The magnetization current im flowing in the motors equivalent circuit fig. Three phase squirrel cage induction motors can also be used as generators. An induction motor s rotor can be either wound type or squirrel cage type. Apply rated voltage and frequency with no mechanical load. The curve is nearly linear in normal operating conditions which are between pullout speed and synchronous speed 6. Torquespeed characteristics of three phase squirrel cage.
This paper deals with analysis of high speed squirrel cage induction motor. The induction motors are widely used in the industries and consume maximum power. Nov 18, 2015 induction motor torquespeed characteristics. Also the rotor bars are usually not quite parallel to the rotor shaft but are mounted in a slightly skewed position.
Circuit diagram for noload and blockedrotor test on 3 phase induction motor a. Test motor was tested on bench to experimentally verify the results. Know how the speed control is easily achieved by changing the number of stator poles. Pdf performance analysis of a threephase squirrelcage. Note down the machine ratings and calculate rated current of the machine. It is very commonly used in industries because it is very cheap, robust, efficient, and reliable. Form noload test i 0 is known and f 0 is found out as taking all quantities on per phase values. Equivalent circuit of an induction motor enables the performance characteristics which are evaluated for steady state conditions. The stator winding is assumed to be yconnected with the access to the phase terminals.
Advantages and disadvantages of squirrel cage induction motor. Electric motor wiring 480 volt electrical motor wiring data nema amps, starter size, hmcp size for motors ranging 12 to 500 hp. This motor should be mounted on the motor bench, wherein the motor shaft may be coupled to the dynamometer for taking the measurements. Two digital multimeters and fluke power quality meter with banana cables from the.
Noload and blocked rotor test on an induction machine aim theory. Class b squirrel cage induction motor characterized by normal. Threephase squirrelcage induction motors are widely used as industrial drives because they are selfstarting, reliable and economical. Hp squirrelcage induction motor which you have to parameterize. Typical torquespeed curve of a squirrelcage induction motor given in figure 1 provides information about the operation of induction motor.
Designing of three phase squirrel cage induction motor for. Load test on three phase induction motor theory uncategorized april 15, 2020 0 abdul gofur pdf three phase induction motor tests squirrel cage induction motor load test on three phase induction motor no load test of an induction motor. Class a squirrel cage induction motor characterized by normal starting torque, high starting current, low operating slip, low rotor impedance, good operating characteristics at the expense of high starting current, common applications include fans, blowers, and pumps. Two digital multimeters and fluke power quality meter. Know about the most popular and almost unbreakable construction of squirrel cage induction motor. Instruments connected in the circuit serve the function indicated against each. In first comparison, motor was supplied from laboratory source. Working principle of 3 phase squirrel cage induction motor. To determine the equivalent circuit parameters of an induction motor.
Know about the different winding slots, lamination of the stator and its construction. The speed torque curve of a squirrel cage induction motor and the soft starter, 2892016. Information guide for general purpose industrial ac small. The application of the finite element method for predicting the performance of a threephase squirrel cage induction motor under wide ratio pole. Typical torquespeed curve of a squirrel cage induction motor given in figure 1 provides information about the operation of induction motor. In a threephase induction motor, the rotating magnetic field of the stator passing through the rotor conductors induces a current in the rotor conductors. The squirrel cage induction motor is the most commonly used motor in industry. Pdf improving squirrel cage induction motor efficiency. In order to understand the speed control, theory and methods, it is important that the basic theory of the controlled component i. When a 3 phase supply is given to the stator winding it sets up a rotating magnetic field in space. To obtain the load performance characteristics of a threephase squirrelcage induction motor. Noload and blocked rotor test on an induction machine aim. This paper describes a set of tests carried out on an induction motor for a 75 kw escalator.
Form no load test i 0 is known and f 0 is found out as taking all quantities on per phase values. Also appreciate the rugged construction of squirrel cage rotor and know the spectacular reasons for the skewed arrangements of the rotor conductors. Squirrel cage wound rotor with slip rings the rotating magnetic field the basic idea of an electric motor is to generate two magnetic fields. This rotating magnetic field has a speed which is known as the synchronous speed. To construct the circle diagram three tests are to be performed, namely a no load test. Different method of starting of threephase squirrel cage induction. Slip ring motor is preferred over squirrel cage induction motor where a high starting torque is required b load. To measure the inrush current when the motor starts. If there is no load torque, the load resistance is high and the rotor current is zero. This work is introducing the designing of new three phase squirrel cage induction motor with an objective of getting good efficiency. A 3 phase squirrel cage induction motor is a type of three phase induction motor which functions based on the principle of electromagnetism.
Apr 15, 2020 load test on three phase induction motor theory uncategorized april 15, 2020 0 abdul gofur pdf three phase induction motor tests squirrel cage induction motor load test on three phase induction motor no load test of an induction motor. No load test of induction motor your electrical guide. The motor is rated for horsepower, 208v ll, and 1725 rpm. Induction motor, no load test, blocked rotor test, vibration test. However, for squirrel cage induction machines, the distribution of x. An induction motor is based on the principle of induction of voltages and currents. To conduct the load test on single phase squirrel cage induction motor and to draw the performance characteristics curves. Threephase squirrel cage induction motors are widely used as industrial drives because they are selfstarting, reliable and economical. To construct the circle diagram three tests are to be performed, namely a noload test. Load tests on a threephase induction motor and measurement of the inrush current objectives. Schematic diagram for load test on three phase induction motor. Horizontal squirrel cage mediumvoltage induction motor. A 3 phase ac induction motor photoed by hordu motor.
No load and blocked rotor test on an induction machine. Information guide for general purpose industrial ac small and. Therefore, the motor test operates at same the speed of dynamometer. Load test of induction motor to determine how speed, efficiency, power factor, stator current, torque and slip of an induction motor vary with load, the load test on an induction motor is performed. You should also make a dc measurement of stator winding linetoline resistance using a dmm. If i sc full load current of motor, then p sc is total copper loss on full load. Advantages and disadvantages of squirrel cage induction motor x transformer tap changing working principle electrical machines tap changing in transformers it is a normal fact that increase in load lead to decrease in the supply voltage. Determination of the torquespeed characteristic of induction.
To obtain the load performance characteristics of a threephase squirrel cage induction motor. The major divergence between calculated and measured results are because of input power. An induction motors rotor can be either wound type or squirrelcage type. The stand still rotor resistance and reactance per phase are 0.
They can be used for both star connected or delta connected squirrel cage motors. A three phase, 50 hz, 6 pole squirrel cage induction motor runs at 960 rpm on full load. A blocked rotor test is normally performed on an induction motor to. Diagnostics of rotor and stator problems in industrial induction motors by fang duan b. An induction motor can therefore be made without electrical connections to the rotor. Class b squirrelcage induction motor characterized by normal. Torquespeed characteristics of three phase squirrel cage induction motor aim to obtain the torquespeed characteristics tn r of a three phase squirrel cage induction motor using 1. Blocked rotor test of induction motor electrical4u. A blocked rotor test is normally performed on an induction motor to find out the leakage impedance. To improve its performance characteristics certain tests have been designed like noload test and block rotor test, etc.
Circuit diagram for no load and blockedrotor test on 3 phase induction motor a. The typical constitution of a squirrelcage induction motor, which is composed by three. This rotor is made up from parallel aluminum or copper bars. When load increases in rotor of induction motor how does. The motor was a squirrel cage induction motor, tefv totally enclosed fan ventilated to ip55 rating. Telecommunication engineering, southwest jiaotong university, china, 2005. A typical 3phase squirrelcage motor has six connection leads in the electrical.
Diagnostics of rotor and stator problems in industrial. Electrical motors frame dimensions nema electrical motor frame dimensions. Introduction the squirrelcage induction motor is mounted to the dynamometer. However, should the motor require service, this manual includes a section that assists the. Uses same test instrument setup as lockedrotor test. To draw circle diagram for a three phase induction motor.
Class a squirrelcage induction motor characterized by normal starting torque, high starting current, low operating slip, low rotor impedance, good operating characteristics at the expense of high starting current, common applications include fans, blowers, and pumps. These motors are suitable for all general applications where an open machine is not applicable due to severe environments such as excessive dirt, dust andor moisture. The rotor bars are not insulated from the rotor core because they are made of metals having less resistance than the core. In this test, a rated, balanced ac voltage at a rated frequency is applied to the stator while it is running at no load.
Note down the machine ratings and calculate rated current of the machine noload test. It is basically a three phase step down transformer with different taps provided that permit the user to start the motor at, say, 50%, 65% or 80% of line voltage. For a squirrelcage motor, the rotor as represented in figure 2 is constituted by a system of bars in copper or aluminum, which are coaxial to the rotation axis and directly diecast in the slots made along the external periphery of the ferromagnetic. Construction of squirrel cage induction motor explained. The induced torque of the motor is zero at synchronous speed.
Studying and improving of squirrel cage induction motor scim efficiency is a continuous area of interest not only among the researchers but also the industry, manufacturer and government. Variable voltage variable frequency vf control theory an induction motor compared to a dc motor has some major advantages such as. The no load test is similar to the open circuit test on a transformer. A motor rating of 10 horse power, 415 volts with 1440 rpm and 4pole is selected for design problem and an equivalent circuit model is developed to find out the various. Express the maximum torque developed in terms of full load toque. Record all nameplate information for the induction motor. Jul 25, 2019 squirrel cage induction motor working principle.
Load test on single phase squirrel cage induction motor aim. Teco totally enclosed fan cooled squirrelcage induction motors are designed, manufactured and tested to meet or exceed the latest nema, ieee, csa and other international standards. Note down the machine ratings and calculate rated current of the machine no load test. Also lets get to know the methods which are used to control the speed of squirrel cage. With increased load, the load resistance is less and the current increases. The main difference between slip ring and squirrel cage induction motor is the rotor construction. Gradually apply three phase voltage across motor stator terminals via the autotransformer d.
The speed torque curve of a squirrel cage induction motor and. In this test, the alternator is run with the prime mover i. Dc motors fullload currents full load amps in 120 and 240 volts dc motors. For this to work the motor must see a reactive load, and either be connected to a grid supply or an arrangement of capacitors to provide excitation current. 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.
Introduction the squirrel cage induction motor is mounted to the dynamometer. We saw the construction of the squirrel cage induction motor. It is called a squirrel cage motor because the rotor inside of it known as a squirrel cage rotor looks like a squirrel cage. Disconnect any mechanical load connected to the induction motor. Under both supply conditions, the performance of a 5 hp threephase squirrel cage induction motor was measured through a real load test. The voltage and current is induced in the rotor circuit from the stator circuit for the operation.
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