armature leakage reactance by an equivalent additional armature reaction mmf so that this mmf may be combined with the armature reaction mmf. Blondels two reaction theory, phasor diagram, direct axis and quadrature axis synchronous reactances, power angle characteristics, slip test. The methods employed for determination of regulation are emf or synchronous impedance method, mmf or ampere turns method and the zpf or potier triangle method.
Voltage regulation of an alternator by emf and mmf methods. Regulation of 3phase alternator by zpf and asa methods. For finding voltage regulation of an alternator, the method which gives most accurate result is a. In this experiment, the emf and mmf methods are used. Home machines voltage regulation of synchronous generator or alternator voltage regulation of synchronous generator or alternator april 21, 2020 we know that that the terminal voltage of a synchronous generator changes on application of load across its output terminals.
Mmf method is used for determining the voltage regulation of an alternator or synchronous generator is also called ampere turns. The main advantages of this method is the value of synchronous impedance z s for any load condition can be calculated. Voltage equation per phase will be similar in to the single phase alternator. Nov 22, 2015 voltage regulation of alternator and solved example. From occ the field current required to produce this normal voltage is 98 amps and is represented as i f 1 as shown in the phasor diagram.
Voltage regulation of synchronous generator or alternator. This zero power factor zpf method is used to determine the voltage regulation of synchronous generator or alternator. Mmf method of voltage regulation its phasor diagram circuit. This method of determining the regulation of an alternator is also. This mmf method is based on the results of open circuit test and short circuit test on an alternator. Requirements for calculating voltage regulation by emf method or synchronous impedance method. Regulation of three phase alternator by emf mmf and zpf page link. No load and blocked rotor test on 3phase induction motor. Voltage regulation of synchronous machine alternator by. Zero power factorzpf or potier triangle method for. In electrical engineering, particularly power engineering, voltage regulation is a measure of change in the voltage magnitude between the sending and receiving end of a component, such as a transmission or distribution line. In this method also it is assumed that the magnetic circuit is unsaturated.
Voltage regulation of an alternator by emf and mmf method. It must have an mmf which is necessary to induce the rated terminal voltage on open circuit condition. Voltage regulation of alternator by mmf method and solved problems ampere turn method regulation of synchronous generator mmf. Regulation of 3phase alternator by emf and mmf methods. Starting with zero field current, increase the field current gradually and cautiously till rated current flows in the armature. But there is one important difference between the two. Apr 20, 2016 normally for voltage regulation calculation, we use methods like. Perform no load and short circuit tests on a threephase alternator. Voltage regulation of synchronous machines alternator by. Distribution system voltage regulation and var compensation for different static load models article pdf available in international journal of electrical engineering education 374 october. This is more accurate than the emf and mmf methods.
When the load is thrown off voltage rise must be known because with the rise in voltage the insulation must be able to withstand this rise. Where ra armature resistance of alternator per phase calculate the excitation emf eo and voltage regulation for fullload and 1. Jun 11, 2015 voltage regulation of synchronous generator by mmf method. The reasons that the armature voltage e a is not equal to the output voltage v are. Voltage regulation of alternator by mmf method and solved. It equals to the output voltage v only when there is no armature current in the machine. Measure the resistance of the stator armature winding of alternator. For calculating the regulation, the synchronous method requires the following data.
C is a plot of the armature terminal voltage as a function of field current with a symmetrical three phase shortcircuit applied across the armature terminals with the machine running at rated speed. Actual load need not be connected to the alternator and hence method can be used for very high capacity alternators. Hence regulation of the alternator at any load condition and load power factor can be determined. Pdf a wide regulated series hybrid excitation alternator. When we supply the magnetizing current by dc shunt generator through two slip rings in recent alternators, they use electronic starting system instead of slip rings and commutators because the field magnets are rotating. For any synchronous generator or alternator, mmf is required, which is a. A single phase, 2000 v alternator has armature resistance and reactance of 0. Voltage regulation of alternator emf and mmf methods smile and learn. Why is the mmf method of finding alternator voltage. When operating at 60 hz, terminals 5a and 6 should be connected to each other in order to keep the low frequency protection correctly regulated. The following are the three methods which are used to predetermine the voltage regulation of smooth cylindrical type alternators synchronous impedance emf method ampereturn mmf method potier zpf method. An alternator or ac generator dynamo is a device which convert mechanical energy to electrical energy. The open circuit characteristic is the graph of the circuit.
This method is based on the separation of armature leakage reactance drop and the armature reaction effect. Synchronous impedance method armature turn or mmf method zero pf or potier method synchronous impedance method gives result which is higher than the original value. Which of the method more accurate for determine the voltage. Speed control of dc motor by armature voltage control and flux control. Which one of the following methods gives more accurate result for determination of voltage regulation of an alternator. Why is the mmf method of estimating the voltage regulation is considered as the. Blondels two reaction theory, phasor diagram, direct axis and quadrature axis synchronous reactances, power angle characteristics, slip. Explain any one of the indirect methods to determine voltage regulation. In this method both the reactance drops are replaced by their equivalent mmfs. Voltage regulation of a synchronous generator direct. May 26, 2017 the method requires following data to calculate the regulation. Explain in detail, the mmf method for predetermining the voltage.
Performance of synchronous generator connected to infinite bus, under. The regulation of a 3phase alternator may be predetermined by conducting the open circuit oc and the sort circuit sc tests. Methods to determine voltage regulation of alternator. The regulation curve is drawn between regulation and power factor viva questions. Calculating voltage regulation of a synchronous machine determines the type of automatic voltage control equipment required for resisting the voltage changes. To calculate the voltage regulation by mmf method, the following information is.
Explain in detail, the methods of determining voltage regulation of an alternator. Potier method of predetermining the voltage regulation of an alternator. A wide regulated series hybrid excitation alternator article pdf available in iet electric power applications 123 december 2017 with 73 reads how we measure reads. F regulation cp1950120 c51950121 nt1950120a0494 basic optional note. Effective resistance per phase of the 3phase winding r open circuit characteristic occ at rated speedfrequency short circuit characteristic scc at rated speedfrequency 31. Mar 28, 2015 because of the assumption of unsaturated magnetic circuit the regulation computed by this method will be less than the actual and hence this method of regulation is called optimistic method. Aug 22, 2017 the voltage regulation calculated using mmf method will always be lower than actual voltage regulation of an alternator. Using the details it is possible determine the regulation. Slip test measurement of direct and quadrature axis reactance and predetermination of regulation of salient pole synchronous machines.
The following are the three methods which are used to predetermine the voltage regulation of smooth cylindrical type alternators. They also consist of an armature winding and a magnetic field. Which of the method more accurate for determine the. Regulation of three phase alternator by emf mmf and zpf posted by. To start induction motor by rotor resistance starter 8. The voltage regulation of alternator at 100 a load at 0.
In the operation of an alternator, the armature resistance drop ir a and armature leakage reactance drop ix l are actually emf quantities while the armature reaction is basically mmf quantity. Synchronous machines notes part2 electric equipment. Normally for voltage regulation calculation, we use methods like. Because of the assumption of unsaturated magnetic circuit the regulation computed by this method will be less than the actual and hence this method of regulation is called optimistic method. Potier method of predetermining the voltage regulation of. To calculate voltage regulation of synchronous machine by m. How to draw the graph for mmf method i draw the open. The current range of the instrument should be about 2550 % more than the full load current of the alternator. The student has understood principle, construction, methods of. For any synchronous generator or alternator, mmf is required, which is a product of. Mmf method for determining voltage regulation of alternator. Electrical machines questions and answers synchronous generators voltage regulation of an alternator. Name the various methods for predetermining the voltage regulation of 3phase alternator. 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 with out change in speed and excitation.
Performance of synchronous generator connected to infinite bus, under constant power. Potier method of predetermining the voltage regulation of an. Voltage regulation of an alternator instrumentation tools. Phasor diagram, voltage regulation using synchronous impedance and potier triangle method.
Write down the equation for frequency of emf induced in an alternator. Pdf distribution system voltage regulation and var. Electrical machines ii unit i alternator basic principle a. Voltage regulation of alternator and solved example youtube. Or the numerical value of the regulation is defined as the percentage rise in voltage when full load at the specified powerfactor is switched off with speed. Voltage regulation of alternator emf and mmf methods duration. Voltage regulation of a synchronous generator the voltage regulation of a synchronous generator is the rise in voltage at the terminals when the load is reduced from full load rated value to zero, speed and field current remaining constant. Emf equation of an alternator and ac generator electrical. Name two methods used to determine voltage regulation of alternators. Mention the methods by which voltage regulation can be determined. Starting with zero field current, increase the field current gradually and cautiously till. The method is based on the results of open circuit test and short circuit test on an alternator.
480 807 306 1119 520 936 1243 1018 1519 440 1048 1107 252 612 422 820 39 44 1571 1510 1613 1321 390 182 853 17 12 1596 1128 427 545 450 581 199 245 1121 1506 1282 534 1007 823 336 1443 501