At high loads, the power factor of the induction motor becomes very poor. A three phase induction motor is a device in which the rotor rotates at speed slightly less than the synchronous speed. While Generators is a device that are used to convert mechanical energy into electrical energy. 1. It is also is recognized as the. Synchronous motor runs at the synchronous speed. AC motor is further divided into 2 types -synchronous motor and induction motor. Synchronous motors are having better efficiency, than induction motors. The motor will operate in DC and AC power supply. 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. In case of a simple synchronous generator, the rotation of the prime mover is in synch with the synchronous speed (magnetic field). We will see why in a bit. If the conductor is part of a closed circuit, this force will move electrons and current will flow. The construction of the induction motor is relatively easy. A Synchronous Motor operated backwards work as a generator. The second key part induction motor is the rotor, it is the revolving share of the induction motor. Real power is being supplied by prime mover input and reactive power is absorbed from the system. The cage has a rotating field around (which is from the 3-phase windings in the stator). What is a soft starter? 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. It is very simple. When induction generators are used in larger wind turbines, they are designed as three-phase ac machines. The motor is cheap, especially cage rotors and maintenance-free. Construction of a 3-phase induction motor. Induction motor. 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 difference between them begins with the way the magnetic field of the rotor interacts with the stator. Practically it is not possible for stator poles to pull the rotor poles from their stationary position into magnetic locking conditions. What is Induction Motor (or) Asynchronous motor? The magnet needs power. If the load increased the speed of the induction motor decreases. Construction of a Synchronous Motor. Thanks for reading have a good day. The turn is also in the opposite direction. Electrons, as they move in a wire, create a magnetic field. Difference Between AC and DC Motors; Difference Between AC and DC Generator; Synchronous Motor. As the N & S poles rotate, so will the current change direction in each bar. A three phase induction motor is a device in which the rotor rotates at speed slightly less than the synchronous speed. 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. Hold a wire in your hand. The synchronous motor is made self-starting byproviding a special winding on the rotor poles, known as damper winding or squirrel-cage winding. Left picture: N points to an X, S points to a . The image shows the two states of the current and how it changes the magnetic poles accordingly. Your email address will not be published. Can induction motor produce electricity? Specific Gravity of Cement. What are the Indications of winding faults in an Induction Motor? We already know that in the stator there is a rotating magnetic field. Induction generator has the advantages of simple structure, firmness, small size, light weight, less auxiliary equipment, convenient operation and maintenance, etc. The electricity is supplied from brushes to the slip rings. Hold a wire in your hand. A synchronous motor is costlier than an induction motor of the same output and voltage rating. Induction generators use an armature to create an electric field that causes Starter motors to run. This generator workings in a motorized way as the speed of revolution of the generator is upper than the synchronous speed. Your other four fingers will indicate the direction of the magnetic field. A synchronous motor can be operated with lagging and leading power by changing its excitation. This makes the currents flow in different directions. Breakdown of the AC Voltage General Equation, Transmission Lines & Electricity Distribution, Understanding Input and Output Resistance, If we have a current (electron) moving in a conductor, the moving electron will induce a magnetic field around the wire. 3. An induction or asynchronous generator is an electric induction motor driven at speeds above its synchronous speed. Why would one be used? Advantages: An asynchronous generator is an AC . What is the obvious physical difference between the induction and synchronous motors? The hand help us determine the flow of current based on the moving magnetic fields direction (where the arrows point) and motion (which way does it move). . Thanks! Difference in Applications. We already have a great tool for this: the squirrel cage! I have explained the detailed overview about these two if you have any further query ask in the comments. In a generator, current is produced in the armature winding. 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. - Synchronous motor rotate because of magnetic locking between rotor poles and stator poles. A synchronous generator is an induction generator that is used to generate electricity by induction. An induction mot. 12) Speed, in RPM (revolutions per minute). 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. The rotor will rotate only at one speed in the synchronous generator unlike the induction motors. Speed of Synchronous motor is independent of the load and always runs at synchronous speed. The Permanent Magnet Synchronous Motor is mainly . 18) Rotor, whether squirrel cage or slip-ring; 9. Excellent. I am a professional engineer and graduate from a reputed engineering university also have experience of working as an engineer in different famous industries. If we add back the other two conductors, each being. The induction motor works on the principle of 'Electromagnetic Induction'. Working Principle of Synchronous generator : The alternators work on the principle of electromagnetic induction. First of all, what do we mean by machines? In a generator, on the other hand, the armature or windings of wire spin inside a fixed magnetic field to generate electricity. It consists of copper or aluminum bars embedded in the semi-closed slots resembling a squirrel cage. It has unity or lagging or leading power factor. These are AC motor (Synchronous & Induction motor) and DC motor (Series, shunt & compound motor). This works the same principle as in induction motors. . The magnetic field of the rotor is supplied by direct current or permanent magnets. Is synchronous generator same as alternator . Direct Current (DC) Excited Synchronous Motors. An Induction Motor is also known as Asynchronous Motor. 16) The altitude of the place in which the motor is intended to work if it exceeds 1000m. On the left we see the most simplistic scenario: 2-pole rotor and a 3-pole stator. The efficiency depends on the specific motor type and size, but the lack of slip in synchronous . - Synchronous motor required DC excitation to its rotor. When we have the same type of pole at the opposite side, the two sides are wired out of phase. the field points from outside in. As the name implies, the asynchronous motors are the ones whose speed is not equal to synchronous speed, i.e. This is a DC electromagnet. It can be operated under a wide range of power factors both lagging and leading. This is why induction motors are also known as asynchronous 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. The Lorentz Force will be symbolised by an arrow that come out from your palm. For AC machines, the basic requirement is to create a rotational magnetic field so that the rotor can rotate, and energy can be obtained. It is a handy tool to determine the direction of the current in a particular bar at a given point. Only stator is given 3 phase AC supply. Non-Excited Synchronous Motors are available in three designs: Example: Crushers, Rolling Mills, Steel Mills, Metal rolling mills, Pulps, Grinders. The induction motor has self-starting torque whereas the synchronous motor is not self starting. The rotating magnetic field induces a current flow in the squirrel cage bars based on the law of electromagnetic induction. It can be used as a synchronous condenser for power factor improvement. It is a hollow steel alloy that contains the 3-phase conductors rolled up in coils. Your our thumb will point to the direction of current flow. Schematics and operation of different types of motor. 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. 1. The rotor is not given any supply. We further classify it into three types; they are the induction motor, synchronous motor, the linear motor. Through this platform, I am also sharing my professional and technical knowledge to engineering students. This is the Right Hand Rule. It has to be run up to synchronous speed by any means before it can be synchronized to AC supply. Now we have a rotating magnetic field in the stator, which is around the squirrel cage. - Speed of synchronous motor is constant at all load. Electric motors, generators, alternators and loudspeakers are explained using animations and schematics. From the structural level, the structure of the permanent magnet synchronous motor is more complicated than that of the AC asynchronous motor, and the cost output is higher. 5. This motor is costlierthan the induction motor. 2. It works on the principle ofmagnetic locking. What we have is a coil. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); document.getElementById( "ak_js_2" ).setAttribute( "value", ( new Date() ).getTime() ); New users enjoy $54 free coupons after signing up at JLCPCB successfully, $54 coupons can also apply to 3D printing orders, for 3D printing special offer, it gets started at $1, Difference between cell splitting and cell sectoring, Differences Donor and Acceptor Impurities in Semiconductor, Wio-E5 and FREE Seeed Fusion PCBA Prototypes Campaign, DETAILED GUIDE TO GROUNDS, EARTH, AND GROUNDING ELECTRONICs, The AC motor that used the occurrences of the electromagnetic induction to generate the current and flux in the rotor to generate torque is familiar as the induction motor. It is used in motor-generator set requiring constant speed. Test your knowledge and practice online quiz for FREE! The hand help us determine the flow of current based on the moving magnetic fields direction (where the arrows point) and motion (which way does it move). A synchronous motor is a doubly excited machine. In power stations, generators are used to generate electricity. Differences between a 3-pole and a 6-pole stator winding. The Shaft of the motor is run by the magnetic force produces between armature and field windings, while in the case of . Consider a two-pole simple rotor (shown in the above figure). These are very important topics in electrical engineering. 3. They consist of 2 main parts: In addition, there are 3 important parts: In a case of a generator, the rotating shaft (prime mover in other names) is attached to a turbine. In a synchronous generator, the waveform of generated voltage is synchronized with (directly corresponds to) the rotor speed. They are the synchronous AC motor and induction AC motor. Induction motor has self starting torque. The synchronous motor has more power efficiency due to the unity or leading power factor. 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. We cant have the two N poles send the electrons against each other. What is the difference between a synchronous motor and a synchronous generator? The squirrel cage is essentially 2 circular plates that are joined by bars. FIGURE 1 Synchronous machine operating as a 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. Types: DC motor and AC motor. Key Difference: Synchronous motors and induction motors are the most widely used types of AC motor. Synchronous motors can achieve efficiencies of >90% in some cases and are generally more energy-efficient than induction motors. Essentially, we have a coil that is wrapped around the rotor. 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. It can be constructed with wider air gaps than induction motors which makes it better mechanically. Why Induction motors are called Asynchronous motors? 4. I work and write technical tutorials on the PLC, MATLAB programming, and Electrical on DipsLab.com portal. Different structure settings. (50 cycles per second). When we have the same . Runs at synchronous speed. It is used in constant speed application; the speed of the induction motor can be variable. The induction motor works on the principle of Electromagnetic Induction. It is not self starting. While Generators is a device that are used to convert mechanical energy into electrical energy. An AC generator that has working occurrences alike to the. Inputs to the machine . The asynchronous nature of induction motors . In an alternator, electricity is produced when a magnetic field spins inside the stator (windings of wire). If you have any queries, drop me a message in the comment section below. This is because the rotor, thus, these slip rings spin, and the only way to feed electricity in them is via brushes. Figure 4: Squirrel Cage (part of the rotor) in an Induction 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. Synchronous Motor Is A Doubly Excited Machine, Whose Armature Winding Is Energised From AC Source And Its Field Winding Is Energised From DC Source. For example water moves the turbine and it makes the prime mover spin. Dont forget, this is one wire. This magnetic field will interact with the 3-phase rotating field and the result is a force that starts to rotate the squirrel cage. Thanks for the Excellent explanation. - It is not self starting. As the name suggest, the synchronous motor has a rotor that is designed to rotate at the same speed as its stator rotating magnetic field called synchronous speed. Figure 8: Construction of a Synchronous Motor. Also covered the advantages and disadvantages of these two AC motors. (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. More about Induction Motors. Which is better induction motor or synchronous motor? Normally, for a solenoid (coil) one end is N and the other S with 180 between them. 3. Required fields are marked *. Squirrel Cage (part of the rotor) in an Induction Motor. Since it does not have exterior excitation circuitry and it cannot produce reactive energy (Q). S = (Ns-N) / Ns. The magnetic field can be easily drawn using the, A coil with current in it will have a North and a South magnetic pole. Construction of Synchronous Motor is Difficult. Advantages of Synchronous motors. Asynchronous generator is an alternator that utilizes air gap rotating magnetic field between stator and rotor to interact with induced current in rotor winding. Starting Position. 4 - Type of Torque in the Synchronous Motor. 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. Figure 1: Construction of a 3-phase induction motor. But in this case theres no more rotating magnetic field around the bars, as they move with the same speed. Synchronous Motor vs Induction Motor - Difference Between Induction Motor and Synchronous Motor.#Induction_Motor #Synchronous_Motor #Learning_Engineering#kon. Definitely, I will try to publish and share more tutorials and useful technical kinds of stuff. The Induction motor is also known as asynchronous motor because its rotor rotates at a speed less than the theoretical synchronous speed of the motor. Control voltage at the end of the transmission line by varying the excitations. The cage will start to rotate due to the Lorentz Force. AC machines (mostly synchronous machines) convert this rotation into 3-phase electricity. In these articles, we tried to provide all the necessary information regarding the difference between an Induction Generator vs. Synchronous Generator. It is so called because it never runs at synchronous speed. The motor is costly and requires frequent maintenance. A regular AC induction motor usually can be used as a generator, without any internal modifications. We can even have more poles. How to make the single-phase Induction motor self-starting? Hello, readers welcome to the new post. Publicado en . A synchronous motor is costlier than an induction motor of the same output and voltage rating. (especially three-phase induction motor). An induction generator produces electrical power when its rotor is turned faster than the synchronous speed. Mostly used in Single phase Induction motor. Both of these devices are working on the principle of Faraday law of electromagnetic induction. Sure, I will add the construction point in the comparison of both machines. If done so, the rotor poles get magnetically coupled with the rotating stator poles, and thus the rotor starts rotating at the synchronous speed. Motor is a device that used to transform electrical energy into mechanical energy. To come across this issue, we use the Star-Delta Starter method. Privacy. I always thought mixers and grinders used universal motors. I am also a technical content writer my hobby is to explore new things and share with the world. In 3 phase Induction, a motor Rotating Magnetic Field (RMF) is produced by supplying currents to a set of stationery winding (or) stator with the help of a 3 phase power supply. It is a highly efficient motor; The efficiency of the Induction Motor is from 85 to 90%. Keep up the good work. The induction motor does not require an excitation system to start the motor. ; 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. Dont forget, the magnetic field goes in a loop, but we consider the arrows that are outside the pole. 8. Your other four fingers will indicate the direction of the magnetic field. Speed. The synchronous motor works on the principle of the 'Magnetic Locking'. The different slip occurs in the induction motor. Lorentz Force Right Hand Rule. This is happening in all 3 phases. This is great for size-constrained applications and is a reason to choose a synchronous motor over an induction motor. Why NPN transistor is more used over PNP transistor? This happens so fast that what we witness in real life, is that the machine rotates a bit slower than the synchronous speed. These were the main motor and generator differences that can be asked in the exams. We said that the current in the bars are due to the constantly rotating magnetic field around. The turn is also in the opposite direction. So, these machines can either be generators or act as motors. Current comes in via the 3 phases and since it is alternating current it creates a rotating magnetic field in the stator. Ceiling fans, cars, etc. The rotor is still. The induction generator always rotates at more than synchronous speed (Nr>Ns). The same four-pole motor operating on a 50 Hz grid will have a . Motoris a device that used to transform electrical energy into mechanical energy. Figure 11: Differences between a 3-pole and a 6-pole stator winding. 5. Think of a steam or wind turbine, where the blades are attached to a rotating shaft. At high loads the power factor becomes very poor. Because their rotors never run with the synchronous speed. 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 The brushes only touch the rings. This means for example the North pole of the electromagnet will attract the South pole of the rotating magnetic field. The image shows the two states of the current and how it changes the magnetic poles accordingly. Current comes in via the 3 phases and since it is alternating current it creates a rotating magnetic field in the stator. i.e., Ns = 120f/P. The colours indicate each phase, The. DC motors. Principle. In this blog, we are talking about the difference between Synchronous and Induction AC Motor with the help of various factors, like the type of . the field points from outside in. Induction generator is a motor that uses electromagnetic induction between the rotors to induce current in the rotor to achieve electromechanical energy conversion. 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. This cage is next placed inside the stator. It is a device consisting of a number of capacitors connected in the motor circuit, it produces three output waves from a single input wave which differ in phase from each other. This motoris cheaper than the synchronous motor. Although, when there is a current in a wire (or bar in our case), the current will induce a magnetic field itself. What does a soft starter do? Thus, we can draw the N & S poles. The synchronous motor always runs at Synchronous speed Ns. Connected Supply. The Motor transforms electric power into mechanical energy, while the generator does the opposite. The Synchronous Motor requires the DC excitation system (or prime mover) to start the motor (i.e. This is comparatively more efficient than an induction motor, Its stator winding is energized from an AC Source, Its field winding is energized from a DC source and Armature winding is energized by AC Source. This is called slip. Based on the number of rotor poles we can distinguish between: In the above example we had an electromagnet as a rotor that had a North and a South pole (2 poles). In a synchronous electric motor, the rotation of the shaft is synchronized with the frequency of the supply current. The cage will start to rotate due to the Lorentz Force. No self-starting torque, so some other auxiliary means have to be provided for starting the synchronous machine. A motor is a device that converts Electrical energy into Mechanical energy. While synchronous motors have higher efficiency and no slip, induction motors have good starting torque. Thumb shows the direction of the current and the fingers indicate the direction of the magnetic field. Synchronous motors can be classified into two types based on how the rotor is magnetized. These are AC generator (Synchronous & Induction generator) and DC generator (Separately excited & self-excited). The squirrel cage Induction Motor makes an excellent generator when it is driven above its synchronous speed. Slip is the difference in speed between the rotor speed and synchronous speed of the rotating stator field; as the load increases in a motor, slip increases and the motor slows. Used in substations and industries to improve the power factor 2. The dc generators also work on the same principle. Its stator winding is energized from an AC source. Synchronous Speed / Advantages. A synchronous motor is costlier than an induction motor of the same output and voltage rating. The first electric motor was a simple electrostatic device by Scottish monk Andrew grandson and benjamin franklin in the 1740s. these motors run at a speed slightly less than the synchronous speed. Synchronous motors are mostly used in large generators, while induction motors are almost used as the motors to drive machines. For Synchronous motor, relative motion is not required in between the stator and rotor. Which motor is used in the washing machine? Figure 5: Flemings Right Hand Rule. What is Circuit breaker? Collector rings and brushes are required. 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 . There are 2 key kinds of induction motor rendering to the structure of the rotor of the motor, first single is the squirrel cage motor since its rotor construction is similar the squirrel and 2. A synchronous motor is a doubly excitation machine, i.e., its armature winding is connected to an AC source and its field winding is excited from a DC source. What is a Junction box, and its applications? Electric motors and generators. The rotor slots in this type of rotor are not parallel to the shaft instead they are skewed for obtaining a quick and smooth operation The rotor bar is connected at both the ends and short-circuited by solid rings made of copper, brass, or aluminum. So let get started Difference between Induction Motor and Induction Generator, That is all about the Difference between Induction Motor and Induction Generator. 3. The induction motor consists of a stator and a rotor. This conductor is rolled up in a coil. A three-phase synchronous motor is a doubly excited machine, whereas an induction motor is a single excited machine. Why Induction motors are called Asynchronous motors? The output frequency of an asynchronous generator is slightly (usually about 2 or 3%) lower than the frequency calculated from f = RPM x p / 120. This article presents top 10 differences between induction and synchronous motors. The basic idea for both induction machines and synchronous is very similar. In a motor, current is supplied to the armature winding. A synchronous motor can be operated with lagging and leading power by changing its excitation. By contrast, the induction motor requires slip: the rotor must rotate slightly slower than the AC alternations in order to induce current in the . Right picture: Both N points to an X and both S to a . By using the small pony motors like a small induction motor, we can start the synchronous motor. Higher Efficiency especially in low-speed unity power factor. Now, instead of a North and a South pole, we have two of each. Portable, inverter, and standby: Working principle As mentioned before, in the case of a generator, the rotor needs to be turned with half the speed to generate the same frequency as in the 2-pole rotor setup. 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. Synchronous motor is preferred for driving the load requiring high power at low speed, Excessive and unbalanced starting currents. Because their rotors never run with the synchronous speed. Key Differences Between Motor and Generator. Application: Used in pumps, compressors, paper mills, textile mills, lathes, Drilling machines industrial drives. Thank you so much, Mohammed Imran. A more-specific explanation of how . Difference between a 2-pole rotor ,3-pole stator machine and a 4-pole rotor, 6-pole stator machine. This force will make the cage rotate. Because initially the cage is static and all a particular bar sees is a constantly changing North & South poles (from the rotor). 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. This works the same principle as in induction motors. When they approach synchronous speed, the slots enable the synchronous magnetic field to lock onto the rotor. However, the permanent magnet synchronous motor has a smaller volume and a lighter weight. 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. A Synchronous motor is a double exciting machine i.e., two electrical inputs are provided to it. As this generator usage reactive energy so there must be an outdoor reactive power source that must be linked with it to provide a field at the stator. So, far we covered how Induction Motors work. 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. The speed is always less than synchronous irrespective of the load. So, the wire goes from outside-in, and on the opposite side inside-out. Zero slip (S=0) occurs in the synchronous motor. All Rights Reserved. I am promising, will share more posts like this. 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. Based on the principles of electromagnetic induction, the first induction motors were invented by Nikola Tesla (in 1883) and Galileo Ferraris (in 1885), independently. Yet the change of magnetic field (synchronous speed) would still be 50 times/s. These two AC motors are-. 2. Thanks, Mathew Varghese. What are factors need to be considered while choosing a motor? In factories having a large number of induction motors or transformers operating at lagging power factor, it is used for improving power factor. @2020 - automationforum.co. s is the slip, Ns is the magnetic field speed, n is the rotor speed. The stator generates a rotational magnetic field upon supply alternating current. Synchronous Machine. The idea is that this time the rotating shaft (. Some are dc motors and some as ac motors and generators and perform different functions. So, both synchronous and induction machines can be used as generators or motors. We have a 3-phase AC in the stator. What are the types of Synchronous motors? 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. Excitation of Induction Motor. The main difference between them is in regard to what spins and what is fixed. 2. Synchronous motor. Synchronous generators are controllable by governors which monitor system frequency and adjust prime mover input to bring correction to frequency . It is more efficient than an induction motor of the same output and voltage rating. As the current alternates, so does the direction of the magnetic field and poles. Great source of knowledge please share as much as you can. Which is more efficient induction motor or synchronous motor? It cant be started under loaded conditions; its starting torque is zero. The speed is independent of load. Runs lower than synchronous speed. In the first picture, one side of the rotor is N and the other is S. In the 4-pole case, the opposite side of the North pole is another North pole. We need something that initially gives a kick for the rotor to start rotating so it can lock onto the 3-phase field. 1. The colours indicate each phase, The direction of the current is usually denoted by an arrow, so the X means it is going in the page, whereas the dot means coming out. Induction generator takes reactive power from the power system for field excitation. . Used in powerhouse and substation in parallel to the bus bars to improve power factor, for this purpose, it is run without mechanical load on it and overexcited. Figure 6: Lorentz Force Right Hand Rule. Note, we have AC in the conductor meaning the current, thus, the magnetic field too will change directions 50 times a second: Figure 3: The image shows a single phase isolated in the stator of a 3-phase motor. Using Damper Winding as a Slip Ring Induction Motor (Synchronous InductionMotor). This field will have a direction. There are various types of motors available as classified below. Synchronous Motor always runs at synchronous speed, and the speed of the motor is independent of load, but an induction motor always runs less than the synchronous speed. Additional damper winding is necessary. 4. On the right, we have a 4-pole rotor with a 6-pole stator. This field induces a current in the bars. Figure 7: Star and Delta connection of a 3-phase motor. So, in a 2-pole scenario, the rotor rotates 50 times per second to generate 50Hz electricity. But the induced current itself in each bar will have its own magnetic field that will repel the stators field, thus, creating a force. When an Induction Motor is connected to 3-phase power, the magnetic field starts to rotate instantaneously. s = (ns-n) / ns. 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. It can be operated under a wide range of power factors both lagging and leading. The induction motor does not require an excitation system to start motor. Now we discuss these two main parts and some sub-parts of induction motor with the details. As the N & S poles rotate, so will the current change direction in each bar. North South North -South. It runs at less than 1500 rpm. Speed. 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. Different types of motors are used in industries and homes according to their construction and use and features. Figure 11: Differences between a 3-pole and a 6-pole stator winding. You are doing smart job to give simple understanding electrical terms keep it up. In the case of a 4-pole setup, the rotor only has to turns 25 times to generate the same 50Hz. It means that only a single source . An induction motor is cheaper than the synchronous motor of the same output and voltage rating. The difference between the excitation of the induction motor and the synchronous motor is that the induction motor is a singly excited machine. When DC supply is given to the rotor it acts as an electromagnet. MV = High Efficiency +1~2%. So, no current, no force. An induction motor is used for driving mechanical loads only. It is essentially a coil where you start rolling up a wire at one end and finish it up the other. 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 leads to the rotor to slow down. Similarly, it also consists of two main parts- the stator and rotor. Its efficiency is lesser than that of the synchronous motor of the same output and the voltage rating. 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 . These are connected to an external power source via brushes. for the rotor rotating). Both of these devices are working on the principle of Faraday law of electromagnetic induction. The rotating magnetic field induces a current flow in the squirrel cage bars based on the law of electromagnetic induction. Application: 1. A synchronous motor can run . It is always less than the synchronous speed. 1. It can be constructed with wider air gaps than induction motors which makes it better mechanically. are all examples of motors. It is used for power factor correction, constant speed load service. Save my name, email, and website in this browser for the next time I comment. Use the Right Hand Rule to see the magnetic field. Electricity is employed in the motor, but the generator creates the electricity. Note, it is heading in a different direction inside the cage than outside (blue arrows). The major difference between Motor and Generator is that a motor converts electrical energy into mechanical energy, whereas the generator does the exact opposite. There are two chief parts the induction motors first one is the stator which is the stationary portion of the induction motor and supply voltages are provided at those parts. 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. They are also widely used as 3-phase generators. 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. And other low mechanical power applications. We will end up with something like this: Figure 9: 4-pole rotor of a 3-phase synchronous generator. Higher Efficiency especially in low-speed unity power factor. Its speed cannot be varied without sacrificing some of its efficiency, Its speed decreases with the increase in load. . For North poles. . The trick is to disconnect the slip rings initially while the cage is in action, next, once the rotor is spinning, we connect them back and the fields will lock. The slip will be negative and the current will be generated in the opposite direction, meaning, electrons will flow back in the supply. Amazing article. Difference between synchronous generator and induction generator. Many times you will be asked to compare these two types of motors. Why? 7. Current, which is the flow of holes or in other words the absence of electrons, flow in the opposite direction. What information is learned in a locked-rotor test? synchronous speed. But hey, once the rotor slows down, the magnetic field seems to rotate again and we start the whole process from the beginning. Hence synchronous motor rotates at constant speed i.e., synchronous speed. Copyright 2019 Engineering Scribbles | ALL RIGHTS RESERVED, Electronic & Electrical Engineering Basics. (especially three-phase induction motor) 05. This field induces a current in the bars. As the current alternates, so does the direction of the magnetic field and poles. the difference between the synchronous speed and the rotor speed is called . the motor/generator acts as a motor. Although, in real life it looks more like in Figure 6. Very simple and almost unbreakable construction in squirrel cage type. In a synchronous generator, the waveform of generated voltage is synchronized with (directly corresponds to) the rotor speed. the difference between the synchronous speed and the rotor speed is called . (It is not self-starting). The first generator was invented by Michael Faraday in 1831. means it is going in the page, whereas the dot means coming out. This rotating magnetic field will induce a current in the squirrel cage bars based on electromagnetic induction. If the turbine turns 50 times per second, the output voltage will have a frequency of 50Hz! The electromagnetic motor which converts electrical energy into mechanical work at variable speed is called as a Induction Motor. 4. If the conductor is part of a closed circuit, this force will move electrons and current will flow. This separate source also controls the output voltage of the generator, this generator does not have the capacity to regulator its terminal voltages. Note: Induction motor is called the Asynchronous Motor. Conveyor belt, rolling mill, mixer, grinder are an example of the induction motor. Induction motor runs at the non-synchronous speed. If the frequency of the A.C. supply is Hz and the stator is wound for the P number of poles, then the speed of the rotating magnetic field is synchronous. Here we will discuss the Difference between Induction Motor and Induction Generator. It is a rotating part of the Induction Motor which is placed inside the stator, an air gap between the stator and rotor separates them from each other allowing the rotor to rotate freely. This force will make the cage rotate. The stator contains slots for a uniformly distributed field winding in an induction motor while the rotor carries the armature winding. Current, which is the flow of holes or in other words the absence of electrons, flow in the opposite direction. The stator is the stationary part of the machine. Power factor is lagging in induction motor and unity in synchronous motor. AC Motors are mainly of two types, one is synchronous motor, and the other is an asynchronous motor.Asynchronous motor is also known as an induction motor.Both Motors are widely used electric motors. Hope this will help you for the preparation of the exam or interview. We define the North and the South poles based on the magnetic fields direction outside the cage. What information is learned in a . AC machines are based on the principle of electromagnetic induction. Induction machines, also called asynchronous machines are slightly lagging behind the synchronous speed. The induction motor is mostly used in industrial applications. In the supply system of the induction motor, stator winding is linked by an AC source. The main difference between these 2 motors is that synchronous motor rotates on a constant speed that is similar to the stator's rotating field speed. Induction generators operate by mechanically turning their rotors faster than synchronous speed. post-graduate in Electronics & communication. Dont forget, the magnetic field goes in a loop, but we consider the arrows that are outside the pole. A Three-phase induction motor is a single excited AC machine. They operate at a more simplistic principle and theyre also cheaper to manufacture. Dear Ms. Dipali Chaudhari, Both Induction and Synchronous motors are widely used in electrical industry. What are various Pressure calibrators and how to, Errors Involved in Pressure Gauge Measurement, What are the types of industrial sensors used, Instrumentation Interview Question And Answers, Industrial Automation Interview Questions And Answers, Electrical Interview Questions And Answers. The synchronous motors always run at a constants speed which is called synchronous speed. Flemings Right Hand Rule. In AC supply, single-phase and three-phase motors are available. The current will induce a magnetic field around the wire based on the Right Hand Rule mentioned above. Synchronous motors include two electrical inputs, making them doubly excited machines. The speed is always less than synchronous but never synchronous. This is because both magnetic fields point at the same direction and will repel each other. The rotor speed of the induction motor is continually less than the synchronous speed, so the motor continually runs at a speed fewer than the synchronous speed. The image shows a single phase isolated in the stator of a 3-phase motor. The induction motors are the types of asynchronous motors. Also, here is a good video that explains more about a Star & Delta starter. There are so called slip rings attached to the pole. We also know that the rotating shafts speed will slightly lag behind the synchronous speed. We came up with the basic definitions of what are induction and synchronous generators . A cross-section of the Induction motor is shown below, An Induction Motor basically consists of two parts. Since, the field is excited by the power system, the synchronous generator can deliver only real/true power but absorbs the reactive power. Here, Im comparing synchronous motor and asynchronous motorwith their specifications, functions, applications, and examples. An induction motor is cheaper than the synchronous motor of the same output and voltage rating. To make motor self-starting, during starting period the motor is temporarily converted into a two-phase motor, For this purpose stator of a single-phase motor is provided as extra winding, known as starting (or) auxiliary winding addition to the main or running winding. But this all depends on the existence of magnetic locking between stator and rotor poles. 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. So, for example, if our turbine turns 50 times per second, the induction machine will generate only 45Hz. Its speed is independent of the load. 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. It cant be used as a synchronous condenser. What is the application of Synchronous Motors? The current-carrying windings produce the magnetic field or flux, three sets of flux produced due to power supply, resultant flux has a constant magnitude and its axis rotating in space without physically rotating the windings. This is the Right Hand Rule. Here is a good YouTube video that visualise Lorentz Force in action. Can a 3phase motor be run on a single-phase line? The ac voltage is . 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. The difference between the two types is that the synchronous motor rotates at a rate locked to the line frequency since it does not rely on current induction to produce the rotor's magnetic field. Especially the independent operation of induction generator makes . The same four-pole motor operating on a 50 Hz grid will have a . The induction motor is less efficient than the synchronous motor. The cage has a rotating field around (which is from the 3-phase windings in the stator). This RMF rotates with synchronous speed. Based on the number of rotor poles we can distinguish between: 4-pole rotor of a 3-phase synchronous generator. Single phase induction motors arenot a self-starting motor, and three phase induction motor are a self-starting motor. 2. Lets take the example that we have in the picture. Based on the number of rotor poles we can distinguish between: . The construction of the synchronous motor is very difficult. The stator carries a 3-phase winding while the rotor . What techniques are available to start a synchronous motor? Sharing my knowledge on this blog makes me happy. Your. No DC field current is required. Construction of Induction Motor is relatively easy. What if we used the same wire and wrap it around 4 poles instead? Requires DC excitation supplied from external sources. Its armature winding is energized from an AC source and its field winding from a DC source. The stator winding of Induction Motor is energized from an AC source. Synchronous motors are costlier, almost 25% of the motors cost goes to rotor windings, but induction motors are cheaper. The current will induce a magnetic field around the wire based on the Right Hand Rule mentioned above. The direction of the current in the cage bars will vary back and forth with the rotating magnetic field. S - slip, Ns - the magnetic field speed, N - the rotor speed. The induction motor always runs at speed less than its synchronous speed. Although, in real life it looks more like in Figure 6. The speed is slightly higher than the synchronous speed. Lets see what the biggest difference is. 2) Reference to this standard, that is, Indian standard/European standard. So, the wire goes from outside-in, and on the opposite side inside-out. The motor then turns at synchronous speed so long as the required torque is low. The induction motor has a simple design, while the synchronous motor has a complex design. Thank you for explaining the differences between Induction motors & Synchronous motors in simple terms. 04. The induction generator has numerous limits. Note, it is heading in a different direction inside the cage than outside (blue arrows). In this post, we are learning the difference between the two types of alternating currents (AC) motor. Use the Right Hand Rule to see the magnetic field. 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. A synchronous motor/generator has a rotor with either a permanent magnet or an electromagnet energized through slip rings from an external DC source. What are the differences between the Induction motor and the Synchronous motor? The motor that converts the alternating current into mechanical power by using an electromagnetic induction phenomenon is called an AC Motor.Mainly an AC motor classified into two types. Your email address will not be published. The rotor of a synchronous motor behaves like permanent magnetic or electromagnetic and its field interacts with . Please share more knowledge regarding the induction motor for an electrical Design point of view. An induction motor operates only at a lagging power factor. Synchronous motors are generally more efficient than induction motors. The motor cant use in such applications where high starting torque is necessary. Synchronous speed be contingent on the number of poles of motor and frequency of input voltages. for the rotor rotating). difference between slip rings and commutator. The synchronous motor works on the principle of the Magnetic Locking. It is self-starting the 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. Also, Read: . For North poles. Very easy to understand the way you compare both motors. When we have the same type of pole at the opposite side, the two sides are wired out of phase. Rao Kattoju, Thank you very much, Veerabhadra for your kind words. 14) Unidirectional or bidirectional rotation requirements. It is self-starting the motor. 1. Difference Between Induction Motor And Synchronous Motor. 5. The power factor is very low during light load conditions. Synchronous motor. And could cause a drop in the grid, so taking current away from other devices. "f" is the frequency of the output of the generator. The synchronous speed of a stator rotating magnetic field depends on the supply frequency and the number of poles for which stator winding is wound. A Single-phase induction motor is not self-starting, It requires some support for starting. our thumb will point to the direction of current flow. All Right Reserved. In a 4 pole scenario the N and S poles change every 90. It is basically the same as induction motor. - Power factor can be changed from lagging to leading and vice versa. In industries, households or for power group purposes the 3-phase squirrel induction motor is typically cast-off, due to its consistency, less price, and self-stating stuff. The synchronous motor requires the DC excitation system (or prime mover) to start the motor (i.e. where N is speed of the rotor in rpm and P is number of poles. 3. aspen school district calendar difference between slip rings and commutator.
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