It also involves its switchgears to control its starting inrush current. The construction of stator of the induction motor is almost the same as other motors. Wound rotor induction motors ac motors electronics. It can improve mechanical performance, simplify system operation and eliminate damageprone wires dangling from movable joints. They are especially suitable for heavy load inertia applications. The magnetic path comprises a set of slotted steel. Portland slip ring induction motorsbrush holder problems. A slip ring can be used in any electromechanical system that requires rotation while transmitting power or signals. Induction motor seminar ppt, pdf report study mafia.
Overhead crane slip ring motor resistance calculation electrical 1 working principle of control transformers hindi video s. The scheme is somewhat analogous to a primitive kramer system, where a dc motor is coupled to the induction motor shaft and is fed by the rectifier slip power through a diode rectifier. Slip power recovery system in three phase slip ring. It also requires meticulous and periodic maintenance of the brushes, brush gear, sliprings, external rotor resistances etc. Number of poles, frequencies and synchronous induction motor speed. 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. A 3hp, three phase, 4pole, 400v, 50hz, induction motor runs at 1440rpm. Fullload slip varies from less than 1 % in high hp motors to more than 56 % in minor hp motors. C series motors but this disadvantages of the induction motor can be overcome by slip ring induction motor. What are the applications of a slipring induction motor. Slip ring induction motor slip ring induction motor.
The terminals of the rotor windings of the slipring motors. As its name indicates stator is a stationary part of induction motor. The tendency of the rotor teeth to remain under the stator teeth due to direct magnetic attraction is reduced. The working principles and stator construction of the slip ring induction motor are exactly the same as that of the squirrel cage motor. The output of the motor reduces as the thickness of the ring increases. However, it reduces substantially in a slipring motor due to the high impedance of the rotor circuit. This means that the state of the carbon brushes and the slip ring rotor can be monitored, and cleaning can take place. The slip ringsbrushes allow external resistors to be connected in series with the winding. In this article, we will learn about squirrel cage and slip ring induction motors. The rotor core is made up of steel laminations which have slots to accommodate formed 3single phase windings. An induction motor is based on the principle of induction of voltages and currents. Working when a single phase supply is given to the main winding and running winding, a stator magnetic field is produced. Therefore slip ring induction motors are generally employed where load requires high starting torque or good speed control.
Rarely 5% 10% slip ring motors are used in industries because it has several disadvantages like it required. To overcome this problem, the slip ring induction motor comes into the picture. In this way, the slip power of main motor is fed to the. This article is devoted to slip ring induction motors. Wound rotor induction motor the engineering projects. Ysalient features y robust and nonflammable construction.
Therefore slip ring induction motors are generally e. The frequency of rotor induced emf of 400v, three phase, six pole induction motor is 2hz. Learn more about the construction and operation of a slip ring induction motor. In slip ring induction motors, higher starting torque can be attained by providing an external resistance in the rotor circuits during starting of the slipring induction motor. Generally, induction motor provides low starting torque as compared to d. In the second section, i would be throwing light on the operation and working principle of wound rotor induction motor. The 3phase set of currents, each of equal magnitude and with a phase. A slip ring is an electromechanical device that allows the transmission of power and electrical signals from a stationary to a rotating structure. The slip ring induction motor working in the induction principle. The construction of a stator is the same for both the squirrel cage and slip ring induction motor. Slip ring induction motor have big advantage of having high starting torque compared to squirrel cage motor.
Stator winding can be either star or delta connected depending upon the design. Slip ring motors are the motors of choice whenever high starting torque or low starting current are required. Motor runs smoothly as the magnetic hum is reduced b. 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 three phase induction motor is the most widely used electrical motor. The starting of an induction motor does not relate to simple switching alone. The rotor of the slip ring induction motor is also cylindrical or constructed of lamination. Slip ring induction motor working principle electrical. This type of rotor is provided with a 3phase, doublelayer, distributed winding consisting of coils used in alternators. An induction motors rotor can be either wound type or squirrelcage type.
The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements. A squirrel cage motor is thus preferred to a slipring motor. Slipring induction motor connection and testing youtube. Overhead crane slip ring motor resistance calculation. 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%. Slip in induction motor is the relative speed between the rotating magnetic flux and rotor expressed in terms of per unit synchronous speed. Main motor stator terminal is connected to the supply main and the slip power of main motor is fed to the stator terminals of auxiliary induction motor through slip ring as shown in figure below. The value of slip in induction motor is can never be zero. 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. The slip ring motor has very little application in industries. Industrial bus slip rings custom slip rings fo series fiber optic slip ring. Slip ring induction motor advantages and disadvantages. 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. The slip ring induction motors usually have a phasewound rotor.
Advantages and disadvantages of slip ring induction motor. Slip ring induction motor fundamentals pnpntransistor. A slipring motor also requires a larger space for the motor and its. Wound rotor with slip rings the rotating magnetic field. Equivalent circuit of an induction motor enables the performance characteristics which are evaluated for steady state conditions. Slip ring motor fundamentals bright hub engineering. What is the working principle of slip ring induction motor. Induction motors generally will have low starting torque compared to dc series motor. Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed.
Slip ring induction motor is made up from wound rotor and squirrel cage induction motor is made up from the squirrel cage rotor. Methods of speed control of induction motor electrical. Slip ring induction motor application slip ring induction motor provides high starting torque. The rotor terminals are connected to three slip rings which turn with the. As discussed earlier, a slip ring induction motor is an asynchronous motor, as the rotor never runs in synchronous speed with the stator poles. So, this motor is used in applications like lifts, pumps, mills where we require high starting torque. An induction motor can therefore be made without electrical connections to the rotor. When a motor starts to rotate the slip is 100 % and the motor current is at maximum. The voltage and current is induced in the rotor circuit from the stator circuit for the operation. 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. Production of high starting torque with slip ring induction motor.
A wound rotor, has a 3phase winding similar to the stator winding. Three phase slip ring induction motor my tech info. Starting of slip ring induction motor explained in an easy. The torque developed by an induction motor is proportional to the slip. By putting resistance in series with the rotor windings, the starting current can be kept low while mainta. Figure 4 shows the torquespeed characteristics of slip ring induction motor in modified static kramer drive. But the rotor construction differs with respect to the type of motor.
Except some additional functions takes place in this motor which adds an advantage. Free download induction motor seminar ppt, pdf report. Already since 1927, we are a global manufacturer, supplier, and distributor of large slip ring motors up to 15000 kw and,8 kv. A stator winding is placed in the stator of induction motor and the three phase supply is given to it. Squirrel cage motors have a rotor with short circuited bars whereas slipring motors have wound rotors having three windings each connected in star. 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. These motors are having the difference in rotor construction. In three phase induction motor, the power is transferred from stator to.
The rotor will constantly be turning to align its magnetic field with that of the stator field. Lecture 6 three phase induction motors cairo university. The squirrel cage induction motor is the most popular type of ac motor. The rotor winding terminals are connected to three slip rings which turn with the rotor. A wound rotor induction motor is also known as slip ring induction motor. The slip ring rotor chamber has two modification openings. An induction motor or asynchronous motor is an ac electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. The basic idea of an electric motor is to generate two magnetic fields. The working of this motor is similar to that of a normal motor.
Induction motor different types of duties in motor construction how induction motor as a rotating transformer how to run three phase motor on single phase power supply induction motor interview question slip ring induction motor srim vs squirrel cage induction motor scim synchronous watt types of encloser employed in induction motor types of insulation class. A slipring motor is expensive, as are its controls, compared to a squirrel cage motor. Y provides smooth and stepless cutting of resistance in rotor circuit of the motor, reducing starting current and. If the motor slip is known, the rotor speed can be expressed by the equation. Construction of three phase induction motor electrical4u. Advantages and disadvantages of squirrel cage induction motor. The slip ring induction motor has two distinctly separate parts, one is the stator and other is the rotor. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable. The slip ring type motor is shown in the figure below. Their sole purpose is to allow resistance to be placed in series with the rotor windings while starting figure below. Slip in electrical induction motors engineering toolbox. When a 3 phase supply is given to the stator winding it sets up a rotating magnetic field in space. This arrangement in slipring induction motors also reduces the high inrush currents during starting of induction motor.
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