Shaded Pole Induction Motors Working and Construction
Types of single phase induction motor (Split phase Capacitor start etc)
- Now for producing this rotating magnetic field, we require two alternating flux, having some phase difference angle between them.
- The alternating current, after reaching the peak starts to decrease rapidly and in turn decreases the main flux.
- The direction of this field is from non shaded part of the pole to the shaded part of the pole.
Save The stator has salient poles. Thus the motor starting torque is more compared with other types of motors. So in all the above methods or say types of induction motors, the additional flux other than main flux should have a certain phase difference with respect to main or stator flux.
This motor uses entirely different technique to start the motor as compared with other motors so far we have discussed now. The skew can be done for obtaining the better starting torque. Here the rate of change of current is low, as it has already reached the peak or it is very close to peak value. This loop is known as the shading coil.
The flux induces in the shaded portion of the motor, i. Now according to Lenz's law the direction of this current in copper band is such that it opposes its own cause i. So we can call this part as the shaded part and other parts of the pole as unshaded part. Split phase motors give poor starting torque due to small phase difference between main and auxiliary currents.
The part which is covered with the copper ring is called the shaded part and which are not covered by the rings are called unshaded part. This shifting flux is like a rotating weak field moving in the direction from the unshaded portion to the shaded portion of the pole. The shaded pole motor may have two or four poles. To optimize the distribution of the magnetic field, windings are distributed in slots around the stator, with the magnetic field having the same number of north and south poles.
So, these motors produce very high starting torque. The various advantages of Shaded pole motors includes. The copper or aluminum rings permanently short the rotor conductors called the end rings.
This non uniform distribution of flux. The stator is a stationary part and it has laminated construction, which is made up of stampings. The induced currents in the rotor windings in turn create magnetic fields in the rotor that react against the stator field. As the load torque increases beyond breakdown torque the motor stalls.
Shaded Pole Induction Motor Working Principle
It has a cage rotor and stator. Since rotation at synchronous speed would result in no induced rotor current, an induction motor always operates slightly slower than synchronous speed. The advantages of shaded pole induction motor are.
The solution to this problem is that if we make the stator flux rotating type, rather than alternating type, which rotates in one particular direction only. Single Phase Induction Motors are widely used in modern days. The construction of the rotor of the single-phase induction motor is similar to the squirrel cage three-phase induction motor. Stator poles are excited with its own exciting coils by taking the supply from a single phase supply. Three-phase squirrel-cage induction motors are widely used as industrial drives because they are self-starting, ulm bekanntschaften reliable and economical.
Now let us discuss why the axis shift occurs when current is passed through the winding and how the shading coil aids in producing the shift. This non uniform distribution of flux causes magnetic axis to shift in the middle of the non shaded part. This main flux also links with the rotor conductors and hence cut the rotor conductors. This current in copper band produces its own flux.
- The distribution of flux through the poles is greatly influenced by the shading coils.
- Journal of the Institution of Electrical Engineers.
- Squirrel cage type rotor is used in shaded pole induction motors.
- Let us discuss the constructional details, diagrams and working of shaded pole motors in detail.
- In this, stator is constructed in a special way to produce moving magnetic field.
- Split phase induction motor.
The resultant of these two fluxes produce rotating magnetic field and hence the starting torque. Low starting torque, low power factor and low efficiency, copper losses are high due to presence of copper band. Absence of centrifugal switch eliminates the possibility of motor failure due to faulty centrifugal switch mechanisms. How is starting torque generated in shaded pole induction motor? The slot is approximately one-third distance from the edge of the pole.
Here in this article, we use the two pole motor for the sake of simplicity. As the speed of the rotor drops below synchronous speed, the rotation rate of the magnetic field in the rotor increases, männer single inducing more current in the windings and creating more torque. It finds applications in fans and blowers in heaters and air conditioners.
Since the capacitor draws a leading current, the use of a capacitor increases the phase angle between the two currents main and auxiliary and hence the starting torque. Capacitor start capacitor run induction motor. The circulating current develops the flux in the ring which opposes the main flux of the motor. Due to this arrangement, singletreff dillingen centrifugal switch is not required.
What Are Motors
This coil is known as shading coil. The part of the pole which has the coil is called the shaded part and the other part of the pole is called unshaded part. From Wikipedia, the free encyclopedia. The disadvantages of shaded pole induction motor are.
At starting, samenspende single tschechien both starting and running capacitors are connected in series with the auxiliary winding. These are small in size and less expensive to manufacture. The resultant of these two components of flux at any instant of time gives the value of instantaneous stator flux at that particular instant. These aluminum or copper bars are called rotor conductors and placed in the slots on the periphery of the rotor. The current carried by stator winding produces alternating flux.
Shaded Pole Induction Motor Working and Application Explained
This current is called the rotor current. This is the key strength of these motors. Alternating flux is produced by input ac supply.