Problems and premature failures often indicate input power system troubles, poor or deteriorating mechanical installations, or malfunctions in the driven machinery. Electrical input voltagethe voltage at which the motor is designed to operate. The induction motor essentially consists of two parts. This maximum torque in an induction motor is called pullout torque or breakdown torque. In common for induction machines is that the stator is made up of a stack of steel laminations pressed into a aluminum or cast iron frame, and. Induction motor theory quiz electrician practice tests. Induction motors a stolp 12610 threephase f electrical frequency the magnetic flux inside the motor rotates at the synchronous speed. The rotor will constantly be turning to align its magnetic field with that of the stator field. The basic idea of an electric motor is to generate two magnetic fields. The motor, used in this thesis work, is a two pole induction machine composed of a cage rotor and a stator containing windings connected to the 3phase power supply. It is logical that the least expensive, lowest maintenance type. As with other electrical machines, an equivalent electric circuit can be developed for the purpose of gaining insight into the motors operation. 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, absence of commutator and good speed regulation.
Three phase induction motors mcqs with explanatory answers 1. Depending on the class and application of the motor, the locked rotor torque can take on values of 0. Massachusetts institute of technology mit opencourseware. A detailed analysis of various methods of starting an ac induction motor and their effects on motor characteristics pdf. Teslas polyphase system and induction motor 125 understand why the motor does not have the highest torque at start, and because of the second mistake he came to the wrong conclusion that that motor can not have the efficiency higher than 0. Induction motor is an ac electric motor, having a stator and a rotor just like other motors, but the working principle is a little different which would be discussed further. Slots on the internal circumference of the stator house the stator winding. It has been more than a century since the principle of the operation of induction motors was discovered. An induction motor or asynchronous motor is a type of alternating current motor where power is supplied to rotor by means of electromagnetic induction. The induction motor is made up of the stator, or stationary windings, and the rotor. The locked rotor test is made at 15 hz to minimize the errors due to saturation and skin effects. Therefore, motor troubleshooting involves the entire system, not just the.
It is logical that the least expensive, lowest maintenance type motor should be used most often. The 3phase set of currents, each of equal magnitude and with a phase. Linear induction motors are quite an engineering marvel, to convert a general motor for a special purpose with more or less similar working principle, thus enhancing its. The motor then produces a constant torque and not a pulsating torque as in other singlephase motors. Motor current monitoring and analysis mcsa is a straight forward tool to diagnosing problems with large inductive motors. The motor is mounted in a test rig that allows one to control the torque applied to the motor shaft and to measure both rpm and torque. Induction motors ppt transformer electrical engineering.
Three phase induction motors mcqs with explanatory answers. In an induction motor, the electric current in the rotor needed to produce torque is obtained via electromagnetic induction from the rotating magnetic field of the stator winding. The perphase equivalent circuit of an induction motor is shown in figure 1. Department of electrical engineering dit, university, dehradun, uttarakhand references. List and describe the more commonly used equipment in an electric substation. 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 to mechanical energy, and vice versa. A rotor also composed of punched laminations, with rotor slots for the rotor winding. An electrical motor is a device that has brought about one of the biggest advancements in the fields of engineering and technology ever since the invention. If the frequency of 3phase supply to the stator of 3phase induction motor is increased, then. Slip ring motor is preferred over squirrel cage induction motor where a high starting torque is required b load. An electric motor rotates because of magnetic force exerted between a stationary electromagnet called the stator and rotating electromagnet called the rotor. Free online electrician practice test questions on induction motor theory quiz leave a reply cancel reply. A stator consisting of a steel frame that supports a hollow, cylindrical core of stacked laminations. There are two types of induction motors, one is named as single phase induction motor, while the second one is named as 3 phase induction motor.
It supplies an induction motor ich has a full load speed of 144wh 0 rpm. Massachusetts institute of technology department of electrical engineering and computer science 6. This torque is related to the motor output power and the rotor speed and out. An induction motor also known as an asynchronous motor is a commonly used ac electric motor. Sep 27, 2016 induction motor is an ac electric motor, having a stator and a rotor just like other motors, but the working principle is a little different which would be discussed further. Fall 2005 ee595s electric drive systems 2 overview of strategies. Design of stator stator of an induction motor consists of stator core and stator slots. For most shore facility applications, this is the case. Singlephase induction 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.
You should also make a dc measurement of stator winding linetoline resistance using a dmm. Determine the motor parameters and the total core, friction and windage losses. In many cases, the singlephase motors on board a ship will be wired into the lighting distribution panels. Pdf construction of three phase linear induction motor. The motor then runs as a singlephase induction motor. Introduction to induction motor the engineering projects. In case of specially designed rotor the peripheral speed can be 60 ms. Differentiate between the various types of generating electric power stations. The rotor of an induction motor can be a squirrel cage rotor or wound.
Nov 03, 2019 an induction motor also known as an asynchronous motor is a commonly used ac electric motor. Menu of essential motor data defining the electrical model the program uses the motor data in the motor menu to generate the impedances of the motor. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. The supply is connected to the stator and the rotor received power by induction caused by the stator rotating flux, hence the motor obtains its name induction motor. Extending binary properties to nary properties 12 8. May 31, 2019 a linear induction motor or lim is a special type of induction motor used to achieve rectilinear motion rather than rotational motion as in the case of conventional motors. Analytic design evaluation of induction machines january 12, 2006 c 2005 james l. Its value is at least twice the fullload value when the motor is operated at rated voltage and frequency. Induction machine control and simulation c 2003 james l. Mostafa elshahed objectives learn a brief history of the electrical power systems construction. Analysis and modelling of an induction machine with a. Model number m800006 outline dimension drawing see figure 4 nameplate data 1 see figure 5 rated frequency 50 hz motor location indoor altitude less than meters relative humidity less than 90% ambient temp 40 degrees c max duty type continuous weight approx. Induction motor testing and evaluation summary as energy costs rise, more emphasis is being placed on determining the health of large inductive motors.
The larger the motor power, the more severe this phenomenon. The induction motor stator resembles the stator of a revolving field, three phase alternator. 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. The three phase induction motor is the most widely used electrical motor. Draw the approximate equivalent circuit for the motor lockrotor noload dc test v line 36. Single phase induction motor 1introduction the singlephase induction machine is the most frequently used motor for refrigerators, washing machines, clocks, drills, compressors, pumps, and so forth. Target motor theory 4 3phase ac induction motor vector control motorola 3. Motor speed relationship the synchronous speed of an ac motor is the speed of the rotating magnetic field set up by the stator winding synchronous speed rpm 120 x frequency divided by the number of poles.
Find the percentage slip and number of poles of the induction motor. Any mechanical load applied to the motor shaft will introduce a torque on the motor shaft. In general, the induction motor is cheaper and easier to maintain compared to other alternatives. An induction motor can be treated as a rotating transformer i. The lighting distribution panels are the source for singlephase power supply. Induction motor notes free download faadooengineers. The circuit impedances are defined in ohms by the following. The first industrial motors of this type were constructed at the end of the nineteenth century and soon gained the favor of users who appreciated their raggedness, simplicity and relatively low manufacturing cost compared to dc commutator motors. Percent of rated output % a efficiency % b power factor c slip d current at 230v a 0 10 20 30 40 50 60 70 80 90 100 110 120 40 50. The following information provides a brief definition and some application considerations regarding motor data on the nameplate. Record all nameplate information for the induction motor. A three phase, 12 pole, salient pole alternator is coupled to a diesel engine running at 500 rpm. The stator or the stationary part consists of three phase winding held in place in the slots of a laminated steel core which is enclosed and supported by a cast iron or a steel frame as shown in fig. Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation.
1251 1684 1093 1591 399 329 227 530 253 165 1391 857 294 1595 1018 791 468 1053 1441 824 1598 3 1372 325 613 684 20 227 762 1344 341 402 1328 502 1070 338 554 1009 960 820 65 538 1280 1043