Since these are vector equations the line current and power factor may be obtained from them. For this example, refer to the motor equivalent circuit and calculations described above. Torque equation of three phase induction motor electrical4u. If the motor slip is known, the rotor speed can be expressed by the equation. Record all nameplate information for the induction motor. The 3phase set of currents, each of equal magnitude and with a phase. The current in each winding is 120 electrical degrees out of phase with the urrent in the other windings. Following data is taken from no load, locked rotor, and dc tests of a 3phase, wye connected 40 hp, 60 hz, 460 v, induction motor with a. How an induction motor works by equations and physics. The induction motor block implements a three phase induction motor.
The rotor will constantly be turning to align its magnetic field with that of the stator field. With singlephase ac power there is only one single sinusoidal voltage. The reply is to give a start point for your education, on this subject. In this case, power flows from the mechanical system, to the rotor circuit, then across the air gap to the stator circuit and external electrical system.
The induction motor is made up of the stator, or stationary windings, and the rotor. The starting of the motor requires the generation of a rotating magnetic flux similar to the rotating flux in a threephase motor. A 3phase, y connected, 460 volt line to line, 25 horsepower, 60 hz, 8 pole induction motor has the following constants, in ohms per phase referred to the stator. Induction motor formulas with calculations january 11. Rotor the rotor is a rotating part of induction motor. If the threephase induction motor operated on power supply system, the motor can be analyzed by using characteristics of the. The output of the motor drive is 3phase pulse width modulation pwm ranging in possible operation frequencies from 0hz to khz. A 480v, 60 hz, 6pole, threephase, deltaconnected induction motor has the following. The basic idea of an electric motor is to generate two magnetic fields. The threephase induction motor is the extensively used for various kinds of industrial drives. There are three basic types of small induction motors. Calculate i the synchronous speed ii the rotor speed, when slip is 4% and iii. The three phase induction motor is the easiest motor of this type to understand so these notes start with that type.
Pdf design and analysis of three phase induction motor. Three phase ac winding calculation linkedin slideshare. A single phase induction motor requires separate starting circuitry to provide a rotating field to. The relationship to calculate the ss of an induction motor is. Threephase ac winding calculations singlespeed windings kinds of diagrams this calculations program includes all necessary details for rewinding threephase motors. One singlephase wattmeter plus miscellaneous apparatus as needed. The torque produced by three phase induction motor depends upon the following three factors. For the rotor locked, s 1 so that the following equations can be written from the equivalent circuit of. The rotor is connected to the mechanical load through the shaft. Locked rotor test the locked rotor test, like short circuit test on a transformer, provides the information about leakage impedances and rotor resistance.
Arrangement of stator in 3ph induction motor are given below. 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. Three phase induction motor using written pole technology, main winding, exciter winding, control circuit for optimum utilization. The motor drives a mechanical load at a speed of 1170 rpm. Lecture 6 three phase induction motors cairo university. They run at a constant speed from noload to the full load. To this end, it will be assumed that the motor is a balanced three phase wye connected load and that you will therefore need to measure only one lineneutral voltage, only one line current, and only one phase power to characterize p in completely. Introduction induction motors are employed in textile mills, agriculture and almost all the manufacturing industries to drive the loads because of its rugged construction and ease operation.
In the motor name plate the company provide the motor is 15 kw 3 phase induction motor. We will consider a 3phase, y connected machine, the. Most ac power today is produced and distributed as threephase power where three sinusoidal voltages are generated out of phase with each other. Index termscombined stardelta winding, combined wye delta winding. Ss synchronous speed rpm f frequency cycles second 60 p number of poles pole pairs. Find the starting current of 10 hp, three phase 220 v a class motor. Advantages of 3 phase induction motor generally easy to build and cheaper than corresponding dc or synchronous motors induction motor is robust. Theory and analysis of three phase induction motor using. How to calculate the winding calculation of a single phase. 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. Rotor is at the stand still, while low voltage is applied to stator windings to circulate rated current. Single phase motor schematics and working do follow the links as your question is too simple to make a proper re. You will have to carry out the balance exploration yourself.
Perphase equivalent circuit motor slip r 1 and r 2. Synchronous speed, frequency, and poles of the induction motor are related by the formula. The singlephase induction motor is more subtle and less efficient. Induction motor theory quiz electrician practice tests. The single phase induction motor is more subtle and less efficient.
Definition of voltage and current transfer ratio to simplify equations. The magnetic field in the air gap from the voltage applied to the stator. Define the equivalent circuit of the transformer and calculate its efficiency and. Stardelta starting of a three phase induction motor 10. You can then quantify the motor s partload by comparing the measured input power under. The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. Design and analysis of three phase induction motor using computer program. Find the synchronous speed of 4 pole induction motor which operates at 60 hz. The three phase induction motor is the most widely used electrical motor. Ac induction motors are also the most common motors used in main powered home appliances.
The ss is a function of the frequency of the power source and the number of poles pole pairs in the motor. The three phase induction motor is the extensively used for various kinds of industrial drives. The synchronous speed of an induction motor depends on the frequency of the power supply and on the number of poles for which the motor. You should also make a dc measurement of stator winding linetoline resistance. Find the phase of the motor, this will dictate which table you will go to for the flc. Regulation of 3phase alternator by zpf and asa methods 9. It consists stator winding it is housed on the motor frame. The threephase induction motor is the extensively used for various. The threephase induction motor is the easiest motor of this type to understand so these notes start with that type. Single phase induction motor the singlephase motor starting torque is zero because of the pulsating singlephase magnetic flux. Cage induction machines institut fur elektrische energiewandlung. Find the voltage and horsepower of the motor and use the chart to. Wiring methods nec 300 junction and cutout boxes nec 300. To start induction motor by rotor resistance starter 8.
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