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. If connected to rotor winding the starting torque of motor is equal to the rated torque. Consider an earth fault in the rotor circuit, f as shown in fig. 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 rotor winding terminals are connected to three slip rings which turn with the rotor. This motor is rarely used only 10% industry uses slip ring induction motor. 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. I will tell you about the construction of wound rotor induction motor in the first section. Mechanical design of slip ring motor srsh 2 to 315 m.
A squirrel cage motor is thus preferred to a slip ring motor. Most of the application of industrial as well as domestic are this type of induction motor. It is a type of motor where its external circuit is connected using some. The shortcircuit current of a small 3phase induction motor is 3 times the fullload currents. This paper suggests a novel method of motor starting by inserting a parallel. When running under normal conditions, the slip rings are shortcircuited, using an external metal collar, which is pushed along the shaft to connect the rings. The main difference between slip ring induction motor is in rotor construction and usage. Slip ring induction motor have big advantage of having high starting torque compared to squirrel cage motor. Threephase induction motor singlephase induction motor there are probably more singlephase ac induction motors in use today than the total of all the other types put together.
May 03, 2020 general electric, frame 17, slip ring, rblt, 440 v. The main difference in a slip ring induction motor is on the rotor construction and usage. Its operation is based on the principle that when a current carrying conductor is placed in a. The woundrotor motor is particularly effective in applications where using a. The material pairing used for the slip ring contact system is normally bronzemetal graphite. Efficient variable speed control of slip ring motors can be achieved by converters based upon the slip energy recovery principle first proposed by krammer. The construction of the slipring induction motor is exactly similar to the construction of squirrel cage induction motor.
Number of poles, frequencies and synchronous induction motor speed. Construction of three phase induction motor electrical4u. 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 construction of a stator is the same for both the squirrel cage and slip ring induction motor. There are two types of induction motors, one with wound type rotor, also called slip ring motor and another one with squirrelcage rotor. Slip ring rotor or wound rotor or phase wound rotor. General electric, frame 17, slip ring, rblt, 440 v. The tolerance ring can be assembled coaxially between the drive gear and the output shaft of a small servo motor, so that when the output drives against an obstruction, or receives a shock load, the tolerance ring will permit momentary slip between the gear and the shaft. There is no difference between squirrel cage and slip ring motors. The singlephase ac induction motor best fits this description. Threephase woundrotor induction motor industrial electronics. It is logical that the least expensive, lowest maintenance type motor should be used most often. The brush holders are double boxtype brush holders. General purpose slipring induction motors product catalogue.
In the induction motors used in lift and hoists, you. The construction is simple and robust and it is cheap as compared to slip ring induction motor. Woundrotor motors can be started with low inrush current, by inserting high resistance. What is the working principle of slip ring induction motor.
This motor is called the woundrotor induction motor or slipring ac motor. Depending upon the type of rotor construction used the three phase induction motor are. In normal conditions, the slip ring motor functions like a squirrel cage motor. Squirrel cage rotor wound type rotor or slip ring type rotor squirrel cage rotor in this type rotor as the name suggests it is a rotating part of an electrical machine, in which current is induced by transformer action from rotating magnetic field. So, it is not advised to start a slip ring induction motor with its rotor terminals shorted. The stator is the same as is used with a standard squirrel cage motor.
The phase wound rotor is also called as slip ring rotor. Slip ring induction motor as an extension to the available non slip. A slip ring motor also requires a larger space for the motor and its. This final thesis will mostly be dedicated to induction motors but also to synchronous permanent magnet and reluctance motors. Three phase slip ring induction motor a wound rotor or slip ring motor has a 3phase winding, similar to the stator winding. As it names wound rotor, the rotor is wound with a 3 phase windings.
Slip ring motor 3 with their solid construction and special design in cast iron or steel akh slip ring motors still have a big resonance in numerous industry sectors. Slip ring motor fundamentals bright hub engineering. Using the values of the starting resistors used, actual starting torque can be calculated. Lecture 6 three phase induction motors cairo university. 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. Another type of induction motor was developed for variable speed applications. The slip ringsbrushes allow external resistors to be connected in series with the winding. The slip ring rotor chamber has two modification openings. These are of two types, squirrel cage and slip ring motors.
Oct 10, 2016 a wound rotor induction motor is also known as slip ring induction motor. The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements. Severe arcing between the brushes and collector rings. Saintgobain performance plastics bearings and tolerance rings rencol tolerance rings for micro torque robotics drones. Vibrations amplifications on the unsupported shaft extensions of the rotors. Nov 27, 2019 the construction is complicated and the presence of brushes and slip ring makes the motor more costly. Dec 01, 2017 slipring induction motor also known as rotor resistance start motor.
As there are no brushes and slip ring, these motors requires less maintenance. This means that the state of the carbon brushes and the slip ring rotor can be monitored, and cleaning can take place. When a motor starts to rotate the slip is 100 % and the motor current is at maximum. Slipring induction motor connection and testing youtube. Pdf rotor side control of high power slip ring induction motor. Slip in electrical induction motors engineering toolbox. Starting of slip ring induction motor explained in an easy. By far the most commonly used ac motor is the induction motor. A slip ring motor is expensive, as are its controls, compared to a squirrel cage motor. Slip ring induction motor fundamentals pnpntransistor. Slip ring motors are the motors of choice whenever high starting torque or low starting current are required. What are the applications of a slipring induction motor.
The operating coil of an instantaneous relay is connected on one side to the field circuit through a currentlimiting resistance r and on the other side a small dc power source is connected with polarity as indicated. Already since 1927, we are a global manufacturer, supplier, and distributor of large slip ring motors up to 15000 kw and,8 kv. Slipring induction motor also known as rotor resistance start motor. Dc motors although ac motors are used in most of the cases, dc motors have many applications and used for multipurpose applications. A slip ring in electrical engineering terms is a method of making an electrical connection through a rotating assembly. We develop appropriate solution with characteristic lines that match precisely your specifications and demands for your application. Portland slip ring induction motorsbrush holder problems and. Different construction is done to keeping in view to advance its advantages and applications. Squirrel cage induction motor is used in lathes, drilling machine, fan, blower printing machines etc. A woundrotor motor, also known as slip ring rotor motor, is a type of induction motor where the rotor windings are connected through slip rings to external resistance. By putting resistance in series with the rotor windings, the starting current can be kept low while mainta. The slip ring or wound rotor motor is an induction machine where the rotor comprises a set of coils that are terminated in sliprings to which external impedances can be connected.
The value for k is different for each slip ring motor. Dc motor principle a machine that converts dc power into mechanical energy is known as dc motor. In this article, we shall discuss this motor s construction, working, speed control, advantages, disadvantages, and applications. Fullload slip varies from less than 1 % in high hp motors to more than 56 % in minor hp motors. In the second section, i would be throwing light on the operation and working principle of wound rotor induction motor. Adjusting the resistance allows control of the speedtorque characteristic of the motor. The construction of slip ring induction motor is same as other induction motors. Ysalient features y robust and nonflammable construction. It also requires meticulous and periodic maintenance of the brushes, brush gear, slip rings, external rotor resistances etc. Induction motors have been ruling the industrial world for many decades. Apr 11, 2017 induction motors generally will have low starting torque compared to dc series motor. Larger single phase motors have a second stator winding fed with outofphase current. They are especially suitable for heavy load inertia applications.
Wound rotor induction motor the engineering projects. In the induction motors used in lift and hoists, you will see a type of rotor called a slip ring. Rotor slip ring systems, used with this type of motor, offer a similar service life to that of the d. The basic idea of an electric motor is to generate two magnetic fields. The outer periphery of the rotor has a semiclosed slot which carries a 3 phase insulated windings. It consists of a cylindrical core which is laminated. The rotor will constantly be turning to align its magnetic field with that of the stator field. The slip ring induction motor has two distinctly separate parts, one is the stator and other is the rotor. Clayton electric motor repair, elon college, nc 3365843756 email. Determine the starting torque as a percentage of fullload torque if fullload slip is 3 per cent. Three phase slip ring induction motor my tech info.
The slip ring induction motor is shown in the figure below. Each slip ring motor has a resistance value that when connected to the rotor will result in a starting torque of 100%. Cage induction motor an overview sciencedirect topics. Pdf smooth starting of slip ring induction motors researchgate. Y provides smooth and stepless cutting of resistance in rotor circuit of the motor, reducing starting current and increasing starting torque of slipring induction motor. Slip ring motor conversion to vsd driven standard squirrel. 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%. Formally, it is an electric transmission device that allows energy flow between two electrical rotating parts, such as in a motor.
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