Hello friends, today I am going to tell you structure and uses of shaded pole induction motors, what is shaded pole induction motor : If you also want to know, then keep reading this article completely.
Structure of Shaded Pole Induction Motor
Structure:- The rotor of this motor is similar to that of a three-wheel cage induction motor. In these, the dissolution is done by induction. An excitation coil is wrapped around the rising pole, but at the same time, it is divided into two parts by making a slot in about 1/3 of the smoke, as in Figure 1. A copper ring is fitted on the small part of the pole, which is called a Shaded coil. This small pole is called the covered pole. An alternating flux is produced when the stator coil is connected to a single-phase supply, as in Fig. 2(a). Because of the covered coil, the flux distribution at each pole is not uniform. This can be understood from Fig. 2(a) and 2(b).
At time t1, the flux in the stator coil rises, and hence the rate of flux change at the pole is high. Due to this flux change, and induced V-carrying force is generated in the holed coil. Since the covered coil is short-circuited, the current starts flowing in it. This current produces a flux, and according to Lange’s law, this flux opposes the flux produced by the stator winding. As a result, the flux in the covered part becomes more minor than in the uncharged part.
- Read more: what is a single-phase transformer
Therefore, the magnetic neutral axis (MNA) position is not in the middle of the pole but on the left side of the pole.
At time t, the current is maximum, and the rate of change in flux is minimum. Therefore the induced V-carrying force in the covered coil is almost zero. Hence, the distribution of flux is uniform at the poles. In this case, the position of (MNA) comes in the middle of the pole.
The current falls at time t, so the flux also decreases. Since there is a change in the flux and induced, V-carrying force is produced in the covered coil. As a result, the flux produced by the covered coil opposes the decrease in the flux of the stator coil. Therefore, the covered part has more flux, and the uncharged part has less flux. In this case, the (MNA) gets displaced in the covered part.
It is clear from the above description that the flux axis gradually shifts from left to right in the time interval t1 to. In a negative semicircle, the flux direction becomes opposite, but (MNA) displacement from left to right is the same as magnetic flux. Due to which the initial torque acts on the motor, and the motor starts rotating.
The starting torque of the covered motor is very low, so this motor is used where the starting torque is required less. The covered ring has IPR loss, so the efficiency of this motor is very low. The low efficiency of very small motors is not objectionable as the total power expenditure in these motors is also very low.
Uses of Shaded Pole Induction Motor
They are commonly used in small fans, cooler pumps, electric clocks, slides and film projectors, air heaters, etc.
what did you learn today:-
Today you learned about the structure and uses of shaded pole induction motors, what is shaded pole induction motor.
- Read more: what is filter circuit?