3 phase squirrel cage induction motor working principle

The stator winding can be either deltaconnected or starconnected. The reason for the name squirrel cage is because of the type of rotor used in these motors. Induction motor works on the principle of electromagnetic induction. The relative motion between this field and the rotation of the rotor induces electric current in the conductive bars. A 3 phase induction motor derives its name from the fact that the rotor current is induced by the magnetic field, instead of electrical connections the operating principle of a 3 phase induction motor is based on the production of r. Three phase squirrel cage induction motors can also be used as generators.

The squirrel cage induction motor has very good speed regulation under varying load conditions. When rotor winding is shortcircuited with no resistance in series, it is called a squirrel cage induction motor and when rotor winding is shorted through a resistance in series, it is. However, the rotor never succeeds in catching up the synchronous speed. Im6 working principle of induction motor concept of slip duration. Almost 90 percentage of induction motors are squirrel cage type, because this type of rotor has the simplest and most rugged construction imaginable and is almost indestructible. Oct 09, 2016 afterwards i will cover the working principle and features of squirrel cage induction motor. The working of the three phase induction motor is based on the principle of electromagnetic induction. Ac induction motors are also the most common motors used in main powered home appliances. The same basic design is used for both single phase and three phase motors over. It is classed as a hightorque, low starting current motor. The rotor is constructed using a number of single bars shortcircuited by end rings and arranged in a hamsterwheel or squirrel cage configuration. We consider a three phase squirrel cage induction motor. Thats why its called squirrel cage induction motor.

Squirrel cage induction motor working principle when a 3 phase supply is given to the stator winding it sets up a rotating magnetic field in space. The majority of commercial and industrial applications usually involve the use of a three phase squirrelcage induction motor. Three phase induction motor construction and working principle. Normally, we use the motors in industrial drives because they are rugged, reliable and economical.

Most of the motors used in industry are induction motors. Also lets get to know the methods which are used to control the speed of squirrel cage. Nowadays, three phase squirrel cage induction motors have been modified such that they can be used in high power servo systems. A threephase power supply provides a rotating magnetic field in an induction motor. The stator winding is connected to the three phase supply terminals. They require little maintenance and are available at very competitive prices. A simple explanation of how a 3 phase induction motor works. Construction of squirrel cage induction motor explained. When a 3 phase supply is given to the stator winding it sets up a rotating magnetic field in space. The working principle of three phase induction motor is basically based on the principle of mutual induction as in case of transformer.

Working principle of 3 phase squirrel cage induction motor. When the 3 phase supply is provided to the stator, a magnetic field is produced which rotates the rotor and motor starts. Due to this flux rotor current induced and rotor flux also generated. Thus the rotor rotates in the same direction as that of stator flux to minimize the relative velocity. Almost 95% of the induction motors used is of squirrel cage type. This rotating magnetic field has a speed which is known as the synchronous speed. The main difference between a standard split phase induction motor and ac motor is that the squirrel cage rotor of a servo motor has made with thinner conducting bars, so that the motor resistance is higher. Most of 3 phase induction motors use squirrel cage rotor as it has a remarkably simple and robust construction enabling it to operate in the most adverse circumstances. Squirrel cage induction motors are simpler in structure than dc motors and are most commonly used in the vsd industry. Though the design of the motor is quite difficult, it has a high starting torque compared to the squirrel type. But the rotor of the induction motor has a short circuited secondary of the transformer.

The parameters of the motor are listed in table 10. Principle of operation the basic difference between an induction motor and a synchronous ac motor is that in the latter a current is supplied onto the rotor. Due to this current, a rotating magnetic field of constant amplitude and a constant speed is. An induction motor or asynchronous motor is an ac electric motor in which the electric current. Start induction motor dynamic and steadystate performance of a capacitorstart single phase induction motor split phase induction. Induction motor working principle single phase and three phase induction motor.

Watch this video and learn basics of squirrel cage induction motor. Therefore, if normal supply voltage is applied to a stationary motor, then similar to a transformer, a very large initial current is taken by the primary, for a short period of time. There are two types of 3 phase induction motor based on the type of rotor used. Jan 28, 2020 for better understanding the working principle of three phase induction motor let us look into the construction of three phase induction motor. The rotor of a three phase squirrel cage induction motor consists of a set of noninsulated bars that are interconnected by shortcircuit rings. Induction motor working principle single phase and three. Aug 02, 2016 the working principle of three phase induction motor is basically based on the principle of mutual induction as in case of transformer. The three phase, squirrelcage induction motor is relatively small in physical size for a given horsepower rating when compared with other types of motors.

The major difference between them is that transformer is static in nature i. However, it suffers from the disadvantage of a low starting torque. This 3 phase motor is also called as an asynchronous motor. Construction of three phase squirrel cage induction motor. Oct 10, 2016 hi friends, i hope you are fine and having fun. An induction motor can be, squirrel cage induction motor. Afterwards i will cover the working principle and features of squirrel cage induction motor. Speed control of three phase squirrel cage induction motor. Nov 27, 2019 thus from the working principle of three phase induction motor, it may be observed that the rotor speed should not reach the synchronous speed produced by the stator. A 3 phase ac current passing through a stator winding produces a rotating magnetic field. Identification of terminals of 3 phase squirrel cage induction motor ee 209 by rajveer singh. An induction motor s rotor can be either wound type or squirrel cage type. It is possible to speed control by regulating rotor resistance. Speed control of three phase squirrel cage induction motor using vf method is implemented.

The working principle of a three phase induction motor is quite simple to understand. Working principle of three phase induction motor electrical. In simple words, the type of 3 phase induction motor which uses a squirrel cage rotor is called squirrel cage induction motor. Threephase squirrelcage induction motors are widely used as industrial drives because they are. The squirrel cage induction motor is the most commonly used motor in industry. Construction of three phase squirrel cage induction motor youtube. The picture of a tiny squirrel cage motor, illustrating the squirrel cage rotor, is shown in figure 3a. Induction motor is used extensively in variously applications from basic domestic appliances to heavy industries. But at the starting of the induction motor, starting current is very large which may damage motor windings. An induction motor can therefore be made without electrical connections to the rotor. Induction motor working principle when a three phase stator winding of an induction motor is connected to the ac supply, current starts flowing in the stator conductors. 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.

Now let us discuss in detail, the most common form of induction motor, the squirrel cage induction motor. In the last sections, i will share some advantages and uses. When a three phase supply is connected to the stator terminals of the squirrel cage motor, the currents in the stator winding give rise to a rotating magnetic field of constant magnitude that induces voltage in the stationary rotor conductors that are shortcircuited and so both circulate currents. If the speeds become equal, there would be no such relative speed, so no emf induced in the rotor, and no current would be flowing, and therefore no torque would be generated. Thus from the working principle of three phase induction motor, it may be observed that the rotor speed should not reach the synchronous speed produced by the stator. Induction motor construction the three phase induction electric motor, as well as any electric motor, consists of two main parts. Induction motor basics, single phase and three phase. The three phase ac induction motor is a rotating electric machine that is designed to operate on three phase supply. This article will explain the principles of squirrel cage motors, how they. This magnetic locking is know as cogging in 3 phase squirrel cage induction motor.

In my last article, we have discussed squirrel cage induction motor which is a type of 3 phase induction motor today, i am going to tell you about a wound rotor induction motor, which is also a type of 3 phase induction motor. A 3 phase squirrel cage induction motor is a type of three phase induction motor which functions based on the principle of electromagnetism. Know how the speed control is easily achieved by changing the number of stator poles. Here, phase a winding starts from the top segment followed by the bottom segment as shown in the figure. Parts of an induction motor three phase induction motor. Before understanding the working of a three phase induction motor, let us look into the necessary constructional details of the engine because the actual working principle of an induction motor lies behind its construction.

It is low cost and requires low maintenance in comparison with. In this article, we will briefly explain working principle of three phase induction motor. If a three phase, squirrelcage induction motor has six poles on the stator winding and is connected to a three phase, 60hertz source, then the synchronous speed of the revolving field is 1,200 rpmrevolutions. Actual starting procedure of 3 phase squirrel cage induction motor,and how to change direction of rotation. In electrical equipment the anchors winding would be induced by the magnetic field, although the rotor takes this part in threephase induction motors. The rotor is separated from the stator by a small airgap which ranges from 0. Threephase induction motor basics instrumentation and. Three phase squirrel cage induction motors are widely used as industrial drives because they are selfstarting, reliable and economical. The rotor is constructed using a number of single bars shortcircuited by end rings and arranged in a hamsterwheel or squirrelcage.

The implementation is done using a rectifier and an inverter, where the pwm triggering pulses were generated by using pic micro controller for switching the igbts of the inverter. The three phase induction motor is the extensively used for various kinds of industrial drives. Squirrel cage induction motor the engineering projects. A 3 phase induction motor has two main parts i stator and ii rotor. A squirrelcage rotor is the rotating part of the common squirrel cage induction motor. Windings are such placed that they are electrically and mechanically 120o apart. The field windings in the stator of an induction motor set up a rotating magnetic field through the rotor. In order to avoid this problem, the rotor slots housing the. Squirrel cage induction motor an overview sciencedirect. 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 n s.

And in the previous article on types of electrical motors, we have classified induction motors based on the type of rotor used. Hi friends, in this article, i am discussing about vfd working principle and hope you will find it very help full and informative. On this topic, i will explain in details about 3 phase induction motor construction before we talked about parts of the electric motor generally but on this topic, we will go deep for 3 phase induction motor construction only. C supply to stator winding flux generated in the stator winding. A hollow rotor would have a much less efficient performance. When rotor winding is shortcircuited with no resistance in series, it is called a squirrel cage induction motor and when rotor winding is shorted through a resistance in series, it is called slip ring induction motor. Once the motor attains the normal speed, the brushes are short circuited, and the wound rotor works as squirrel cage rotor. Because the squirrel cage winding is not large enough to dissipate the heat of continuous operation, large synchronous machines often have protective relays to detect when the machine has fallen out of synchronization with the supply voltage.

A squirrel cage induction motor scim is an asynchronous electric motor, in which the rotor is made with a shortcircuited winding in the form of a squirrel cage. Induction motor might be worked as either motors or generator. Mar 07, 2018 there are two types of rotors which are employed in 3 phase induction motor. This is the basic working principle of induction motor of either type, single phase of 3 phase. Induction motors are generally two types as we see in the previous article. Due to this current, a rotating magnetic field of constant amplitude and a constant speed is set up in the air gap between stator and rotor. What is a squirrel cage motor and how does it work. In order to understand the speed control, theory and methods, it is important that the basic theory of the controlled component i.

An induction motor is an electrical motor whic does not require external excitation of the rotor. Hi friends, in this article, i am going to discuss about induction motor working principle and hoping you will like my effort. The speed of rotating magnetic field is synchronous speed, n s r. The stator has windings that produce a magnetic field, and windings on the rotor cut this field and induce a current in the rotor windings. The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. So as in the previous case, current will be induced in the bars of the squirrel cage.

Explain starting methods of 3 phase induction motor. The rotor consists of a rotor core, a rotor winding and a rotating shaft. Those induction motors which employ squirrel cage rotor are called squirrel cage induction motors. This then creates a magnetic field which, through magnetic interaction, links to the rotating magnetic field in the stator which in turn causes the rotor to turn. Wound rotor induction motor the engineering projects. A simple circuit diagram of the squirrel cage induction motor is shown in the figure. According to a power supply, motors are classified as ac motor and dc motor.

The inputs are the instantaneous voltages at the three terminals. The squirrel cage induction motors are the most common three phase motors used in industrial applications. Three phase induction motor working principle engineering solutions. Advantages of 3 phase induction motor generally easy to build and cheaper than corresponding dc or synchronous motors induction motor is robust.

The majority of commercial and industrial applications usually involve the use of a three phase squirrel cage induction motor. It consists of a cylinder of steel laminations, with aluminum or copper conductors embedded in its surface. Jul 25, 2019 squirrel cage induction motor working principle. Oct 28, 2019 the working principle of a three phase induction motor is quite simple to understand. This article presents an understanding of what squirrel cage induction motors are and how. We saw the working principle of squirrel cage induction motor which is the same in all induction motor. In this example the entire motor winding is represented. Induction motor has the same physical stator as a synchronous machine with an alternate rotor development. A squirrelcage induction motor scim is an asynchronous electric motor. Induction motor working principle your electrical guide. It consists of a laminated cylindrical core having semi closed circular slots at the outer periphery. Designing of three phase squirrel cage induction motor for.

In operation, the nonrotating stator winding is connected to an alternating current power source. These types of motors are known as selfstarting induction motors. An electric motor is an electromechanical device that used to convert electrical energy into mechanical energy. In squirrel cage induction motor, there is a 3 phase winding on the stator slots. A squirrelcage rotor is the rotating part rotor used in the most common form of ac. The induction motor is started by itself that we know. In this work a conventional three phase squirrel cage type induction motor with specifications 10 hp, 415v, stardelta connected and 4 poles is chosen for comparison with our motor, which is designed for good efficiency. Induction motor construction the three phase induction electric motor, as well as any electric motor, consists of two main parts the stator and the rotor. But due to some disadvantages of squirrel cage motor like low starting torque and high phase difference a ringtype is designed. C electrical machine that converts electrical energy into mechanical energy. Thus, principle of 3 phase induction motor also explains why rotor rotates in same direction as the rotating field and why induction motor is self starting. Threephase single switch pwm controlled induction motor.

In the proposed work only one main active switch and six backtoback connected diodes are presents. The threephase induction motor is the extensively used for various kinds of industrial drives. The rotor or stator slot of the induction motor skewed through some angle so that the bars lie under alternate harmonic poles of the same polarity or other words, bars must be skewed through two pitches. Identification of terminals of 3 phase squirrel cage. A wide variety of three phase squirrel cage induction motor options are available to you. Slipring induction motor over squirrel cage induction motor. Motors employing this type of rotor are widely known as phase wound motors or wound motor or slipring motors. How does an electronic soft starter for a 3phase induction motor work. Objectives describe the construction of a threephase, squirrelcage motor, listing the main components of this type of motor. Windings are such placed that they are electrically and mechanically 120 o apart from in space. This rotating magnetic field has a speed which is known as the synchronous speed this rotating magnetic field induces the voltage in rotor bars and hence shortcircuit currents start flowing in the rotor bars. Jul 08, 2017 induction motor working principle when a three phase stator winding of an induction motor is connected to the ac supply, current starts flowing in the stator conductors. When three phase supply is given to the stator winding, a rotating magnetic field of constant magnetic field is produced. I will cover the working principle and features of squirrel cage induction motor.

What characterizes an induction motor is the fact that only the stator is connected to the power supply. The squirrel cage rotor is so called because its construction is reminiscent of the rotating exercise wheel found in some pet cages. It is already discussed in induction motors working principle that the rotor can be assumed as a rotating transformer. The principle of operation of this motor is based on the. A squirrelcage induction motor scim is an asynchronous electric motor, in which. The most common type of rotor used in a three phase induction motor is a squirrel cage rotor. These windings are either star connected or in delta connected.