A phasor diagram is a representation of sinusoidal waves in circular format. Synchronous machines the inductance of the stator winding depends on the rotor position energy is stored in the inductance as the rotor moves, there is a change in the energy stored either energy is extracted from the magnetic field and becomes mechanical energy that is, its is a motor or energy is stored in the magnetic field and. Construction and principle of operation of synchronous generator. The synchronous reluctance machine is considered as a balanced three phase circuit, it is sufficient to draw the phasor diagram. Before we draw phasor diagram, let us write the various notations for each quantity at one place. Synchronous and asynchronous electricmotors the electric motor is an electromechanical continuous energy conversion equipment that converts electrical energy into electrical energy mechanical energy. Permanent magnet synchronous machines have been applied to servo drives for a long time already, and nowadays, there are quite large permanent magnet synchronous machines also in. Derive the power developed by the synchronous motor. Similarly, motor armature current ia has two components. Synchronous motors introduction it may be recalled that a d. The permanentmagnet synchronous machine pmsm drive is one of best choices for a full range of motion control. A synchronous condenser when connected to supply mains takes leading current and hence delivers the.
Synchronous motor control electrical part manual s. Equivalent circuit and phasor diagram of a synchronous motor. I will suggest you to download the ppt or pdf file which covers step by step phasor diagram of transformer for no load, lagging load and leading load condition. Split phase induction motor operation and characteristics. When the motor reaches about 75% of synchronous speed, the centrifugal switch opens the circuit of the starting winding. A synchronous motor is not selfstarting and an auxiliary means has to be used for starting it. The short film ac motors 1969 is available for free download at the internet archive. Weg synchronous motorsindustrialapplicationsusa10058brochureenglish. Synchronous motors,principle of operation,methods of starting synchronous motor,behaviour of a synchronous motor,equivalent circuit model and phasor diagram of a synchronous motor.
A synchronous electric motor is an ac motor in which, at steady state, the rotation of the shaft is synchronized with the frequency of the supply current. Other members of the family are the directcurrent dc motor or generator, the induction motor or generator, and a number of derivatives of all these three. The speed of a synchronous motor with constant rotor excitation is determined by the stator frequency and the number of poles. Pdf investigate the performance characteristics of three. Unit i synchronous generator ee8401 syllabus electrical machines 2. How to know whether it is leading or lagging in power. Single phase induction motors sizes vary from 1400 kw to 125 kw are used in toys, hair dryers, vending machines etc. Synchronous motor is used as synchronous condenser for power factor correction or improvement. Therefore, a synchronous motor can be made to carry the mechanical load at constant speed and at the same time improve the power factor of the system. 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. Synchronous motor phasor diagram instrumentation tools. The resistor current and ohmic values are determined by the motor designer.
Synchronous reluctance machine design 1 1 introduction the purpose of this report is to present information necessary for developing a suitable synchronous reluctance motor synrm rotor geometry design procedure. Equivalent circuit and phasor diagram of non salient synchronous machine. Complete electrical machines for electrical engineering. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. In order to draw the phasor diagram, vt is taken as the reference phasor and below points are to be followed.
Synchronous and asynchronous electromechanicalsystems dr. As shown in the typical starting curve, these motors will start and. The phasor diagram of a salientpole synchronous generator. A synchronous machine is an ac rotating machine whose speed under. Mar 10, 2015 therefore, a synchronous motor can be made to carry the mechanical load at constant speed and at the same time improve the power factor of the system. Syn mc phasor diagram part 1 free download as powerpoint presentation. Synchronous reluctance motor the name synchronous reluctance motor indicates, must rotate at synchronous speed. Ee 340 spring 2011 university of nevada, las vegas. A explain in detail about power circles of synchronous motor. As the name implies, a synchronous motor runs at synchronous speed n s 120fp i. The attached pdf contains all questions asked in previous years of electrical engineering gate exam for the topic electrical.
A short course on synchronous machines and synchronous. We will discuss here the simplest way of drawing the phasor diagram for synchronous motor and we will also discuss advantages of drawing the phasor diagram. Thus, a simplified phasor diagram indicates that sin cos a a s e i x 27. The normal speed of the motor is below the synchronous speed and depends upon the load on the motor. Power and torque in synchronous generators then the real output power of the synchronous generator can be approximated as 3 sina out s v e p x we observe that electrical losses are assumed to be zero since the resistance is neglected. The synchronous reluctance motor is completely free of magnets and their operational problems. Electrical machines 2 syllabus ee8401 pdf free download. If a machine works as a asynchronous motor then the direction of armature current will be opposite to that of the excitation emf. Phasor diagram of a synchronous generator similar concept as applied in chapter 2 transformers. Synchronous condenser is an overexcited synchronous motor without having any mechanical load connected to its shaft. Pdf principles of electrical machines book by vk mehta. True synchronous motors are driven by sine waveforms. And from milestone three to five we understand the steady state behaviour of synchronous motor under. Phasor diagram for synchronous motor electrical study.
The phasor is made of a vector with magnitude proportional to the magnitude of e, rotating at a constant rotational speed. Pdf ee6504 electrical machinesii emii books, lecture. Phasor excitation emf always lags phasor terminal voltage. It is a serious competitor to the induction machine in variable speed applications. The complete phasor diagram of a salientpole synchronous motor, for a lagging power factor. There are four elements in the equivalent circuit of a synchronous generator. In this chapter, we shall focus our attention on the construction, working and. Of synchronous machines the synchronous electrical generator also called alternator belongs to the family of electric rotating machines. As long as an efficient, variable frequency power supply was not available this meant constant speed operation at fixed frequency. Only install this equipment in zones known to be free of. The phasor diagram for the synchronous motor is given below, in the phasor one the direction of the armature current is opposite in.
What is armature reaction and how it is produced in synchronous machine armature reaction for unity power factor, lagging power factor and leading power factor with the help of phasor diagram. Synchronous motor working principle instrumentation tools. The final expression for the phase voltage of a salientpole synchronous generator is as mentioned in eq. Jun 04, 2015 equivalent circuit of a synchronous motor. As a synchronous motor has no selfstarting torque, then. In either case, it is classified as a permanent magnet inductor motor. To achieve this a suitable theoretical model is essential, thus a simple but complete motor model is developed. Synchronous motor phasor diagram equation 2 is the preferred form since the terminal voltage is normally chosen as the reference phasor for purposes of drawing a phasor diagram. An ac motor is an electric motor driven by an alternating current ac. 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. Unlike ac induction motors which always run at a lagging power factor, syn. Ppt chapter 6 synchronous motors powerpoint presentation.
Permanent magnet synchronous machines as brushless. O synchronous reactance per phase 4 armature resistance per phase. Starting and pullin torques are designed to accommodate electrical system. Hi electrical engineering gate aspirants, i am sharing the electrical machines solved previous year questions for gate. When two unlike poles are brought near each other, if the.
Equivalent circuit and phasor diagram of salient synchronous machine. Power circles of synchronous motor pdf please purchase pdf splitmerge on. For a given phase voltage and armature current, a larger internal voltage ea. With a known terminal voltage, we can construct phasor diagrams for the synchronous motor, as shown in figure 2. Figure 1 displays the block diagram of the control system.
The synchronous machine synchronous ac machines find application as motors in constant speed applications and, when interfaced to the power source with a variablefrequency converter system, in variablespeed applications. A vector plot of voltages and currents within one phase is called a phasor diagram. Another way of saying this is that it has zero slip under usual operating conditions. Permanentmagnet synchronous machine drives intechopen. Explain the constructional details of alternator in detail with neat sketches. In this chapter, we shall focus our attention on the construction, working and characteristics of commonly used singlephase motors. V terminal voltage r e effective resistance x l leakage reactance x a fictious reactance x s synchronous reactance e counter emf. Synchronous motors are generally of the salient pole type. In a phasor diagram the vector is repeated per angle in anticlockwise direction.
Wegtheabcs of synchronous motorsusaem200syn42brochureenglish. The resultant flux is no longer on the direct axis, and. Download link is provided and students can download the anna university ee8401 electrical machines ii emii syllabus question bank lecture notes part a 2 marks with answers part b marks and part c 15 marks question bank with answer, all the materials are listed below for the students to make use of it and score good maximum marks with our study materials. Equivalent circuit model and phasor diagram of a synchronous motor the equivalentcircuit model for one armature phase of a cylindrical rotor three phase synchronous motor is shown in fig. Synchronous motors can operate at leading power factors, providing vars to the power system, reducing demand charges often caused by induction motors. In stator winding two effects are to be considered the effect of field cutting stator conductors at synchronous speed and the effect of stator revolving field. Adjust the field excitation of the synchronous machine so that about rated voltage 400v, ll is obtained. Large synchronous and induction motors part i general information shipment and handling before shipment, all motors are assembled, inspected and tested to eliminate electrical and mechanical defects. Synchronous motor applications electrical concepts. To find oul, examine a synchronous motor operating initially with a leading power factor, as shown in figure 66. The brushless woundrotor doubly fed synchronous motor system has an independently excited. In like manner, an alternator may operate as a motor by connecting its armature winding to a 3phase supply.
Ee8401 syllabus electrical machines 2 regulation 2017 anna. Highperformance variablespeed motor drives are often constructed using a permanentmagnet synchronous motor. Construction and principles of operation the slosyn motor is unique in that it has the capability of being operated as an ac synchronous, constant speed motor or as a phase switched dc stepper motor. Succinctly divided in 14 chapters, the book delves into important concepts of the subject which include armature reaction and commutation. If the load on the shaft of the motor is in creased, the rotor wi ll initially. Armature reaction phasor diagrams of non salient pole synchronous generator connected to infinite bussynchronizing and parallel operation synchronizing torque change of excitation and mechanical input. The phasor diagram when the motor is on load is shown in fig.
While the voltages are constant, the induced torque of the synchronous motor only depends. Pdf efficiency analysis of synchronous reluctance motors. The phasor diagrams for a b lagging pf, c unity pf, and d leading pf. Power factor correction with synchronous condenser for power.
An important advantage of a synchronous motor is that the motor power factor can be controlled by adjusting the excitation of the rotating dc field. In case of synchronous motor revolving field structure is to be energized by direct current. Commons attribution cc by license, which allows users to download, copy and. Phasor diagram of a synchronous generator similar to that of a transformer since the voltages in a synchronous generator are ac voltages, they are usually expressed as phasors. Constant speed synchronous motor speed is unaffected by line or load conditions, providing greater operating flexibility. Phasor diagram of under excited synchronous motor the phasor diagram shown in fig.
Two or threephase drive may be used by supplying the appropriate number of windings in the stator. The synchronous reluctance machine is considered as a balanced three phase circuit, it is sufficient to draw the phasor diagram for only one phase. Though these machines are useful for small outputs, they are not used for large powers as. Variable frequency synchronous motor drives springerlink. Phasor diagram per phase of synchronous pm machine. Pdf electrical machines gate solved questions previous. Power factor correction by synchronous motors instrumentation.
The steadystate speed is constant from noload to fullload. Eeeb344 electromechanical devices chapter 5 chapter 5. A motor is an electromechanical device which converts electrical energy to mechanical energy. A short course on synchronous machines and synchronous condensers. The block diagram shows the drive electronics associated with a low voltage 12 v dc synchronous motor. Electrical machines questions and answers synchronous motors synchronous motor phasor diagram. May 15, 2018 x s synchronous reactance e counter emf. When w and wm are converted into cycles per second or hz and revolutions per minute respectively, we have. Explain the constructional details of alternator in. Synchronous motor copyright 2004 kilowatt classroom, llc.
You can download these technical publications and other technical information from. Save my name, email, and website in this browser for the next time i comment. Voltage for a superior motor synchronous motor characteristics starting and stopping rapid starting, stopping and reversing are among the advantages of superior electric synchronous motors. Types, construction and principle of operation, 3 phase induction motor, general phasor diagram, equivalent circuit, power and torque relations. Synchronous machines 6 where w is the angular frequency of emf in electrical radians per second and wm the angular speed of the rotor in mechanical radians per second. For example if you take two sinusoids denoting current and voltage and plot their phasor. The steadystate performance characteristics of the synchronous motor may be studied using the equivalent circuit shown in fig. Download link is provided and students can download the anna university ee6504 electrical machinesii em ii syllabus question bank lecture notes syllabus part a 2 marks with answers part b 16 marks question bank with answer, all the materials are listed below for the students to make use of it and score good maximum marks with our study materials. The dp damper winding protection relay protects the damper winding of the synchronous motor. A phasor diagram of a synchronous generator with a unity power factor resistive load.
On speed control of a permanent magnet synchronous motor with current. A synchronous electric motor is an ac motor distinguished by a rotor spinning with coils passing magnets at the same rate as the alternating current and resulting magnetic field which drives it. Synchronous motor mainly runs on principle of magnetic locking between rotor and rmfrotating magnetic field. The motor then operates as a singlephase induction motor and continues to accelerate until it reaches the normal speed. May 15, 2018 we will discuss here the simplest way of drawing the phasor diagram for synchronous motor and we will also discuss advantages of drawing the phasor diagram. The motors will start within 112 cycles of the applied frequency and will stop within 5. Above two points are sufficient for drawing the phasor diagram for synchronous motor.
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