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