Difference Between AC and DC Motors; Difference Between AC and DC Generator; Synchronous Motor. An induction generator or asynchronous generator is a type of alternating current (AC) electrical generator that uses the principles of induction motors to produce electric power. If the conductor is part of a closed circuit, this force will move electrons and current will flow. Thank you so much, Mohammed Imran. When an Induction Motor is connected to 3-phase power, the magnetic field starts to rotate instantaneously. There are various types of motors available as classified below. It has unity or lagging or leading power factor. Different structure settings. Types: DC motor and AC motor. More about Induction Motors. Using Damper Winding as a Slip Ring Induction Motor (Synchronous InductionMotor). Figure 11: Differences between a 3-pole and a 6-pole stator winding. - Speed of synchronous motor is constant at all load. The direction of the magnetic field always goes from North to South, so referring to the magnetic flux lines outside the loop, we can draw in the N & S poles. Test your knowledge and practice online quiz for FREE! An induction motor operates only at a lagging power factor. Principle. When induction generators are used in larger wind turbines, they are designed as three-phase ac machines. Direct Current (DC) Excited Synchronous Motors. What if we used the same wire and wrap it around 4 poles instead? Different types of motors are used in industries and homes according to . Right picture: Both N points to an X and both S to a . Types of circuit breaker. Normally, for a solenoid (coil) one end is N and the other S with 180 between them. An induction generator is frequently used in hydel power plants, wind energy production, and they have the ability to cut the higher-pressure air to less pressure since they have the aptitude to reestablish power with the coolest way. It is self-starting the motor. The fields direction always points from North to South. Its armature winding is energized from an AC source and its field winding from a DC source. - Synchronous motor rotate because of magnetic locking between rotor poles and stator poles. Yet the change of magnetic field (synchronous speed) would still be 50 times/s. How to make the single-phase Induction motor self-starting? Dont forget, this is one wire. Synchronous motor. Initially the motor is wired in a star configuration, where the phase voltage is smaller than the line voltage, next, when the motor is running it is switched to a Delta config. Advantages: An asynchronous generator is an AC . In a generator, current is produced in the armature winding. Why? Difference Between Induction Motor And Synchronous Motor. We define the North and the South poles based on the magnetic fields direction outside the cage. In AC supply, single-phase and three-phase motors are available. It is the stationary part of the Induction Motor which consists of a series of wire windings, The stator is made up of a steel frame which supports a hollow cylindrical core, The core consists of stacked laminations that have evenly spaced slots where the stator winding is placed. The Induction Motor becomes a generator when it is connected to an electrical power system and then driven above its synchronous speed by some prime mover. Lets take the example that we have in the picture. The difference between the excitation of the induction motor and the synchronous motor is that the induction motor is a singly excited machine. Application: Used in pumps, compressors, paper mills, textile mills, lathes, Drilling machines industrial drives. So let get started Difference between Induction Motor and Induction Generator, That is all about the Difference between Induction Motor and Induction Generator. Also, here is a good video that explains more about a Star & Delta starter. Lorentz Force Right Hand Rule. This is great for size-constrained applications and is a reason to choose a synchronous motor over an induction motor. We already have a great tool for this: the squirrel cage! Which is more efficient induction motor or synchronous motor? The induction generator always rotates at more than synchronous speed (Nr>Ns). Figure 11: Differences between a 3-pole and a 6-pole stator winding. Synchronous Motor vs Induction Motor - Difference Between Induction Motor and Synchronous Motor.#Induction_Motor #Synchronous_Motor #Learning_Engineering#kon. In a generator, on the other hand, the armature or windings of wire spin inside a fixed magnetic field to generate electricity. The fields direction always points from North to South. Difference between a 2-pole rotor ,3-pole stator machine and a 4-pole rotor, 6-pole stator machine. Connected Supply. Designed and Developed by, Difference between Induction motor and Synchronous motor. It can be constructed with wider air gaps than induction motors which makes it better mechanically. It is a non-self starting motor. The 2-pole DC electromagnet in the diagram has a fixed N and S poles and they lock with the rotating N & S poles of the 3-phase magnetic field. An induction motor is used for driving mechanical loads only. (50 cycles per second). Hold a wire in your hand. The synchronous electric motor which works on AC current is used in domestic grinder, the motor is winding is done with copper wire to produce a magnetic effect to the rotor, the rotor, in turn, revolves with a high speed as per the capacity and power utilized by them. The synchronous motor working principle is magnetic locking, when two, unlike poles, are brought near each other, if the magnets are strong, there exists a tremendous force of attraction between those two poles, in that case, the two magnets are said to be magnetically locked. An induction motor is cheaper than the synchronous motor of the same output and voltage rating. The direction of the magnetic field always goes from North to South, so referring to the magnetic flux lines outside the loop, we can draw in the N & S poles. Higher Efficiency especially in low-speed unity power factor. When Three-phase voltages are applied to electric conductors which are placed in a certain geometrical position which are specially arranged (At certain angles from one another), a rotating magnetic field produces. Portable, inverter, and standby: Working principle In a synchronous electric motor, the rotation of the shaft is synchronized with the frequency of the supply current. Use the Right Hand Rule to see the magnetic field. It always runs at synchronous speed. 4. A single-phase induction motor is used for the mixers and grinders. Synchronous motor: Stator poles rotate at the synchronous speed (Ns) when fed with a three phase supply.The rotor is fed with a DC supply. When we have the same type of pole at the opposite side, the two sides are wired out of phase. Induction motor runs at the non-synchronous speed. Difference in Applications. Synchronous Motor Is A Doubly Excited Machine, Whose Armature Winding Is Energised From AC Source And Its Field Winding Is Energised From DC Source. Synchronous machine are similar to Induction machines. Because initially the cage is static and all a particular bar sees is a constantly changing North & South poles (from the rotor). An induction or asynchronous generator is an electric induction motor driven at speeds above its synchronous speed. Note, it is heading in a different direction inside the cage than outside (blue arrows). It is so called because it never runs at synchronous speed. 7. It is a handy tool to determine the direction of the current in a particular bar at a given point. The electromagnetic motor which converts electrical energy into mechanical work at variable speed is called as a Induction Motor. This is called Lorentz Force. Consider a two-pole simple rotor (shown in the above figure). Application: 1. The rotating magnetic field induces a current flow in the squirrel cage bars based on the law of electromagnetic induction. @2020 - automationforum.co. It can be operated under a wide range of power factors both lagging and leading. It runs at less than 1500 rpm. This sounds easy, but when the motor is initially started, the magnetic field changes very fast around the DC electro-magnet, so it attracts and next repels. Key Differences Between Motor and Generator. It is self-starting the motor. What is the application of 3-Phase Induction Motors? A cross-section of the Induction motor is shown below, An Induction Motor basically consists of two parts. It means that only a single source . V Curve of a Synchronous Motor. The difference between them begins with the way the magnetic field of the rotor interacts with the stator. An induction generator produces . The synchronous motor has more power efficiency due to the unity or leading power factor. Hold out your hand. Induction generator is a motor that uses electromagnetic induction between the rotors to induce current in the rotor to achieve electromechanical energy conversion. In the case of a 4-pole setup, the rotor only has to turns 25 times to generate the same 50Hz. Thanks for reading have a good day. The colours indicate each phase, The. These are AC motor (Synchronous & Induction motor) and DC motor (Series, shunt & compound motor). The rotating magnetic field induces a current flow in the squirrel cage bars based on the law of electromagnetic induction. s is the slip, Ns is the magnetic field speed, n is the rotor speed. Current comes in via the 3 phases and since it is alternating current it creates a rotating magnetic field in the stator. There are so called slip rings attached to the pole. Speed of Synchronous motor is independent of the load and always runs at synchronous speed. This works the same principle as in induction motors. Many times you will be asked to compare these two types of motors. Since, the field is excited by the power system, the synchronous generator can deliver only real/true power but absorbs the reactive power. Thumb shows the direction of the current and the fingers indicate the direction of the magnetic field. Thus, we can draw the N & S poles. But the induced current itself in each bar will have its own magnetic field that will repel the stators field, thus, creating a force. The dc generators also work on the same principle. This is why induction motors are also known as asynchronous motors. Squirrel Cage (part of the rotor) in an Induction Motor. Can induction motor produce electricity? Normally, for a solenoid (coil) one end is N and the other S with 180 between them. Synchronous generators are controllable by governors which monitor system frequency and adjust prime mover input to bring correction to frequency . As Mr. Bhupendra Desia rightly explained about the differences.Induction generator produces electricity by having the difference in the rotor speed (Nr) and the synchronous speed (Ns) is that for . Alternating Current is fed into the winding. The rotating field in the static share of the motor will cause flux alteration in the rotor which reasons it to move, with a speed fewer than the synchronous speed. Different types of motors are used in industries and homes according to their construction and use and features. The magnetic field of the rotor is supplied by direct current or permanent magnets. If we add back the other two conductors, each being. This motoris cheaper than the synchronous motor. We cant have the two N poles send the electrons against each other. In the supply system of the induction motor, stator winding is linked by an AC source. The idea behind electricity generation is that a form of rotational (kinetic) energy is converted into electricity. This is because both magnetic fields point at the same direction and will repel each other. In the reluctance motor, the rotor has projecting poles that resemble individual teeth. The Lorentz Force will be symbolised by an arrow that come out from your palm. Rao Kattoju, Thank you very much, Veerabhadra for your kind words. 2. This is a resource page from Physclips, a multi-level multimedia introduction to physics ( download the animations on this page ). difference between slip rings and commutator. This is happening in all 3 phases. The motor then turns at synchronous speed so long as the required torque is low. What is Induction Motor (or) Asynchronous motor? Relative motion is required between stator and rotor, Relative motion is not required between stator and rotor, The induction motor always runs below the synchronous speed Ns=120f/p. On the right, we have a 4-pole rotor with a 6-pole stator. The major difference between Motor and Generator is that a motor converts electrical energy into mechanical energy, whereas the generator does the exact opposite. What are slip and slip speed in an induction motor? Synchronous motors are having better efficiency, than induction motors. As load increases, load angle increases keeping speed constant at synchronous, The induction motor is a single exciting machine, Synchronous motor is Double exciting machine, Speed control is possible through difficult. Essentially, we have a coil that is wrapped around the rotor. A synchronous motor/generator has a rotor with either a permanent magnet or an electromagnet energized through slip rings from an external DC source. While Generators is a device that are used to convert mechanical energy into electrical energy. Answer (1 of 9): The same as the differences between a synchronous motor and an induction motor, because they're the same things. Specific Gravity of Cement. Construction of a 3-phase induction motor. So, both synchronous and induction machines can be used as generators or motors. The rotating magnetic field produced in the stator will create flux in the rotor, hence causing the rotor to rotate. Non-Excited Synchronous Motors are available in three designs: Example: Crushers, Rolling Mills, Steel Mills, Metal rolling mills, Pulps, Grinders. Very easy to understand the way you compare both motors. Lets study the comparison between both AC motors in tabular form. What is Circuit breaker? The rotor will rotate only at one speed in the synchronous generator unlike the induction motors. Fan, blowing fan, a dryer is an example of the synchronous motor. These two AC motors are-. What we have is a coil. The fundamental difference between these two motors is that the speed of the rotor relative to the speed of the stator is equal for synchronous motors, while the rotor speed in induction motors is less than its synchronous speed. For example water moves the turbine and it makes the prime mover spin. Zero slip (S=0) occurs in the synchronous motor. Electric motors and generators. A synchronous motor is costlier than an induction motor of the same output and voltage rating. A Synchronous motor is a double exciting machine i.e., two electrical inputs are provided to it. Since it is hard to lock for the DC electromagnet onto the fast spinning stator field, a squirrel cage is used to give an initial rotation for the rotor. On the other side, in a synchronous motor, the armature winding is energized by an AC source while a DC source energizes the field winding. The first electric motor was a simple electrostatic device by Scottish monk Andrew grandson and benjamin franklin in the 1740s. difference between slip rings and commutatorrose center for earth and space | difference between slip rings and commutatorrose center for earth and space | difference between slip rings and commutator Current comes in via the 3 phases and since it is alternating current it creates a rotating magnetic field in the stator. Here is a good YouTube video that visualise Lorentz Force in action. Thesquirrel cage induction motorsare used in residential as well as industrial applications especially where the speed control of motors is not needed such as: Theslip ring motorsare used in heavy load applications where the high initial torque is needed such as: Synchronous motor rotor generally rotates at a constant speed as the revolving field in the machine. A synchronous motor can run . In a 4 pole scenario the N and S poles change every 90. As we know rotating magnetic field rotates with synchronous speed when two opposite poles of the rotor and RMF locked rotor also rotates with the same speed of RMF in the direction of the rotating magnetic field. Their purpose is to change rotational energy to electrical energy and vice-versa. Based on the source nature, the electric motor is of two types. If the conductor is part of a closed circuit, this force will move electrons and current will flow. The motor is costly and requires frequent maintenance. It starts up from rest and needs no extra starting motor and has not to be synchronized, its starting arrangement is simple in squirrel cage type motor. This makes the currents flow in different directions. As the N & S poles rotate, so will the current change direction in each bar. Hope this will help you for the preparation of the exam or interview. Synchronous Machine. The efficiency depends on the specific motor type and size, but the lack of slip in synchronous . Sure, I will add the construction point in the comparison of both machines. Intuitively, it makes sense that as more power is required by the mechanical load on the motor, one or both of the magnetic fields must get stronger. Excellent. All Right Reserved. DC Field. Difference Between Synchronous and Asynchronous Motor, Difference Between Slip Ring & Squirrel Cage Induction Motor, Two Wattmeter Method of Power Measurement, Difference Between Semiconductors and Superconductors, Difference Between Shunt and Series Voltage Regulator, Difference Between Symmetric and Asymmetric Multiprocessing. It is always less than the synchronous speed. It is not self starting. Induction motor has self starting torque. Why Induction motors are called Asynchronous motors? for the rotor rotating). Due to the usage of the occurrences of the electromagnetic induction (this phenomenon be contingent on Faradays law), there is no electrical joining amongst the rotor circuitry and stator of the motor comparable the transformer. The second key part induction motor is the rotor, it is the revolving share of the induction motor. This cage is next placed inside the stator. Although, in real life it looks more like in Figure 6. Similarly, it also consists of two main parts- the stator and rotor. Synchronous motors are generally more efficient than induction motors. 5. If done so, the rotor poles get magnetically coupled with the rotating stator poles, and thus the rotor starts rotating at the synchronous speed. Dont forget, the magnetic field goes in a loop, but we consider the arrows that are outside the pole. The motor cant use in such applications where high starting torque is necessary. The fundamental difference between these two motors is that the speed of the rotor relative to the speed of the stator is equal for synchronous motors, while the rotor speed in induction motors is less than its synchronous speed. This is a DC electromagnet. This is called slip. 3. Thanks, Mathew Varghese. Additional damper winding is necessary. ; It has a solid armature, or squirrel cage, that is an electrical short circuit.When the current is connected, the machine will start turning like a motor at a speed that is just slightly below the synchronous speed of the rotating magnetic field from the stator. By contrast, the induction motor requires slip: the rotor must rotate slightly slower than the AC alternations in order to induce current in the . An induction generator produces electrical power when its rotor is turned faster than the synchronous speed. So, now we have an alternating current in the squirrel cage bars. But hey, once the rotor slows down, the magnetic field seems to rotate again and we start the whole process from the beginning. The asynchronous nature of induction-motor operation comes from the slip between the rotational speed of the stator field and somewhat slower speed of the rotor. Electrons, as they move in a wire, create a magnetic field. According to its working principle, it is also called "induction generator". This force will make the cage rotate. It works on the principle ofmagnetic locking. Thanks for the Excellent explanation. AC machines are based on the principle of electromagnetic induction. . Alternating Current is fed into the winding. An induction motor is cheaper than the synchronous motor of the same output and voltage rating. Some are dc motors and some as ac motors and generators and perform different functions. I am a professional engineer and graduate from a reputed engineering university also have experience of working as an engineer in different famous industries. Only an AC source is required to operate, it doesnt require DC excitation. The same four-pole motor operating on a 50 Hz grid will have a . If you are doing preparation for the exam, viva, or interview, you will be asked questions- synchronous vs induction motors. What are the differences between the Induction motor and the Synchronous motor? These were the main motor and generator differences that can be asked in the exams. The induction motor is mostly used in industrial applications. The brushes only touch the rings. Motoris a device that used to transform electrical energy into mechanical energy. The magnetic field always points, In the above diagram, the North and South poles will change positions 50 times a second. In a synchronous generator, the waveform of generated voltage is synchronized with (directly corresponds to) the rotor speed. No DC field current is required. This means for example the North pole of the electromagnet will attract the South pole of the rotating magnetic field. 12) Speed, in RPM (revolutions per minute). Figure 5: Flemings Right Hand Rule. Thanks! We can even have more poles. Power factor is lagging in induction motor and unity in synchronous motor. What is the application of Synchronous Motors? Its stator winding which consists of a 3-phase winding is provided with a 3 phase supply and the rotor is provided with a DC supply. Although, when there is a current in a wire (or bar in our case), the current will induce a magnetic field itself. Mostly used in Single phase Induction motor. An induction motor is a singly excited machine, that is, its stator winding is energized from an AC source. For Induction motor, relative motion is required in between the stator and rotor. Your. This field induces a current in the bars. These are connected to an external power source via brushes. MV = High Efficiency +1~2%. As the current alternates, so does the direction of the magnetic field and poles. S - slip, Ns - the magnetic field speed, N - the rotor speed. Synchronous Speed / Advantages. 3. The ends of windings are brought out at both ends and connected to the slip rings, The rheostats are connected between the slip rings and the winding ends. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); @ 2022 DipsLab.com. i.e., Ns = 120f/P. The induction motor is less efficient than the synchronous motor. They operate at a more simplistic principle and theyre also cheaper to manufacture. When they approach synchronous speed, the slots enable the synchronous magnetic field to lock onto the rotor. In a motor, current is supplied to the armature winding. An Induction Motor is an AC electric motor in which the electric current in the rotor is produced by electromagnetic induction from the magnetic field of the stator winding. The main difference between them is in regard to what spins and what is fixed. The Synchronous Motor can be used for power factor correction in addition to the supplying torque to drive mechanical loads whereas an induction motor is used for driving mechanical loads only. Now, if the squirrel cage (rotor) starts to rotate, eventually it catches up with the synchronous speed (rotors magnetic field). The stator carries a 3-phase winding while the rotor . An AC generator that has working occurrences alike to the. The magnet needs power. It is the speed of the rotating magnetic field in the stator part of the induction motor. This leads to the rotor to slow down. For a typical four-pole motor where there are two pairs of poles on a stator operating on a 60 Hz electrical grid, the synchronous speed is 1800 rotations per minute. This article presents top 10 differences between induction and synchronous motors. 2) Reference to this standard, that is, Indian standard/European standard. The induction motor always runs at speed less than its synchronous speed. These are very important topics in electrical engineering. Real power is being supplied by prime mover input and reactive power is absorbed from the system. Advantages of Synchronous motors. So, in the case of synchronous motors, instead of generating a Lorentz Force, we lock the poles of the stators DC electro-magnet with the rotating 3-phases field. If the load increased the speed of the induction motor decreases. The speed is always less than synchronous irrespective of the load. Thus, we can draw the N & S poles. It works on the principle ofelectromagnetic induction. Induction generator has the advantages of simple structure, firmness, small size, light weight, less auxiliary equipment, convenient operation and maintenance, etc. the motor/generator acts as a motor. Based on the number of rotor poles we can distinguish between: 4-pole rotor of a 3-phase synchronous generator. Very simple and almost unbreakable construction in squirrel cage type. Use the Right Hand Rule to see the magnetic field. Which is better induction motor or synchronous motor? We came up with the basic definitions of what are induction and synchronous generators . To know more about the Star & Delta config, check out this earlier post. This happens so fast that what we witness in real life, is that the machine rotates a bit slower than the synchronous speed. Fundamentals: (1) When a three-phase asynchronous motor is connected to a three-phase AC power supply, a three-phase magnetomotive force (stator rotational magnetomotive force) generated by a three-phase stator . Here, Im comparing synchronous motor and asynchronous motorwith their specifications, functions, applications, and examples. The speed is always less than synchronous but never synchronous. Working Principle of Synchronous generator : The alternators work on the principle of electromagnetic induction. The synchronous motor is made self-starting byproviding a special winding on the rotor poles, known as damper winding or squirrel-cage winding. The power factor is very low during light load conditions. The rotor of a synchronous motor behaves like permanent magnetic or electromagnetic and its field interacts with . ISO 9001:2015 (Quality Management System), ISO 14001:2015 (Environmental Management System), ISO 45001 : 2018, OEKO-TEX Standard 100 The electricity is supplied from brushes to the slip rings. This conductor is rolled up in a coil. means it is going in the page, whereas the dot means coming out. (mechanical for motor, electrical for alternator) Now, the difference between a synchronous machine and an induction machine is based on how the rotational magnetic field is utilized.