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Induction-Motor

By Ashik
An induction machine is the most simple electrical machine from constructional point of view, in most of the cases. It can be classified into motor and generator. In this post, I want to discuss the characteristic common to both of these. Detailed description of each will be available soon in other posts.

Induction machines work on induction principle, in other words it depends on Faraday's law of induction (i.e. when a conductor moves in a magnetic field, it gets some voltage(induced voltage). this voltage can set up current if construction permits and can set up its own magnetic field.). In this case it should be noted that moving in a magnetic field actually makes the magnetic flux changing to the moving conductor(actually seems to be changing, from the view point of one who is moving), and this changing magnetic field causes voltage and current to be induced on the moving body.

But if the magnetic filed is itself changing in nature, then it can
induce voltage on a stationary conductor. This is the case for induction motor and generator. Motor remains stationary(rotor of the motor), a changing voltage(i.e. magnetic flux) is supplied to the stator and hence the rotor get some induced voltage because it remains stationary in changing magnetic field. This rotor voltage creates rotor current and rotor magnetic field(rotor flux), this rotor flux try to catch stator flux and thus rotor starts to rotate.

The case is not this simple in practice, but it is indeed the principle of rotation in induction machine.





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