See that the motor is brought up to speed in normal time. Home category electrical engineering mcq questions and answers 3 phase induction motors 1 the frequency of the induced emf in an induction motor is a. The standard threephase slip ring induction motor in protection class ip 55 has ic 411 cooling. Learn more about the construction and operation of a slip ring induction motor. Slip power recovery system in three phase slip ring induction motor 1jagendra singh, 2swati rani, 3rohini 1 kiit university bhubaneswar, india, electrical department. A 12pole, three phase slip ring induction sacea application 1.
These motors are selfstarting and use no capacitor, start winding, centrifugal switch or other starting device. Feb 20, 2014 the difference between a motor s synchronous speed and its speed at full load. Clean motor thoroughly, blowing out dirt from windings, and wipe commutator and brushes. Makwana and others published three phase slip ring induction motor drive with slip power control analysis for different load torque using microsoft excel as software. You should also make a dc measurement of stator winding linetoline resistance. A 12pole, three phase slip ring induction motor absorbs 250 kw from a. When the 3 phase supply is provided to the stator, a magnetic field is produced which rotates the rotor and motor starts. Applications of threephase induction motors of size varying from half a kilowatt to. The rotor will constantly be turning to align its magnetic field with that of the stator field. The induction motor is started by itself that we know. Methods of speed control of induction motor electrical concepts. If the slip ring induction motor is started with all the slip rings or the rotor terminals.
Pdf this work has developed a steadystate and dynamic mathematical. In an induction motor, torque is equal to the power crossing the air gap divided by the synchronous mechanical speed. A 3 phase 440 v, 50 hz induction motor has 4% slip. In fact, an induction motor can be treated as a rotating transformer i. In this type of three phase induction motor the rotor is wound for the same number of poles as that of stator but it has less number of slots and has less turns per phase of a heavier conductor. See that exposed shaft is free of oil and grease from bearings. Fullload slip varies from less than 1 % in high hp motors to more than 56 % in minor hp motors. Slip ring induction motor fundamentals pnpntransistor. This type of motor has a major use in the different industrial applications due to numerous benefits such as higher efficiency, reliable cost, minimum maintenance and selfstarting feature. Slip ring motors are the motors of choice whenever high starting torque or low starting current are required. Also note such parts as fan cover, ventilation box, bracket, slip ring, etc. C series motors but this disadvantages of the induction motor can be overcome by slip ring induction motor. Feb 25, 2017 depending on type of workload there are various type of starters for a slip ring induction motor. As discussed earlier, a slip ring induction motor is an asynchronous motor, as the rotor never runs in synchronous speed with the stator poles.
Percent slip is a way to measure the speed performance of an induction motor. Also note such parts as fan cover, ventilation box, bracket, slipring, etc. This 3 phase motor is also called as an asynchronous motor. So, this motor is used in applications like lifts, pumps, mills where we require high starting torque.
The basic idea of an electric motor is to generate two magnetic fields. The three phase ac induction motor is a rotating electric machine that is designed to operate on a three phase supply. In this video basic of construction and working principle of 3 phase induction motor is explained with the help of 3d animation. The three phase induction motor is the most widely used electrical motor. When a motor starts to rotate the slip is 100 % and the motor current is at maximum.
The threephase ac induction motor is a rotating electric machine that is designed to operate on a threephase supply. Induction motor basics, single phase and three phase. A wound rotor induction motor is also known as slip ring induction motor. Pdf three phase slip ring induction motor drive with. Slip rings a conductive device attached to the end of a wound rotor that conducts current to the brushes. A wound rotor, has a 3 phase winding similar to the stator winding. Depending on type of workload there are various type of starters for a slip ring induction motor. A 480v, 60 hz, 6pole, threephase, deltaconnected induction motor has the. In three phase induction motor, the power is transferred from stator to rotor.
Slip power recovery system in three phase slip ring induction. Fault identification of 3phase slip ring induction motor by, manivannan. This cooling type corresponds to the design of a surfacecooled motor with a housing featuring cooling fins and an external fan mounted on the shaft. Slip in electrical induction motors engineering toolbox. I will tell about the construction of a wound rotor later in this article. A wound rotor, has a 3phase winding similar to the stator winding. What are the type of starter used for slip ring induction motor. Jun 20, 2015 for a 3 phase slip ring induction motor, the maximum torque is 2.
Fault identification of 3phase slip ring induction motor. The rotor of the slip ring induction motor is also cylindrical or constructed of lamination. Slip ring induction motor application slip ring induction motor provides high starting torque. The slip ring induction motor could be used for industrial wires where variable speed and high starting torque are prime requirements. One singlephase wattmeter plus miscellaneous apparatus as needed. The synchronous speed of the motor is given by equation 1. The induction motor that runs on a three phase ac supply is known as a threephase induction motor. Be specially designed for energy saving purpose which is totally enclosed and fancooled type. Ss 120 x f p 120 x 60 8 900 rpm rotor speed motor slip is known, equation 2. Jun 10, 2017 in this video basic of construction and working principle of 3 phase induction motor is explained with the help of 3d animation.
Bbl manufactures tefc crane duty three phase slip ring motors with type mp. Ball and roller bearings are used to suit heavy duty, torublefree running. Three phase ac induction motors are widely used in industrial and commercial applications. These are of two types, squirrel cage and slip ring motors.
Pdf three phase slip ring induction motor drive with slip power. What is the working principle of slip ring induction motor. Wound rotor induction motor the engineering projects. Starters limit the starting current in an induction motor which goes 56 times of full load current as slip remains 1. 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. Today, i am going to tell you about a wound rotor induction motor, which is also a type of 3 phase induction motor. The difference between a motors synchronous speed and its speed at full load. In twopole singlephase motors, the torque goes to zero at 100% slip zero speed, so these require alterations to the stator such as shadedpoles to provide starting torque. Examine the starter switch, fuses, and other controls. Figure shows the disassembled view of an induction motor with squirrel cage rotor. Standard mp motors are designed for use for s3, s4 or s5 duty with various cyclic duration factors.
There are three basic types of small induction motors. 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 generally humidityprotected motor winding is designed to be in thermal class f and is impregnated using the vpi process. Lecture 6 three phase induction motors cairo university. Due to its continuous torque and vibration free, it is used in hospitals, studio.
Explain starting methods of 3 phase induction motor. They are especially suitable for heavy load inertia applications. The 3phase set of currents, each of equal magnitude and with a phase. In twopole single phase motors, the torque goes to zero at 100% slip zero speed, so these require alterations to the stator such as shadedpoles to provide starting torque. Generally, induction motor provides low starting torque as compared to d. Higher protection classes can be realized on request at any time. Ummu salma ap objective a computer based protection system has been introduced to monitor the various faults of the induction motors and it is achieved with the help of the microcontroller. Induction motor maintenance february 17, 2019 february 24, 2012 by electrical4u maintenance as the name suggests it is the action necessary for retaining or restoring a piece of equipment or machine to the specified operable condition to achieve its maximum useful life. Effects of rotor asymmetry conference paper pdf available june 1997 with 3,019 reads how we measure reads. The slip rings brushes allow external resistors to be connected in series with the winding. Determine the percentage reduction in rotor circuit resistance to get a fullload slip of 3%. Good performance, such as high safety, energy saving, compact design, low noise, little vibration, high torque big breakaway torque, reliable operation, stable running and convenient maintenance. The slip ringsbrushes allow external resistors to be connected in series with the winding. The principle of a 3 phase, two pole stator having three identical windings.
Already since 1927, we are a global manufacturer, supplier, and distributor of large slip ring motors up to 15000 kw and,8 kv. Squirrel cage wound rotor with slip rings the rotating magnetic field. Menzel 3 phase slip ring induction motors in protection class ip 55 are designed in the ic 411 cooling class. Record all nameplate information for the induction motor. Fault identification of 3 phase slip ring induction motor by, manivannan.
Why we need to start induction motor using a starter or with one of starting methods. A 12pole, threephase slipring induction sacea application 1. For a 3phase slipring induction motor, the maximum torque is 2. It consists laminated cylindrical core which has a semiclosed slot at the outer periphery and carries three phase insulated winding. A 12pole, threephase slipring induction motor absorbs 250 kw from a. Squirrel cage motors have a rotor with short circuited bars whereas slip ring. Types, construction and principle of operation, 3 phase induction motor, general. Oct 04, 2017 how motors work for beginners episode 3. But the rotor construction differs with respect to the type of motor. By putting resistance in series with the rotor windings, the starting current can be kept low while mainta. Rotor induction motor an overview sciencedirect topics. One single phase wattmeter plus miscellaneous apparatus as needed. 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.
The rotor winding terminals are connected to three slip rings which turn with the rotor. Nov 27, 2019 the three phase induction motor is the most widely used electrical motor. Compared to squirrel cage rotors, wound rotor motors are. Three phase slip ring induction motor my tech info. The construction of stator of the induction motor is almost the same as other motors.
If the 3phase slip ring induction motor is started as a normal motor with the slip rings shorted, due to low starting torque of slip ring motor, the motor will draw high current i. Three phase slip ring induction motor drive with slip power control analysis for different load torque using microsoft excel as software tool. Oct 10, 2016 today, i am going to tell you about a wound rotor induction motor, which is also a type of 3 phase induction motor. These motors are used for cranes requiring frequent start stops and for speed control. The construction of a stator is the same for both the squirrel cage and slip ring induction motor. Rotor has a winding the same as stator and the end of each phase is connected to a slip ring. Depending upon the type of rotor construction used the three phase induction motor are classified as. The rotor also carries star or delta winding similar to that of stator winding. But at the starting of the induction motor, starting current is very large which may damage motor windings. The motor which employing the wound rotor is known as a slip ring induction motor or phase wound motor. The induction motor that runs on a three phase ac supply is known as a three phase induction motor. Number of poles, frequencies and synchronous induction motor speed. In this way, the slip power of main motor is fed to the. Starting and speed control of 3phase slipring induction.
Slip ring induction motor is made up from wound rotor and squirrel cage induction motor is made up from the squirrel cage rotor. The rotor terminals are connected to three slip rings which turn with the. Construction of three phase induction motor electrical4u. Designing of three phase squirrel cage induction motor for. 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. Stator winding can be either star or delta connected depending upon the design. Induction motor seminar ppt, pdf report study mafia. That is why such motors are known as induction motors. Wound rotor induction motors with three rotor slip rings have been used in adjustable speed drives for many years. Squirrel cage motors have a rotor with short circuited bars whereas slipring motors have wound rotors having three windings each connected in star. The standard three phase slip ring induction motor in protection class ip 55 has ic 411 cooling.
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