AC Induction Motors (2 Viewers)

[theodore0307]

Can someone please help explain to me how an AC induction motor works.

Thanks.

 

[seventhroot]

simply

> there is a rotor and a stator
> the stator is connected to an AC power supply which produces a changing magnetic field
> the rotor is made up of parallel aluminum bars (that looks like a squirrel cage)
> the AC power creates a changing magnetic field that induces eddy currents which causes it to spin in a way that opposes the motion (lenz's law)

 

[Fizzy_Cyst]

simply

> there is a rotor and a stator
> the stator is connected to an AC power supply which produces a changing magnetic field
> the rotor is made up of parallel aluminum bars (that looks like a squirrel cage)
> the AC power creates a changing magnetic field that induces eddy currents which causes it to spin in a way that opposes the motion (lenz's law)

less simply

> there is a rotor and a stator
> the stator consists of three pairs of opposing coils, each connected to a single phase of a three-phase AC power supply which produces an apparent rotating magnetic field
> the rotor is made up of parallel aluminum bars (that looks like a squirrel cage) connected by an end plate
> the apparent rotating magnetic field produces a change in flux on the squirrel cage, which, according to Faraday's Law induces an EMF, this gives rise to eddy currents which flow through adjacent parallel bars, creating a magnetic field to oppose the change in flux which gave rise to the EMF (Lenz' Law)
> Thus an opposing pole is produced within the rotor bars and this creates a force / torque on the rotor which causes the rotor to spin in the same direction as the apparent rotating magnetic field (i.e., chase the field)

 

[Atef]

So how is the motor effect used in it ?

 

[Fizzy_Cyst]

Motor Effect - current carrying conductor in external magnetic field will experience a force.

Current is induced into the rotor bars due to Faraday/Lenz (rate of change of flux)

It is this induced current, flowing through the rotor bars which causes the rotor bars to experience a force (and hence torque)

So, it is similar to all other motors, just in this case the current is induced rather than supplied by an external power supply.