This article describes the theory and operation of a three phase ac induction motor. The stator has a three phase stationary winding which can be either star connected or delta connected. They are truly elegant machines in that there are no moving parts except the rotor, and there are no brushes, commutators, or slip rings to wear out. Rotor has a winding the same as stator and the end of each phase is connected to a slip ring. As their name suggests, 1 phase ac power supply is extended to single phase induction motor while three phase induction motor is connected to 3 phase. Introduction three phase induction motor is the most popular type a. Watch this video to understand the working principals of the three phase induction motors. Advantages of 3 phase induction motor generally easy to build and cheaper than corresponding dc or synchronous motors. Introduction to induction motor instrumentation and control.
While materials and insulation systems have changed, the basic principles and operation of an electric. In the case of three phase ac alternating current operation, the most widely used motor is a 3 phase induction motor, as this type of motor does not require an additional starting device. When the 3 phase supply is provided to the stator, a magnetic field is produced which rotates the rotor and motor. The power line available for industries is 400v50hz three phase four line ac power and the inductions motors which work on this supply in industries are called three phase induction motors. You should also make a dc measurement of stator winding linetoline resistance. A 3 phase induction motor can be used for different applications with various speed and load requirements. The 3 phase induction motor is popular for its efficiency and is widely employed in the electric systems for doing mechanical work. For information on three phase, you can read my article on 3 phase. An induction motor can be, squirrel cage induction motor. A simple explanation of how a 3 phase induction motor works. When three phase stator winding of an induction motor is energized from a 3 phase supply, a rotating magnetic field is set up which rotates around the stator at synchronous speed ns. A three phase induction motor is basically a constant speed motor so its somewhat difficult to control its speed.
The basic idea of an electric motor is to generate two magnetic fields. Hi all, let us begin the course on induction motors, in this video, we will have an introduction and basic construction concepts. Introduction to induction motor the engineering projects. Assuming that the stator resistance r1 is measured at dc and that phase power. Difference between single phase and three phase induction motor the single phase and three phase induction motor is differentiated on the various factors in this article such as the supply on which they operate, their starting torque, maintenance, features, the efficiency of the motor, their power factors and the example where the two motors are used.
Induction motor basics, single phase and three phase induction. At synchronous speed, the slip is zero and hence torque developed by the. The three phase supply current produces an electromagnetic field in the stator winding which leads to generate the torque in the rotor winding of three phase induction motor having magnetic field. These types of motors are known as selfstarting induction motors. Ie2 series three phase asynchronous induction motor.
Three phase induction motors draw six or more times rated current when started at rated voltage. There are two types of induction motors, one is named as single phase induction motor, while the second one is named as 3 phase induction motor. These motors are selfstarting and use no capacitor, start winding, centrifugal switch or other starting device. It has been estimated that 70% to 80% of all electricity in the world is consumed by these motors. The rotor is separated from the stator by a small airgap which ranges from 0. Introduction types of electrical machines types of 3 ph induction motor basic principle working principle compnents of induction motor application comparision between 1ph i. Induction motor working principle single phase and three. Record all nameplate information for the induction motor.
In a 3 phase ac induction motor, there are three stator windings, each usually in two halves, with the rotor winding shortcircuited by end rings. In our industries and household, 3 phase induction motors are used. Slip, s, is defined as the difference between synchronous speed and operating speed, at the same frequency, expressed in rpm, or in percentage or ratio of synchronous speed. An electric motor converts electrical energy into a mechanical energy which is then supplied to different types of loads. They run at a constant speed from noload to the full load. Three phase motors are a selfstart and as we studied in a single phase induction motor article it needs capacitors to start its operation. We also discuss the construction of a three phase motor including its. Introduction the three phase induction motor is the extensively used for various kinds of industrial drives. So the rotor speed will depend on the ac supply and the speed can be controlled by varying the input supply.
Rotating magnetic field in 3 phase induction motor your. Various regulatory authorities in many countries have introduced and. Ac induction motors are also the most common motors used in main powered home appliances. Such high currents may pose serious problems for the motor and the electrical system when large motors are started. All cooling ribs of motors assume vertical or horizontal. Induction motor basics, single phase and three phase. One single phase wattmeter plus miscellaneous apparatus as needed. Among of them, the frames and endshields of the frame size from h63 to h2 are made of cast iron or aluminiumalloy,and the frames of h160 or over are made of cast iron with sufficient mechanical strength. Introduction three phase induction motors are the most common and frequently encountered machines in industry simple design, rugged, lowprice, easy maintenance wide range of power ratings.
This is the principle of operation of an induction motor of any type. The rotor will constantly be turning to align its magnetic field with that of the stator field. Circuit diagram of smoother start for three phase induction motor using pic microcontroller is shown below. The induction motor rotates due to the rotating magnetic field in 3 phase induction motor, which is produced by the stator winding in the air gap between in the stator and the rotor. China ie2 series threephase asynchronous induction motor. Three phase ac induction motors are widely used in industrial and commercial applications. There are a lot of applications of 3 phase induction motor, to name a few 1. Induction motor is an ac electric motor, having a stator and a rotor just like other motors, but the working principle is a little different which would be discussed further. The topic lies under the basic electrical and electronics engineering course that. For reason of economy, most houses, offices and also rural areas are supplied with single phase a.
As the current passes through the coils on opposite sides of the stator, a twopole electromagnet is established, creating a twopole motor. In todays post, we will have a look at three phase induction motor construction, working, slip, torque and other parameters. Three phase induction motors are the workhorse of industry. Single phase induction motor the engineering projects. It has good speed regulation and high starting torque. Whenever the ac supply is connected to the stator windings, line currents i r, i y, and i b start flowing. Difference between single phase and three phase induction. One way to reduce the starting current is to start the motor at reduced voltage. There are two basic reasons for the use of single phase motors rather than 3 phase motors. An electrical motor is an electromechanical device which converts electrical energy into mechanical energy. These are of two types, squirrel cage and slip ring motors. A 3 phase induction motor has two main parts i stator and ii rotor.
An induction motor or asynchronous motor is an ac electric motor in which the electric current. So initially motor starts slowly and then reaches its full rated speed gradually. The 3 phase set of currents, each of equal magnitude and with a phase. The 3 phase induction motor has two main components, such as any other motor. Introduction to induction motor the engineering knowledge. Parts of an induction motor three phase induction motor. Hi friends, i hope you all are fine and doing great with your lives. The induction motor is started by itself that we know. This is how easy it is to implement smooth starter for three phase induction motor. Describe the operation of an induction motor three phase ac power is supplied to the stator, creating a rotating magnetic field constant in magnitude and rotates at a constant speed. Before discussing the methods to control the speed of three phase induction motor one should know the basic formulas of speed and torque of three phase induction. A three phase induction motor runs on a three phase ac supply.
The main drawback of dc motors is the presence of commutator and brushes, which require frequent maint. Introduction to three phase motors flashcards quizlet. Way more information than you ever wanted on how to fell a tree. The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. Difference is that transformer is an alternating flux machine while induction motor is rotating flux machine. Enter the rated volts, amps, power, and efficiency to find the current flowing through the motor. Introduction to induction motor instrumentation and. Induction motor 1 chapter 3 induction motor bee23 electrical machine power system 2 learning outcomes. Rotating flux is only possible when 3 phase voltage or poly phase which is 120 degree apart in time is applied to a three phase winding or poly phase winding 120 degree apart in space then a three phase rotating magnetic flux is. The first ac commutatorfree threephase induction motors were.
The winding resistance causes copper losses in the windings, the windings inductive resistance cause a voltage drop power factor. Product introduction this series motors amount to the sixteenth frame sizes. Explain starting methods of 3 phase induction motor. Today, i am gonna give you an introduction of a single phase induction motor. Perform an analysis on induction machines which is the most rugged and the most. A three phase induction motor is a type of ac induction motors which operates on three phase supply as compared to the single phase induction motor where single phase supply is needed to operate it. The speed control of induction motor is done at the cost of decrease in efficiency and low electrical power factor. At the end of the lecture, student should be able to. A 3 phase induction motor is a machine which is constructed to work on the 3 phase supply. Equivalent circuit of induction motor for 3 phase and. The most common type of three phase induction motor is the squirrel cage type. For better understanding the working principle of three phase induction motor let us look into the construction of three phase induction motor. The threephase induction motor is the extensively used for various kinds of industrial drives.
The torque developed by an induction motor is proportional to the slip. A portion of rotating magnetic field in a three phase. As i previously mentioned in my article on introduction to induction motors, there are two main types of induction motors, single phase induction motor and 3 phase induction motor. After looking at some of the considerations for fullvoltage starting, we will consider several. The stators rotating magnetic field cuts rotor conductors which induces voltage and current. Circuit diagram of soft starter for three phase induction motor. Induction motors are most commonly run on single phase or three phase power, but two phase motors exist. Induction motor, working with ac supply, consisting of a rotating magnetic field and stationary rotor find about two types single phase and three phase. Lecture 6 three phase induction motors cairo university. There are mainly two types of induction motor on the basis of power supply, single phase induction motor and three phase induction motor. And the induction motor, especially the three phase induction motor, has two types of equivalent circuits which are. These are the main parts you can check full details about all parts of motors here parts of a motor. The electric motor has its name derived from the fact that the rotor assemble resembles the wheel of a squirrels cage.
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