Need of three phase supply three phase circuits basic. The slip ringsbrushes allow external resistors to be connected in series with the winding. These currents act to produce mmf and ux along the axes of the respective coils. This flux links with the rotor conductors and due to transformer action e. The research was conducted at the laboratory of the electrical engineering of the. The machine designer first assumes the efficiency and power factor at. These types of motors are known as selfstarting induction motors. Circle diagram of an induction motor the circle diagram of an induction motor is very useful to study its performance under all operating conditions. A three phase, 12 pole, salient pole alternator is coupled to a diesel engine running at 500 rpm. Abstract this research is purposed to establish a new method is good and simple to operate the 3phase induction motor on singlephase power by using the capacitors. These motor drives are designed to be used in conjunction with a 3phase induction motor. The torque produced by the 5 th harmonic rotates in the backward direction.
When a three phase supply is given to the three phase stator winding, a rotating magnetic field of constant magnitude is produced as discussed earlier. Introduction types of electrical machines types of 3ph induction motor basic principle working principle compnents of induction motor application comparision between 1ph i. If the frequency of 3phase supply to the stator of 3phase induction motor is increased, then. Working principle of 3phase induction motor electrical. Record all nameplate information for the induction motor. A three phase induction motor runs on a three phase ac supply. Brushless dc motors nyu tandon school of engineering. These igbts are protected against surge voltages using snubber circuit. This circuit 3 phase induction motor starter is one such starter.
Let us consider the space around b0 and ccoil sides. As i mentioned earlier in my article on introduction to induction motors, there are two types of induction motors, single phase induction motor and 3 phase induction motor 3 phase induction motor is the one which operates on three phase ac supply. Air gap length is a major part of induction motor design. Find the starting current of 10 hp, three phase 220 v a class motor. Chapter 3 induction motor and different speed control methods page no 3. This torque produced by fifth harmonic which works as a braking action is small in quantity, so it can be neglected. If the load torque on the motor exceeds this value, the motor will stall, i,e. 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. Frequency of supply to the induction motor f pn120 12. The stator winding carries an alternating current which produces the flux which is also alternating in nature. 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.
If the operating slip of the motor with respect to fundamental component voltage is 0. The 3phase induction motor is connected to 3phase bridge inverter as shown in fig. The rotor winding terminals are connected to three slip rings which turn with the rotor. Video lecture on need of three phase supply of chapter three phase circuits of subject basic electrical engineering for firstyear engineering students. However, recently, it has been increasingly used as variable speed motors driven by an inverter. Difference is that transformer is an alternating flux machine while induction motor is rotating flux machine. His document describes the design road taken when looking at a 3phase variable frequency drive vfd. Fall 2005 ee595s electric drive systems 3 voltsperhertz control history. It is the diagrammatic representation of the performance of the induction motor. The vsi line voltage has a dominant 5 th harmonic component. Home category electrical engineering mcq questions and answers 3 phase induction motors. In a conventional round rotor induction motor the behavior of the machine is only needed to be calculated ov er one pole pi tch. Construction and operating principle of three phase induction machines. You should also make a dc measurement of stator winding linetoline resistance.
Three phase induction motors mcqs with explanatory answers. Reluctance machines, induction machines, synchronous machines, stepper motors, and. This article concentrates only on a threephase induction motor and its protection. It supplies an induction motor ich has a full load speed of 144wh 0 rpm. May 15, 2020 ppt threephase induction motor electrical engineering ee notes edurev is made by best teachers of electrical engineering ee. Lecture 6 three phase induction motors cairo university.
A passive filter at the output of power circuit is used to filter the harmonics. Ppt threephase induction motor electrical engineering. Craig 4 in rotational electromechanical devices other than dc machines, torque is produced as a result of one or more magnetic fields which rotate about the air gap of the device. Pdf construction of three phase linear induction motor. Find the percentage slip and number of poles of the induction motor. Construction and principle of operation of singlephase transformer, emf equation, singlephase autotransformer. One singlephase wattmeter plus miscellaneous apparatus as needed. Design strategy for a 3phase variable frequency drive vfd.
Fall 2005 ee595s electric drive systems 2 overview of strategies voltsperhertz control constant slip control fieldoriented control. It is verylow cost but highly reliable gadget, besides being foolproof. Because these motors typically only have an onoff state of operation, a vfd is needed if multiple operation speeds are desired. 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. A synchronous motor can be a type of 3phase ac motor, or not. Synchronous motors are special types of motors used in constant speed applications, whereas most of the motors used in the industrial applications are of induction type. The major difference between them is that transformer is static in nature i. Design of a three phase squirrel cage induction motor for.
A simple method for operating the threephase induction motor on. 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. The maximum torque is also termed as pullout torque. The power circuit is designed using 25a, 1200v igbt. Matlab simulation for speed control of three phase. Design methodology the design process of induction motor is an iterative process. Induction motors have been traditionally used as constant speed motors supplied by the ac power source. Single phase induction motors electrical engineering info. A synchronous motor is defined by the period of the rotor being synchronized with the frequency of the stator windings current. Threephase or polyphase motors are of mainly two types. Today, i am going to write about 3 phase induction motor. Threephase induction motor protection systems and its. A 3 phase induction motor can be used for different applications with various speed and load requirements. The torque produced by these harmonics rotates in the forward or backward direction at n s 3, n s 5, n s 7 speed respectively.
Circle diagram of an induction motor its construction. Electrical machines electrical engineering ee gate. Of all ac motor available, a poly phase induction motor is one which is most used in several kinds of industrial drives. Speed control of induction motor using pwm technique. The construction of the circle diagram is based on the approximate equivalent circuit shown below. Although single phase induction motor is more simple in construction and is cheaper than a 3phase induction motor of the same frame size, it is less efficient and it operates at lower power factor. Working principle of 3phase induction motor eduction motor works on the principle of electromagnetic induction.
What is common to all the members of this family is that the basic physical process involved in their operation is the conversion of electromagnetic energy. Speed control of three induction motor by vf method for batching motion system. Three phase induction motors mcqs with explanatory answers 1. Crawling and cogging of induction motor electrical4u. This document is highly rated by electrical engineering ee students and has been viewed 2567 times. Here we consider only 5 th and 7 th harmonics and rest are neglected. Microcontroller based control of three phase induction motor using pwm technique. Induction machines guru nanak dev engineering college. A single phase induction motor is inherently not selfstaring can be shown easily. A 3phase 50 hz square wave 6step vsi feeds a 3phase, 4 pole induction motor. Introduction to induction motor the engineering projects. An electrical motor is an electromechanical device which converts electrical energy into mechanical energy.
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