· But in case of a single phase induction motor, the stator has two windings instead of one three-phase winding in three phase induction motor. Stator of Single Phase Induction Motor. The stator of the single-phase induction motor has laminated stamping to reduce eddy current losses on its periphery. The slots are provided on its stamping to carry stator or main winding. Stampings are made up of silicon steel to reduce the hysteresis losses. When we apply a single phase AC supply to the stator Estimated Reading Time: 8 mins · In the single-phase induction motor, single-phase a.c supply is given to the stator winding. The stator winding carries an alternating current which produces the flux which is also alternating in nature. This flux is called the main flux. This flux links with the rotor conductors and due to transformer action e.m.f gets induced in the rotor. The induced emf drives current through the rotor as Estimated Reading Time: 10 mins Working principle of single phase induction motor. When the stator of a single phase motor is fed with single phase supply, it produces alternating flux in the stator winding. The alternating current flowing through stator winding causes induced current in the rotor bars (of the squirrel cage rotor) according to Faraday's law of electromagnetic
Shaded Pole Induction Motor Working Principle - your electrical guide
Facebook Twitter. Single phase Induction Motors: Single-phase a. c supply is commonly used f or lighting purpose in shops, offices, houses, schools etc. Hence instead of d. c motors, the motors which work on single-phase a. supply are popularly used, explain the principle of working of a shaded-pole single phase induction motor.
These a. c motors are called single-phase induction motors. A large no. of domestic applications use single-phase induction motors. Here we will learn how does single phase induction motor work.
The power rating of these motors is very small. Some of them are even fractional horsepower motors, which are used in applications like small toys, small fans, hairdryers etc. This article explains the construction, working principle of single-phase induction motors. Similar to a d. c motor, single-phase induction motor also has two main parts, one rotating and other stationary.
The stationary part in single-phase induction motors is Stator and the rotating part is Rotor. The stator has laminated construction, made up of stampings.
The stampings are lotted on its periphery to carry the winding called stator winding or main winding. This is excited by a single-phase a.
c supply. The laminated construction keeps iron losses to the minimum. The stampings are made up of material from silicon steel which minimises the hysteresis loss.
The stator winding is wound for a certain definite number of poles means when excited by single-phase a. c supply, stator produces the magnetic field which creates the effect of the certain definite number of poles. The number of poles for which stator winding is wound explain the principle of working of a shaded-pole single phase induction motor the synchronous speed of the motor.
The synchronous speed is denoted as Ns and it has a fixed relation with supply frequency f and number of poles P. The relation is given by.
This textbook " Electrical Machinery by P. Bhimbhra " is the best in industry. Grab it now for very less price. Buy Now. Must Read:. The induction motor never rotates with the synchronous speed but rotates at a speed that is slightly less than the synchronous speed. The rotor construction is of squirrel cage type. This rotor consists of uninsulated copper or aluminium bars, placed in the slots. The bars are permanently shorted at both the ends with the help of conducting rings called end rings.
The entire structure looks like cage hence it is called a squirrel cage rotor. The construction of single-phase induction motors is shown in below figure:. As the bars are permanently shorted to each other, the resistance of the entire rotor is very very small. The air gap between stator and rotor is kept uniform and as small as possible.
The main feature of this rotor is that it automatically adjusts itself for the same the number of poles as that of the stator winding. The schematic diagram of two-pole single phase induction motor is shown in the below figure:.
Working Principle of S ingle Phase Induction Motors: For the motoring action, there must exist two fluxes which interact with each other to produce the torque.
c motors, field winding produces the main flux while d. c supply given to armature is responsible to produce armature flux. The main flux and armature flux interact to produce the torque. In the single-phase induction motorsingle-phase a. c supply is given to the stator winding. The stator winding carries an alternating current which produces the flux which is also alternating in nature.
This flux is called the main flux. This flux links with the rotor conductors and due to transformer action e. f gets induced in the rotor. The induced emf drives current through the rotor as the rotor circuit is the closed circuit. This rotor current produces another flux called rotor flux required for the motoring action. Thus second flux is produced according to the induction principle due to induced e.
f hence the motor is called induction motor. As against this in d. c motor a separate supply is required to the armature to produce armature flux. This is an important difference between d. c motor and an induction motor. Key Point : Another important difference between the two is that the d, explain the principle of working of a shaded-pole single phase induction motor. motors are self-starting while single-phase induction motors are not self-starting.
Let us see why single-phase induction motors are not self-starting with the help of a theory called double-revolving field theory. Double Revolving Field Theory in single-phase induction motors :. According to this theory, any alternating quantity can be resolved into two rotating components which rotate in opposite directions and each having magnitude as half of the maximum magnitude of the alternating quantity. In case of single-phase induction motorsthe stator winding produces an alternating magnetic field having the maximum magnitude of Φ 1m.
According to double-revolving field theor y, consider the two components of the stator flux, each having magnitude half of maximum magnitude of stator flux i. Both these components are rotating in opposite directions at the synchronous speed Ns which is dependent on frequency and stator poles. Let Φ f is forward component rotating in anticlockwise direction while Φ b is the backward component rotating in a clockwise direction.
The resultant of these two components at any instant gives the instantaneous value of the stator flux at that instant. So resultant of these two is the original stator flux. The below figure shows the stator flux and its two components Φ f and Φ b. At the start, both the components are shown the opposite to each other in figure a.
This is nothing but the instantaneous value of stator flux at the start. After 90°, as shown in figure bthe two components are rotated in such a way that both are pointing in the same direction. Hence the resultant Φ R is the algebraic sum of the magnitudes of the two components. Thus continuous rotation of two components gives the original alternating stator flux. Both the components are rotating explain the principle of working of a shaded-pole single phase induction motor hence get cut by the rotor conductors.
Due to the cutting of flux, e. f gets induced in the rotor which circulates the rotor current. The rotor current produces rotor flux. This flux interacts with forwarding component Φ f to produce a torque in one particular direction say anticlockwise direction. While the rotor flux interacts with the backward component Φ b to produce a torque in the clockwise direction.
Explain the principle of working of a shaded-pole single phase induction motor if anticlockwise torque is positive then clockwise torque is negative. At the start, these two torques are equal in magnitude but opposite in direction.
Each torque tries to rotate the rotor in its own direction. Thus net torque experienced by the rotor is zero at the start. And hence the single-phase induction motors are not self-starting. By providing the additional flux, we can make the motor self starting. Some of the self starting single phase induction motors are Capacitor Start Induction MotorShaded pole induction motor, Permanent split capacitor motor. Torque-Speed Characteristics in Single-phase Induction Motors: The two oppositely directed torques and the resultant torque can be shown effectively with the help of torque-speed characteristics.
So single phase induction motors are not self starting. However if the rotor is given an initial rotation in any direction, the resultant average torque increases in the direction in which rotor is initially rotated and the motor starts rotating in that direction.
But in practice, it is not possible to give initial torque to rotor externally hence some modifications are done in the construction of single phase induction motors to make them self starting. Another theory which can also be used to explain why single phase induction motor is not self starting is cross-field theory. Cross Field Theory in single phase induction motors :. Consider a single phase induction motor with standstill rotor as shown in the below figure.
The stator winding is excited by the single phase a.
Shaded Pole Induction Motor
, time: 18:43Shaded Pole Motor : Working, Characterisitcs and Its Applications
· Working of Shaded Pole Motor. In the core, when a single phase is applied an alternating flux is generated. This flux links with the shaded coil in fraction amounts. Then voltage gets induced in the coil due to the variation in the flux linking. Hence, the shaded portion is short-circuited due to which it produces the circulating current in it. In such a way, the direction is opposing the main blogger.comted Reading Time: 6 mins Shaded Pole Induction Motor Working Principle. During the portion OA of the alternating-current cycle, the flux begins to increase and an EMF is induced in the shading coil. This flux induces voltage and hence current in the copper ring, and by Lenz’s law, the direction of current is such that it opposes the flux entering the coil. Hence, in Estimated Reading Time: 2 mins A Single Phase Induction Motor consists of a single phase winding which is mounted on the stator of the motor and a cage winding placed on the rotor. A pulsating magnetic field is produced, when the stator winding of the single-phase induction motor shown below is energised by a single phase blogger.comted Reading Time: 3 mins
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