As the current passes through the coils on opposite sides of the stator, a twopole electromagnet is established, creating a twopole motor. 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. The working of the threephase induction motor is based on the principle of electromagnetic induction. The induction motor is started by itself that we know. An induction motor which connects with a 3 phase supply called 3 phase induction motor. 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.
The 3 phase induction motor is popular for its efficiency and is widely employed in the electric systems for doing mechanical work. You should also make a dc measurement of stator winding linetoline resistance. 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. Explain starting methods of 3 phase induction motor. The basic idea of an electric motor is to generate two magnetic fields.
So, get lets started with the introduction to three phase induction motor. So initially motor starts slowly and then reaches its full rated speed gradually. When the 3 phase supply is provided to the stator, a magnetic field is produced which rotates the rotor and motor. Induction motor 1 chapter 3 induction motor bee23 electrical machine power system 2 learning outcomes. Induction motor basics, single phase and three phase induction. Three phase induction motors are the workhorse of industry. They run at a constant speed from noload to the full load. The speed control of induction motor is done at the cost of decrease in efficiency and low electrical power factor. How a 3 phase ac induction motor works keb keb america.
Induction motor working principle single phase and three. 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. Today, i am gonna give you an introduction of a single phase induction motor. 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. 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. Induction motors are generally two types as we see in the previous article.
An induction motor or asynchronous motor is an ac electric motor in which the electric current. 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. Circuit diagram of soft starter for three phase induction motor. In our industries and household, 3 phase induction motors are used. Three phase induction motors draw six or more times rated current when started at rated voltage. Circuit diagram of smoother start for three phase induction motor using pic microcontroller is shown below. Hi all, let us begin the course on induction motors, in this video, we will have an introduction and basic construction concepts. Three phase ac induction motors are widely used in industrial and commercial applications. And the induction motor, especially the three phase induction motor, has two types of equivalent circuits which are. The electric motor has its name derived from the fact that the rotor assemble resembles the wheel of a squirrels cage. Introduction to induction motor the engineering knowledge. A 3 phase induction motor is a machine which is constructed to work on the 3 phase supply. Difference is that transformer is an alternating flux machine while induction motor is rotating flux machine. Induction motors are most commonly run on single phase or three phase power, but two phase motors exist.
There are two basic reasons for the use of single phase motors rather than 3 phase motors. So the rotor speed will depend on the ac supply and the speed can be controlled by varying the input supply. While materials and insulation systems have changed, the basic principles and operation of an electric. Various regulatory authorities in many countries have introduced and.
The main drawback of dc motors is the presence of commutator and brushes, which require frequent maint. An induction motor can be, squirrel cage induction motor. Introduction to induction motor the engineering projects. Induction motor, working with ac supply, consisting of a rotating magnetic field and stationary rotor find about two types single phase and three phase. For reason of economy, most houses, offices and also rural areas are supplied with single phase a. The 3 phase set of currents, each of equal magnitude and with a phase. At synchronous speed, the slip is zero and hence torque developed by the. The stators rotating magnetic field cuts rotor conductors which induces voltage and current. The most common type of three phase induction motor is the squirrel cage type. All cooling ribs of motors assume vertical or horizontal.
This is how easy it is to implement smooth starter for three phase induction motor. The threephase induction motor is the extensively used for various kinds of industrial drives. 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. The rotor will constantly be turning to align its magnetic field with that of the stator field.
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. Rotating magnetic field in 3 phase induction motor your. This article describes the theory and operation of a three phase ac induction motor. The rotor is separated from the stator by a small airgap which ranges from 0.
The torque developed by an induction motor is proportional to the slip. 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. Understand the principle and the nature of single phase and 3 phase induction machines. At the end of the lecture, student should be able to. An electrical motor is an electromechanical device which converts electrical energy into mechanical energy. Introduction the three phase induction motor is the extensively used for various kinds of industrial drives. It has good speed regulation and high starting torque. An electric motor converts electrical energy into a mechanical energy which is then supplied to different types of loads. 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. China ie2 series threephase asynchronous induction motor. Difference between single phase and three phase induction. Lecture 6 three phase induction motors cairo university. Hi friends, i hope you all are fine and doing great with your lives. 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 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. These motors are selfstarting and use no capacitor, start winding, centrifugal switch or other starting device. Ie2 series three phase asynchronous 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. Ac induction motors are also the most common motors used in main powered home appliances. We also discuss the construction of a three phase motor including its. Parts of an induction motor three phase induction motor. A three phase induction motor is basically a constant speed motor so its somewhat difficult to control its speed.
A portion of rotating magnetic field in a three phase. These types of motors are known as selfstarting induction motors. The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. 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. The first ac commutatorfree threephase induction motors were. One way to reduce the starting current is to start the motor at reduced 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. Assuming that the stator resistance r1 is measured at dc and that phase power. The induction motor has an induction and a resistor which cause losses. Introduction to three phase motors flashcards quizlet. Equivalent circuit of induction motor for 3 phase and. Way more information than you ever wanted on how to fell a tree. Speed control of three phase induction motor electrical4u. Whenever the ac supply is connected to the stator windings, line currents i r, i y, and i b start flowing. Record all nameplate information for the induction motor. A 3 phase induction motor has two main parts i stator and ii rotor. Introduction types of electrical machines types of 3 ph induction motor basic principle working principle compnents of induction motor application comparision between 1ph i.
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. It has been estimated that 70% to 80% of all electricity in the world is consumed by these motors. The 3 phase induction motor has two main components, such as any other motor. Introduction to induction motor instrumentation and control. There are mainly two types of induction motor on the basis of power supply, single phase induction motor and three phase induction motor. In todays post, we will have a look at three phase induction motor construction, working, slip, torque and other parameters. A three phase induction motor runs on a three phase ac supply. Enter the rated volts, amps, power, and efficiency to find the current flowing through the motor.
The stator composes of magnetic strips of magnetic iron. This is the principle of operation of an induction motor of any type. Single phase induction motor the engineering projects. 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. A simple explanation of how a 3 phase induction motor works. 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. Perform an analysis on induction machines which is the most rugged and the most. For better understanding the working principle of three phase induction motor let us look into the construction of three phase induction motor. For information on three phase, you can read my article on 3 phase. Three phase motors are a selfstart and as we studied in a single phase induction motor article it needs capacitors to start its operation.
Watch this video to understand the working principals of the three phase induction motors. Induction motor basics, single phase and three phase. One single phase wattmeter plus miscellaneous apparatus as needed. There are a lot of applications of 3 phase induction motor, to name a few 1. Such high currents may pose serious problems for the motor and the electrical system when large motors are started. The topic lies under the basic electrical and electronics engineering course that. The stator has a three phase stationary winding which can be either star connected or delta connected. Introduction three phase induction motor is the most popular type a.
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