3 phase squirrel cage induction motor working principle

This rotating magnetic field has a speed which is known as the synchronous speed. 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. The major difference between them is that transformer is static in nature i. 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. 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. An induction motor is an electrical motor whic does not require external excitation of the rotor. 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. The squirrel cage induction motors are the most common three phase motors used in industrial applications. Mar 07, 2018 there are two types of rotors which are employed in 3 phase induction motor. 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.

Construction of three phase squirrel cage induction motor youtube. 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. Identification of terminals of 3 phase squirrel cage. Squirrel cage induction motor an overview sciencedirect. Induction motor is used extensively in variously applications from basic domestic appliances to heavy industries. 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. An induction motor can be, squirrel cage induction motor.

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. The picture of a tiny squirrel cage motor, illustrating the squirrel cage rotor, is shown in figure 3a. The parameters of the motor are listed in table 10. 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. Ac induction motors are also the most common motors used in main powered home appliances. It consists of a cylinder of steel laminations, with aluminum or copper conductors embedded in its surface. Induction motor working principle single phase and three. Objectives describe the construction of a threephase, squirrelcage motor, listing the main components of this type of motor. The speed of rotating magnetic field is synchronous speed, n s r. Squirrel cage induction motors are simpler in structure than dc motors and are most commonly used in the vsd industry.

So as in the previous case, current will be induced in the bars of the squirrel cage. Induction motor basics, single phase and three phase. Watch this video and learn basics of squirrel cage induction motor. A simple explanation of how a 3 phase induction motor works. The three phase, squirrelcage induction motor is relatively small in physical size for a given horsepower rating when compared with other types of motors. It consists of a laminated cylindrical core having semi closed circular slots at the outer periphery.

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. The working principle of a three phase induction motor is quite simple to understand. The working of the three phase induction motor is based on the principle of electromagnetic induction. Speed control of three phase squirrel cage induction motor. These types of motors are known as selfstarting induction motors. Induction motor working principle single phase and three phase induction motor. 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. Slipring induction motor over squirrel cage induction motor.

Induction motor works on the principle of electromagnetic induction. Motors employing this type of rotor are widely known as phase wound motors or wound motor or slipring motors. 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. This article will explain the principles of squirrel cage motors, how they. The three phase ac induction motor is a rotating electric machine that is designed to operate on three phase supply. 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.

Due to this flux rotor current induced and rotor flux also generated. Afterwards i will cover the working principle and features of squirrel cage induction motor. Working principle of 3 phase squirrel cage induction 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 n s. Construction of squirrel cage induction motor explained. Windings are such placed that they are electrically and mechanically 120 o apart from in space.

However, the rotor never succeeds in catching up the synchronous speed. The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. Most of the motors used in industry are induction motors. But at the starting of the induction motor, starting current is very large which may damage motor windings. Three phase squirrel cage induction motors are widely used as industrial drives because they are selfstarting, reliable and economical. The threephase induction motor is the extensively used for various kinds of industrial drives. They require little maintenance and are available at very competitive prices. 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. This article presents an understanding of what squirrel cage induction motors are and how. But the rotor of the induction motor has a short circuited secondary of the transformer. A wide variety of three phase squirrel cage induction motor options are available to you.

Nowadays, three phase squirrel cage induction motors have been modified such that they can be used in high power servo systems. The rotor is constructed using a number of single bars shortcircuited by end rings and arranged in a hamsterwheel or squirrelcage. But due to some disadvantages of squirrel cage motor like low starting torque and high phase difference a ringtype is designed. In electrical equipment the anchors winding would be induced by the magnetic field, although the rotor takes this part in threephase induction motors. In order to avoid this problem, the rotor slots housing the. I will cover the working principle and features of squirrel cage induction motor. The rotor is separated from the stator by a small airgap which ranges from 0. 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.

In operation, the nonrotating stator winding is connected to an alternating current power source. A squirrelcage rotor is the rotating part rotor used in the most common form of ac. It is possible to speed control by regulating rotor resistance. The reason for the name squirrel cage is because of the type of rotor used in these motors.

Induction motor might be worked as either motors or generator. Wound rotor induction motor the engineering projects. The majority of commercial and industrial applications usually involve the use of a three phase squirrel cage induction motor. What characterizes an induction motor is the fact that only the stator is connected to the power supply. The inputs are the instantaneous voltages at the three terminals.

In this article, we will briefly explain working principle of three phase induction motor. The induction motor is started by itself that we know. Thats why its called squirrel cage induction motor. An induction motor can therefore be made without electrical connections to the rotor. Hi friends, in this article, i am discussing about vfd working principle and hope you will find it very help full and informative. A squirrelcage induction motor scim is an asynchronous electric motor. 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. The three phase induction motor is the extensively used for various kinds of industrial drives. The majority of commercial and industrial applications usually involve the use of a three phase squirrelcage induction motor.

In the last sections, i will share some advantages and uses. Squirrel cage induction motor the engineering projects. When three phase supply is given to the stator winding, a rotating magnetic field of constant magnetic field is produced. 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. Explain starting methods of 3 phase induction motor.

Working principle of three phase induction motor electrical. 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. In the proposed work only one main active switch and six backtoback connected diodes are presents. The stator winding is connected to the three phase supply terminals. Hi friends, in this article, i am going to discuss about induction motor working principle and hoping you will like my effort. The stator winding can be either deltaconnected or starconnected. 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. A 3 phase squirrel cage induction motor is a type of three phase induction motor which functions based on the principle of electromagnetism. Almost 95% of the induction motors used is of squirrel cage type. Jul 25, 2019 squirrel cage induction motor working principle.

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. 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. A squirrelcage induction motor scim is an asynchronous electric motor, in which. The same basic design is used for both single phase and three phase motors over. However, it suffers from the disadvantage of a low starting torque.

Also lets get to know the methods which are used to control the speed of squirrel cage. In simple words, the type of 3 phase induction motor which uses a squirrel cage rotor is called squirrel cage induction motor. A simple circuit diagram of the squirrel cage induction motor is shown in the figure. When a 3 phase supply is given to the stator winding it sets up a rotating magnetic field in space. When the 3 phase supply is provided to the stator, a magnetic field is produced which rotates the rotor and motor starts. It is low cost and requires low maintenance in comparison with. The rotor of a three phase squirrel cage induction motor consists of a set of noninsulated bars that are interconnected by shortcircuit rings. 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. Oct 10, 2016 hi friends, i hope you are fine and having fun. Three phase induction motor working principle engineering solutions. Induction motor construction the three phase induction electric motor, as well as any electric motor, consists of two main parts. The starting torque of this motor ranges from 200 to 250 percent of fullload torque with a starting current of 4 to 6 times the fullload value.

Start induction motor dynamic and steadystate performance of a capacitorstart single phase induction motor split phase induction. There are two types of 3 phase induction motor based on the type of rotor used. 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. Parts of an induction motor three phase induction motor. This magnetic locking is know as cogging in 3 phase squirrel cage induction motor. And in the previous article on types of electrical motors, we have classified induction motors based on the type of rotor used. The squirrel cage induction motor is the most commonly used motor in industry. A hollow rotor would have a much less efficient performance. 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. 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.

The rotor is constructed using a number of single bars shortcircuited by end rings and arranged in a hamsterwheel or squirrel cage configuration. Due to this current, a rotating magnetic field of constant amplitude and a constant speed is. Know how the speed control is easily achieved by changing the number of stator poles. The principle of operation of this motor is based on the. The working principle of three phase induction motor is basically based on the principle of mutual induction as in case of transformer. Actual starting procedure of 3 phase squirrel cage induction motor,and how to change direction of rotation. According to a power supply, motors are classified as ac motor and dc motor. It is classed as a hightorque, low starting current motor. Induction motors are generally two types as we see in the previous article. An induction motor s rotor can be either wound type or squirrel cage type. Windings are such placed that they are electrically and mechanically 120o apart.

Identification of terminals of 3 phase squirrel cage induction motor ee 209 by rajveer singh. Three phase induction motor construction and working principle. Though the design of the motor is quite difficult, it has a high starting torque compared to the squirrel type. Advantages of 3 phase induction motor generally easy to build and cheaper than corresponding dc or synchronous motors induction motor is robust. A 3 phase ac current passing through a stator winding produces a rotating magnetic field. Construction of three phase squirrel cage induction motor. Once the motor attains the normal speed, the brushes are short circuited, and the wound rotor works as squirrel cage rotor. 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. What is a squirrel cage motor and how does it work. Those induction motors which employ squirrel cage rotor are called squirrel cage induction motors. 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. The squirrel cage rotor is so called because its construction is reminiscent of the rotating exercise wheel found in some pet cages. Threephase squirrelcage induction motors are widely used as industrial drives because they are. Oct 09, 2016 afterwards i will cover the working principle and features of squirrel cage induction motor.

Threephase induction motor basics instrumentation and. Three phase squirrel cage induction motors can also be used as generators. A squirrelcage rotor is the rotating part of the common squirrel cage induction motor. Induction motor working principle your electrical guide. Oct 28, 2019 the working principle of a three phase induction motor is quite simple to understand. Im6 working principle of induction motor concept of slip duration. Threephase single switch pwm controlled induction motor. This 3 phase motor is also called as an asynchronous motor. The squirrel cage induction motor has very good speed regulation under varying load conditions. 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. 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.

In squirrel cage induction motor, there is a 3 phase winding on the stator slots. The most common type of rotor used in a three phase induction motor is a squirrel cage rotor. Designing of three phase squirrel cage induction motor for. 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 field windings in the stator of an induction motor set up a rotating magnetic field through the rotor. Thus the rotor rotates in the same direction as that of stator flux to minimize the relative velocity. 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. C electrical machine that converts electrical energy into mechanical energy. The rotor consists of a rotor core, a rotor winding and a rotating shaft. An electric motor is an electromechanical device that used to convert electrical energy into mechanical energy.

Now let us discuss in detail, the most common form of induction motor, the squirrel cage induction motor. It is already discussed in induction motors working principle that the rotor can be assumed as a rotating transformer. C supply to stator winding flux generated in the stator winding. A threephase power supply provides a rotating magnetic field in an induction motor. How does an electronic soft starter for a 3phase induction motor work. 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. 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. 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. The relative motion between this field and the rotation of the rotor induces electric current in the conductive bars. Induction motor has the same physical stator as a synchronous machine with an alternate rotor development. Here, phase a winding starts from the top segment followed by the bottom segment as shown in the figure. These windings are either star connected or in delta connected.