The table below gives the commonly encountered problems in 3 phase squirrel cage induction motors, cause of problems and what remedy to apply to bring the motor back to production. Relative humidity shall be below 95%rh for totallyenclosed types, and below. Record all nameplate information for the induction motor. Here we are giving you only overview on 3 phases induction motor. To solve this problem, this method will not be applied to the totality of the signal spectrum but only to a bandwidth of specified frequency. Braking of three phase induction motors is required in many industrial applications. T2 three phase induction motor construction encompassing. Troubles with the induction motors are generally divided into two categories. Design of a three phase squirrel cage induction motor for. Chapter 3 induction motor and different speed control methods page no 3. When three phase stator winding of an induction motor is energized from a 3 phase supply, a rotating magnetic field is set up which rotates around the stator at synchronous speed ns.
Applications of three phase induction motors of size varying from half a kilowatt to thousands of kilowatts are numerous. This represents the main winding of the machine and is to be connected to a 3 phase balanced supply. Induction motor seminar ppt, pdf report study mafia. 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. The stator separate from rotor by small air gap have ranges from 0. It supplies an induction motor which has a full load speed of 1440 rpm. Ac induction motors are also the most common motors used in main powered home appliances. A threephase induction motor problem enginuity systems. Slots are pressed out on the internal periphery of the stator laminations. 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. It is required to reduce the speed of the motor to rpm by inserting resistances in the rotor circuit. A portion of rotating magnetic field in a three phase.
The shaft output of a three phase 60 hz induction motor is 80 kw. This troubleshooting guide can also be applied to other types of three phase induction motors. The machine designer first assumes the efficiency and power factor at the rated condition. A 2pole, 3phase induction motor delivers 37 hp at the shaft at a speed of 2850. Resistance tests on resistance temperature detector rtd circuits. To draw circle diagram for a three phase induction motor. You should also make a dc measurement of stator winding linetoline resistance using a dmm.
We need to give double excitation to make a dc motor to rotate. One singlephase wattmeter plus miscellaneous apparatus as needed. Solve phase a independent of the other phases total system power s 3 v i if desired, phase b and c values can be determined by inspection i. Advantages of 3 phase induction motor generally easy to build and cheaper than corresponding dc or synchronous motors induction motor is robust. Starting of induction motor for induction motors, the starting torque lrt is approximately proportional to the square of the starting current lra drawn from the line. This paper introduces braking of three phase induction motors using. Find the percentage slip and number of poles of the induction motor. In the case of three phase ac alternating current operation, the most widely used motor is a 3 phase induction motor, as this type of motor does not require an additional starting device.
Lecture 6 three phase induction motors cairo university. Testing and inspection of surge protection devices. A 3 phase, 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. The method achieved low starting current by first connecting the stator winding in star configuration, and then after the motor reaches a certain speed, throw switch changes the winding arrangements from star to delta configuration.
A 3 phase, 460v, 60hz, 4pole y connected induction motor has the following equivalent parameters the noload loss, which is pno load,60 w. To construct the circle diagram three tests are to be performed, namely a noload test. In a 3 phase ac induction motor, there are three stator windings, each usually in two halves, with the rotor winding shortcircuited by end rings. They run at a constant speed from noload to the full load. Compare the rotation of this motor with that in figure 164. An electrical motor is an electromechanical device which converts electrical energy into mechanical energy.
Problem 1 the perphase parameters of the equivalent circuit, for a 400v, 60hz, 3 phases, y connected, 4 pole induction motor. This article presents a basic explanation of electric motor construction and. Induction motor problems and solutions pdf 3 phase induction motor pdf three phase induction motor the wound rotor induction motor speed control of induction motor three phase induction motor diagram blocked circle diagram of an induction motor speed control of induction motor by vf method single phase induction motor pdf free download speed control of three phase induction motor. A three phase, 50 hz, 4 pole slip ring induction motor has a star connected rotor. In order to get a full load slip of 5%, calculate the percentage reduction in rotor circuit resistance neglect stator impedance. There are lots of motors and conveyors used in industries for different purposes in some cases motors or conveyors need forward and reverse operation for some control purpose. Maintenance and troubleshooting three phase induction motor. Three phase armature winding is assembled in these holes. Pdf three phase induction motor incipient rotors faults detection. The open circuit voltage on open circuit between the slip rings 0. For this example, refer to the motor equivalent circuit and calculations described above. The most popular type is the 3 phase, squirrelcage ac induction motor.
Generally, it is known as the asynchronous motor because its running speed is less than its synchronous speed. Choose editselectobjectby clicking, and then select the object groups phb and phreb. Torque equation of a three phase induction motor duration. Ansoft rmxprt application note a threephase induction motor problem. These types of motors are known as selfstarting induction motors. An induction motor also known as an asynchronous motor is a commonly used ac electric motor. A three phase, 12 pole, salient pole alternator is coupled to a diesel engine running at 500 rpm. A 480v, 60 hz, 6pole, threephase, deltaconnected induction motor has the. The most common type of ac motor being used throughout the work today is the induction motor. Figure2 shows the connection of a 3phase induction motor with a star delta starter. Before troubleshooting the 3 phase induction motor, we must have to know about the 3 phase induction motor, star delta starter and its connection diagram. There are single phase induction motors and three phase induction motors. Form noload test i 0 is known and f 0 is found out as taking all quantities on per phase values.
One is the electrical faults, such as the various faults of switches, buttons, fuses, electric brushes, stator winding, rotor, starting equipment and so on. Free download induction motor seminar ppt, pdf report. The three phase induction motors are simple in construction, rugged, low cost and easy to maintain. You should also make a dc measurement of stator winding linetoline resistance. The rotor resistance and stand still reactance per phase are 0. As the current passes through the coils on opposite sides of the stator, a twopole electromagnet is established, creating a twopole motor. Use the approximate equivalent circuit a determine the synchronous speed a c determine the input current. An induction motor can be defined as the ac electric motor device in which a power source fed by the alternating current with the help of a primary winding. One single phase wattmeter plus miscellaneous apparatus as needed.
For a 3 phase induction motor, maximum torque is twice the fullload torque and starting torque is 1. A 3 phase induction motor can be used for different applications with various speed and load requirements. The three phase induction motor is the extensively used for various kinds of industrial drives. Vibration testing of motor after it has started running. Air gap length is a major part of induction motor design. Slip method 10 comment on estimation of efficiency of 3 phase induction motor at field. The 3phase set of currents, each of equal magnitude and with a phase difference of 120 o, flow in the stator windings and generate a rotating field will constant magnitude. They are found everywhere from a small workshop to a large manufacturing industry. Induction motor solved problems examples, torque, starting torque, power developed. Necessity of starter function of starter methods of starting 3. Single phase induction motors arenot a selfstarting motor, and three phase induction motor are a selfstarting motor. Solved problems on armature of a dc machine continuation of chapter 2vk.
1279 547 1377 377 878 622 387 480 299 80 1035 597 1344 435 613 428 537 171 683 536 1516 648 1367 1255 126 741 857 1425 138 308 1373 957 1155 539 146 974 611 855