Comparison between Synchronous and Induction 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. A squirrel cage rotor from an induction motor. Image Courtesy: mark5150.deviantart.com, dongye-cn.en.made-in-china.com. The inside rotor is attached to the output shaft which produces a second rotating magnetic field. Induction motors dont require a DC power source for the rotor excitation. The output power increases or decreases with the slip rate. Three-phase induction motor operates on induction principle. It has to be run up to synchronous speed by any means before it can be synchronized to AC supply. According to the power supply, the motors are classified as AC motor and DC motor. No commutator or brushes, or other connecting mechanism is used to supply current to the rotor. Single-phase induction motors are used extensively for smaller loads, such as household appliances like fans. Most modern induction motors have a rotor in the form of a squirrel cage. Your email address will not be published. Difference Between Induction Motor And Synchronous Motor. Induction motor requires no dc excitation to the field and hence it is singly excited machine. Yet the rotational speed of the rotor is slower than the input power source frequency. Synchronous motors require DC current to create the field in the rotor windings; induction motors are not required to supply any current to the rotor. As for the rotor winding, it does not induce current during the normal rotation of the motor and also does not participate in the work. - Synchronous motor required DC excitation to its rotor. : No.598 Binhe Rd, Hangzhou, China 310052, Add: No. Post category: Electrical / Electrical Study Material; Continue Reading V Curve of a Synchronous Motor. In the supply system of the induction motor, stator winding is linked by an AC source. It is a self-starting motor, it starts from rest up to its full speed without any other source. 4 - Type of Torque in the Synchronous Motor. Comparatively, the motor is costlier. The induction motor always operates at a lagging power factor. (mechanical for motor, electrical for alternator) Now, the difference between a synchronous machine and an induction . The induction motor is a widely used motor in industries. Squirrel Cage Induction Motor Troubleshooting, Tendency of Synchronous Motor Application, Synchronous Motor: Definition, Features and Comparison, Differences between Synchronous and Asynchronous Motor. Rotor winding is fed with a DC supply with the help of slip rings. Synchronous motors can be constructed with permanent magnets in the rotor eliminating the slip rings, rotor windings, DC excitation system and power factor adjustability. As any motor, it uses magnetic forces to rotate the rotor. AC motors are divided into two types, synchronous motors and asynchronous motors which are also called induction motors. Your email address will not be published. 4 - Type of Torque in the Synchronous Motor. An induction motor operates only at a lagging power factor. The asynchronous moniker arises from the slip between the rotational speed of the stator field and somewhat slower speed of the rotor. - Synchronous motor rotate because of magnetic locking between rotor poles and stator poles. Therefore, it is self-starting and doesnt need an induction winding to start it. Synchronous motors operate at synchronous speed (RPM=120f/p) while induction motors operate at less than synchronous speed (RPM=120f/p slip), and slip is almost zero at zero load torque and the slip increases with the load torque. It means that only a single source is enough for its operation. What is a synchronous motor. Figure 11: Differences between a 3-pole and a 6-pole stator winding. Synchronous motors require a starting mechanism in addition to the mode of operation that is in effect once they reach synchronous speed. Copyright 2022 ATO.com. Synchronous motors require rotor windings, Induction motors are most often constructed with conduction bars in the rotor that are shorted together at the ends to form a squirrel cage.. An induction motor operates only at a lagging power factor. Induction motors are generally less efficient than synchronous motors. While AC induction motors are more commonly found in motor-driven systems, they are often larger in size and less efficient than permanent magnet motor solutions. Required fields are marked *. What is difference between induction and motor? It only serves to start the motor.During the steady-state operation of synchronous motor, there exists a constant relationship between the rotor rotating speed and the grid frequency: N = Ns = 120f / p f - the grid frequency, p - the motor pole number, Ns - synchronous speed.2. Difference Between | Descriptive Analysis and Comparisons, Counterintelligence Investigation vs Criminal Investigation, Samsung Galaxy S4 Active vs Nokia Lumia 925, Programming Language vs Scripting Language. In a synchronous generator, the waveform of generated voltage is synchronized with (directly corresponds to) the rotor speed. The powering-on rotor bar is subjected to electromagnetic force in the rotating magnetic field, thus the rotor overcomes the rotation of load torque and accelerates its rotation. The difference between the excitation of the induction motor and the synchronous motor is that the induction motor is a singly excited machine. In wound rotor, windings are also permanently short-circuited, hence no slip rings are required. Because of this, induction motors are typically unable to maintain a constant speed under variable load torque applications. Synchronou motors require additional starting mechanism to initially rotate the rotor near to the synchronous speed. The synchronous motor always runs at a constant speed called synchronous speed. The direction of this induced current is such that it will tend to oppose the cause of its production, i.e. When the electromagnetic torque is equal to the load torque, the motor rotates at a constant speed.Induction motors rotating speed (stator speed) is slower than the rotating magnetic field speed, and this difference is called "slip", expressed by the percentage of synchronous speed:S = (Ns-N) / Ns. frequency. Since it operates on the principle induction, therefore, asynchronous motor is also known as Induction motor. Compare the Difference Between Similar Terms. Differences Between Synchronous & Induction (Asynchronous) Motor. Thus, the rotor will try to catch up with the RMF and reduce the relative speed. Induction motors dont require slip rings. Synchronous motors require slip rings and brushes to supply rotor excitation. The induction motor has self-starting torque whereas the synchronous motor is not self starting. This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. If done so, the rotor poles get magnetically coupled with the rotating stator poles, and thus the rotor starts rotating at the synchronous speed. AC motors can be divided into two main categories (i) Synchronou motors and (ii) Asynchronous motor. Induction motors don't require slip rings. An electrical machine which converts electrical energy input into mechanical energy output is known as electric motor. The induction motor is a type of single excited machine, whereas, the synchronous motor is a type of doubly excited machine. Induction motor is smaller in size for same rating and is a rugged and simple to handle motor. Both Induction motors and synchronous motors are AC motors used to convert electrical energy to mechanical energy. Difference Between Servo Motor and Induction Motor, Difference Between Synchronous and Asynchronous Motor, Difference Between Active and Passive Components. Difference in ConstructionThe stator windings of synchronous and induction motors are alike, and the main difference lies in the structure of the rotor. The synchronous speed is the constant speed at which the motor generates the electromotive force. It is used in constant speed application; the speed of the induction motor can be variable. An asynchronous motor is popularly called as Induction motor. The induction motor has a simple design, while the synchronous motor has a complex design. The armature winding of the synchronous motor is energized from an AC source and its field winding from a DC source. 1. Know about the differences between Synchronous and Induction AC Motor in terms of various factors like the type of excitation, in this detailed guide Skip to navigation Skip to content 1800 266 6123 So, both synchronous and induction machines can be used as generators or motors. This material has a wide hysteresis loop, that is, once it is magnetized in a given direction, it requires a large reverse magnetic field in the opposite direction to reverse the magnetization. The stator of the induction motor consist of wound poles which can be connected directly to the grid or via a VFD. What is the difference between induction motor and synchronous motor? However, induction motor power factor is not adjustable, so in some large factories, for the more applied induction motors, a synchronous motor can be added as a phase modifier, to adjust the power factors of the factory and grid interface. Unlike large synchronous motors, an induction motor does not require mechanical commutation, separate-excitation or self-excitation for the energy transferred from stator to rotor. So, guys, these are some differences between the synchronous motor and induction motor. close menu Language. Synchronous motors require slip rings and brushes to connect the rotor to the power supply. This provides the second synchronized rotating magnet field. This means that induction motors require less external peripherals to work effectively, bringing down both their cost and complexity. The Speed of the motor, starting and operation, the efficiency of both the motors, its cost, usage, and applications. Actual Difference Between Synchronous Motor and Induction Motor - Read online for free. Synchronous motorThe synchronous motor rotates for the interaction between the rotating magnetic field produced by the powering-on stator windings and the magnetic field the rotor generated. If you are doing preparation for the exam, viva, or interview, you will be asked questions- synchronous vs induction motors. Important Differences Synchronous motors need an additional DC power source for energizing rotor winding. It is not a self-starting motor; it needs external means to provide the necessary (synchronous) speed. Difference in Working1. Slip rings and brushes are required in synchronous motors. If the rotor's rotation speed and the stator's field speed are the same, it is called synchronous motor; if not, it is asynchronous motor. A synchronous motor always runs at synchronous speed, while an induction motor runs at a speed less than the synchronous speed. Therefore, as a motor, the induction motor is the choice at the most time. The rotor is fed with a DC supply. Induction motors must always operate with a lagging power factor. Induction motor:Stator winding is similar to that of a synchronous motor. 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. Induction motors can be of single-phase and three-phase. Whereas induction motors never require any added source of power. What is the difference between synchronous and induction generator? As you can see, induction and synchronous motors, while both classified as AC, have some rather diverse constructional and operational characteristics, with the presence of slip being the most prominent factor. Brushless DC motors are similar to AC synchronous motors. Whereas IM cannot be used to improve the power factor. This is why induction motors are also known as asynchronous motors. AC Induction Motor. 3 phase induction motors are self starting but . Cost and Maintenance - The SM is very costly and synchronous motor frequent maintenance is required whereas the cost of IM is cheap and the maintenance of motor is not required. Based on the principles of electromagnetic induction, the first induction motors were invented by Nikola Tesla (in 1883) and Galileo Ferraris (in 1885), independently. There are three main types of synchronous motors; permanent magnet motors, hysteresis motors and reluctance motors. The relative speed between stators rotating magnetic field and the rotor will cause an induced current in the rotor conductors. The rotor is placed within the cylindrical cavity of the stator, but not electrically connected to any external circuit. Induction motors dont require slip rings, but some induction motors have them for soft starting or speed control. When an Induction Motor is connected to 3-phase power, the magnetic field starts to rotate instantaneously. For AC machines, the basic requirement is to create a rotational magnetic field so that the rotor can rotate, and energy can be obtained. What is a synchronous motor Synchronous motors are costlier, almost 25% of the motors cost goes to rotor windings, but induction motors are cheaper. Difference in ApplicationsSynchronous motors are mostly used in large generators, while induction motors are almost used as the motors to drive machines. While permanent magnet motor solutions tend to have a higher initial cost, they may offer a smaller size for more compact mechanical packages and, more importantly, higher efficiencies. RECENT ARTICAL. The induction motor can never run on the synchronous speed instead it is always slower than the synchronous speed and it depends on the slip of the motor. In a synchronous electric motor, the rotation of the shaft is synchronized with the frequency of the supply current. Its speed can be controlled using a separate circuit. For PM synchronous motor, it rotates by the driving torque generated by the interaction between the rotating magnetic field of the stator and the secondary magnetic field of the rotor. As previously stated, induction motors are generally self-starting while synchronous motors are not. The output power increases or decreases with the slip rate. As the machine starts, the rotor naturally locks up with the rotating magnetic field and . Permanent magnets made of neodymium-boron-iron, samarium-cobalt, or ferrite is used as the permanent magnets on the rotor. Synchronous motor is the other major type of AC motor. The synchronous motor is used for converting the electrical energy into mechanical energy. Difference Between Induction and Synchronous Motor is explained with the help of various factors, like the type of excitation used for the machine. Synchronous motors include two electrical inputs, making them doubly excited machines. The connections in the stator coils are arranged in a way that opposite poles are generated at the exact opposite side of the stator coils. The power factor of a synchronous motor can be adjusted to lagging, unity or leading by varying the excitation, whereas, an induction motor always runs at lagging power factor. where N is speed of the rotor in rpm and P is number of poles. Read through this article to find out more about synchronous motors and induction motors and how they are different from each other. Put electrical energy in and you get mechanical energy out. However, the rotor windings of induction motor is short-circuit, which produce current by electromagnetic induction. No starting mechanism is required in induction motors. 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