By putting resistance in series with the rotor windings, the starting current can be kept low while mainta. Slip ring motors are the motors of choice whenever high starting torque or low starting current are required. We can add external variable resistance to the rotor of this type of motor. The stator separate from rotor by small air gap have ranges from 0. A wound rotor induction motor has a stator like a squirrel cage induction motor, but a rotor with insulated windings brought out via slip rings and brushes. The basic idea of an electric motor is to generate two magnetic fields.
Types, construction and principle of operation, 3 phase induction motor, general phasor diagram, equivalent circuit, power and torque. As its name indicates stator is a stationary part of induction motor. Wound rotor induction motors ac motors electronics. Some changes in the stator may be encountered when a slip ring motor is used in a cascaded system, as the supply for the slave motor is controlled by the. Thus, we modify the construction of the present mechanism by exclusively. Thus we have to control the speed of induction motor using triac voltage controller. The construction of slip ring induction motor is quite different compared to other induction motor. The main difference in a slip ring induction motor is on the rotor construction and usage. A slip ring motor is expensive, as are its controls, compared to a squirrel cage motor.
An ac motor is an electric motor driven by an alternating current ac. Slip in induction motor is the relative speed between the rotating magnetic flux and rotor expressed in terms of per unit synchronous speed. Slip ring induction motor is one of the types of 3phase induction motor and is a wound rotor motor type. Squirrel cage motors are widely used due to their rugged construction and simple design. It is a type of motor where its external circuit is connected using some rings. The rotor of an induction motor can be a squirrel cage rotor or wound. The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. General purpose slipring induction motors cantoni motor pdf.
This article is devoted to slip ring induction motors. The slip ring rotor chamber has two modification openings. There are two types of rotors which are employed in 3 phase induction motor. The rotor winding terminals are connected to three slip rings which turn with the rotor.
The stator of slip ring induction motor is very much the same as that of the squirrel cage induction motor, but the construction of its rotor is very much different. The squirrel cage induction motor is the most popular type of ac motor. Free download induction motor seminar ppt, pdf report. Slip ring motors require external resistors to have high starting torque. Pdf rotor side control of high power slip ring induction motor. A slip ring motor also requires a larger space for the motor and its. Nov 03, 2019 an induction motor also known as an asynchronous motor is a commonly used ac electric motor. Synchronous speed means the speed of the rotating magnetic field in the stator. Split phase induction motor operation and characteristics.
The slipring motor or woundrotor motor is a variation. Three phase slip ring induction motor my tech info. The three phase induction motor is the most widely used electrical motor. In this work a conventional three phase squirrelcage 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. Slip rings induction motor provides some advantages like provides high starting torque, low starting current and it improves the power factor. It also requires meticulous and periodic maintenance of the brushes, brush gear, slip rings, external rotor resistances etc. The difference is that, in the case of the induction motor, the secondary windings can move due to the rotation of the rotor the secondary winding of the im, the induced voltage in it does not have the same frequency of the stator the primary voltage 3192014 emdii induction motor design. As the external resistance is increased from r 1 to r 3 a corresponding reduction in speed is achieved at any particular torque. The motor takes its name from the shape of its rotor windings a ring at either end of the. Rotor induction motor an overview sciencedirect topics. The phase wound rotor is also called as slip ring rotor. Jan 26, 2019 3 phase induction motor winding design with complete explanation follow me on instagram.
Slip ring induction motor working principle electrical mastar. Its operation is based on the principle that when a current carrying conductor is placed in a. This rings attached with high resistance acts as an external circuit for the rotor. A stator winding is placed in the stator of induction motor and the three phase supply is given to it. All motors comply with the following indian and international standards.
If the motor slip is known, the rotor speed can be expressed by the equation. Electrical interview questions which motor is best. Features and benefits the slipring motor is an induction machine where the rotor comprises. Jun 01, 2018 slip in induction motor is the relative speed between the rotating magnetic flux and rotor expressed in terms of per unit synchronous speed.
The slip rings are mounted on the shaft with brushes resting on them. Pdf three phase slip ring induction motor drive with slip power. Before going to the operation and characteristics of splitphase induction motor we should first understand why single phase induction motor is not selfstarting to make a singlephase induction motor selfstarting, we should somehow produce a rotating magnetic field. Some changes in the stator may be encountered when a slip ring motor is used in a cascaded system, as the supply for the slave motor is controlled by the supply. A 3 phase induction motor has two main parts i stator and ii rotor. Induction motors are the most commonly used motors in many applications.
It can improve mechanical performance, simplify system operation and eliminate damageprone wires dangling from movable joints. A slipring motor also requires a larger space for the motor and its. In previous articles i have discussed the construction, operation, starting, speed control, and classes of squirrel cage induction motors. The brushes are connected to the variable resistor. For load sharing to take place automatically, the motor speed should drop considerably as the load increases and this is ensured by using a motor having a high fullload slip, say for example 10%.
The function of the slip rings and the brushes is to provide a means of connecting external resistors in the rotor circuit. The difference of squirrel cage and slip ring induction motor is mainly on torque, speed, slip, resistance and reactance. If the ohmic values of these resistances are properly. Slip ring induction motor construction, working and its. A slip ring can be used in any electromechanical system that requires rotation while transmitting power or signals. We can obtain various type of speed by using microcontroller. It consists of a cylindrical core which is laminated. It consists of a laminated cylindrical core having semi closed circular slots at the outer periphery. This final thesis will mostly be dedicated to induction motors but also to synchronous permanent magnet and reluctance motors. A woundrotor motor, also known as slip ringrotor motor, is a type of induction motor where the rotor windings are connected through slip rings to external resistance. Slip ring induction motors are usually started by connecting starting resistance in the secondary circuit, which are shorted out as the motor speed up.
A slip ring is an electromechanical device that allows the transmission of power and electrical signals from a stationary to a rotating structure. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable. These are also called as asynchronous motors, because an induction motor always runs at a speed lower than synchronous speed. Most of the application of industrial as well as domestic are this type of induction motor.
An induction motor can be defined as the ac electric motor device in which a power source fed by the alternating current with the help of a primary winding. Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed. The most severe type of fault was found to be an opencircuited phase of the load such as may occur in a slip ring motor drive when the brushes bounce. The most basic ways to control the speed of a slip ring induction motor is either from. Induction motor seminar ppt, pdf report study mafia. When loaded, standard motors have between 23% slip, special motors may have up to 7%. There is no difference between squirrel cage and slip ring motors. It is most widely used for industrial applications due to its selfstarting attribute. Starting andcontrol of slipring 5 electrical engineering book. A slipring motor is expensive, as are its controls, compared to a squirrel cage motor. The construction of the slipring induction motor is exactly similar to the construction of squirrel cage induction motor. The slip ringsbrushes allow external resistors to be connected in series with the winding.
General purpose slipring induction motors product catalogue. They are especially suitable for heavy load inertia applications. An operating and maintenance manual, a terminal plan and. Squirrel cage induction motor squirrel cage induction motors are usually used in various industrial applications. Slip ring induction motor are used where high starting torque is required i. Woundrotor motors can be started with low inrush current, by inserting high resistance into the rotor circuit. Slipring induction motor connection and testing youtube. Generally we all are know induction motor is most widely used motor in industrial. For an induction motor with p polesand f frequency, slip for induction motors a very important parameter is the slip of the motor the slip, s, defines the relative speed difference between synchronous speed and rotor speed and is given by.
As discussed earlier, a slip ring induction motor is an asynchronous motor, as the rotor never runs in synchronous speed with the stator poles. Construction of three phase induction motor electrical4u. Rotor side control of high power slip ring induction motor using a. Nov 27, 2019 the three phase induction motor is the most widely used electrical motor. 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. An induction motor also known as an asynchronous motor is a commonly used ac electric motor. Rarely 5% 10% slip ring motors are used in industries because it has several disadvantages like it required. Already since 1927, we are a global manufacturer, supplier, and distributor of large slip ring motors up to 15000 kw and,8 kv. The construction of a stator is the same for both the squirrel cage and slip ring induction motor.
A squirrel cage motor is thus preferred to a slip ring motor. The rotor of the slip ring induction motor is also cylindrical or constructed of lamination. Safe area motors motors for general application cga1d standard squirrel cage tefc motors. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. The 3phase set of currents, each of equal magnitude and with a phase. Slip ring motor fundamentals bright hub engineering. Their sole purpose is to allow resistance to be placed in series with the rotor windings while starting figure below. A wound rotor induction motor has a stator like a squirrel cage induction motor, but a rotor with insulated windings brought out via slip rings and brushes however, no power is applied to the slip rings. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. The rotor is separated from the stator by a small airgap which ranges from 0. The absence of slip ring and brushes make the construction of single phase induction motor very simple and robust. Three phase induction motor construction and working. Stator winding can be either star or delta connected depending upon the design. Slipring induction motor also known as rotor resistance start motor.
Thyristor, slip ring induction motor srim, stator and rotor, polyphase motor, universal. Dec 01, 2017 slipring induction motor also known as rotor resistance start motor. The most severe type of fault was found to be an opencircuited phase of the load such as may occur in a slipring motor drive when the brushes bounce. The rotor of an induction motor can be a squirrel cage rotor or wound type rotor. Adjusting the resistance allows control of the speedtorque characteristic of the motor. Squirrel cage wound rotor with slip rings the rotating magnetic field. Three phase induction motors electric motors bharat bijlee. Almost 80% of the mechanical power used by industries is provided by three phase induction motors because of its simple and rugged construction, low cost, good operating characteristics, the absence of commutator and good speed regulation. Cheap copare to slipring im maintainance is easy cost is less compare to slipring im can use at explosive area starting torque is low compare to slip ring im application. Wound rotor induction motors ac motors electronics textbook. In three phase induction motor, the power is transferred from stator to. So, it is not advised to start a slip ring induction motor with its rotor terminals shorted.
The rotor will constantly be turning to align its magnetic field with that of the stator field. What is the working principle of slip ring induction motor. The slip ring induction motor has two distinctly separate parts, one is the stator and other is the rotor. The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements. Designing of three phase squirrel cage induction motor for. An887, ac induction motor fundamentals microchip technology.
The rotor terminals are connected to three slip rings which turn. Wound rotor induction motors with three rotor slip rings have been used in adjustable speed drives for many years. Starting of slip ring induction motor explained in an easy. In this article, we shall discuss this motor s construction, working, speed control, advantages, disadvantages, and applications.
The outer periphery of the rotor has a semiclosed slot which carries a 3 phase insulated windings. The value of slip in induction motor is can never be zero. This means that the state of the carbon brushes and the slip ring rotor can be monitored, and cleaning can take place. The slip ring rotor chamber of the ic 411 slip ring induction motor is separated by what is known as a labyrinth seal, which prevents contamination from coal dust. This may be achieved by converting a singlephase supply into twophase supply through the use of an additional winding. Slip ring induction motor working principle electrical. Our motors are designed for long life and reliable operation. The slip ring induction motor is shown in the figure below. A squirrel cage motor is thus preferred to a slipring motor. In an induction motor, torque is equal to the power crossing the air gap divided by the synchronous mechanical speed. The slip ring motor has very little application in industries. The rotor circuit resistance has significant impact on starting torque, the speed at which the breakdown torque occurs, and the slip during the normal running operation. An induction motor is an electrical device that converts electrical energy into mechanical energy. It also requires meticulous and periodic maintenance of the brushes, brush gear, sliprings, external rotor resistances etc.
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