All single phase machines have a squirrel cage rotor and its stator winding is single phase with auxiliaries.
Principle:
The single phase machine have squirrel cage rotor. The stator arraignment & auxiliaries are converted in to different classes. The stator winding is single phase, when current is supplied single phase magnetic flux is accordingly produced and links the stationary conductors of rotor which are shorted and as such induce an emf in it, resulting current and magnetic field uniformly. Both the field and rotor flux are in phase, therefore, their is no production of torque.
When field have different angle then mechanical torque is produce and field collide with each other produces rotation. Types of single phase machine are given here,
- Split phase:
There are two windings, the main and auxiliary winding. Some times auxiliary winding has a suitable capacitor in series and centrifugal switch. Both the windings are installed in parallel. when stator is energized two different fields cut each other with different angle cut the rotor conductors, mechanical torque is produce. The centrifugal switch will turn off and main winding takes over the operation. This type of machine is used in all sorts of works.
Shaded pole:
One end of salient each pole is shorted,therefore, in the position of the cycle where current is rising from zero to mid max and falling from zero to mid negative max there will be no flux passes through the shorted portion. Near the positive or negative max the current and its flux is almost constant so maximum flux will touch the rotor conductors.In each cycle this operation will be carried out in all the salient poles which means that the rotor conductors in one cycle shall receive varying magnitude of flux in different conductors around its perifery,therefor, the rotor is exposed to variation in induce emf which will produce varying current and flux thus mechanical torque results.
Univerasal motor:
The stator has salient poles projected and connected to the supply which is in series with rotor circuit.
Rotor has sqiurrel cage construction but conductors are connected to the commutator segment over which carbon brushes are installed. AC supply is installed in series with stator and rotor. This is exactaly a dc series motor and use both on AC and DC and extensively used in different applications.
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