the induction motor
as soon as you turn on the power the rotating magnetic field is set up.
the shorted winding in the squirrel cage see this and builds up a temporary magnet
when its up to synchronous speed there is no longer current in the shorted winding in a single pole motor 60hz this speed is 3600 rpm
depending on coupling and skew induction motor is always less than synchronous speed.
the synchronous motor
as soon as you turn on the power the rotating magnetic field is set up
the permanent magnet 0 to 3600 rpm in 1/60th of a second
this requires all the power you can deliver until you reach synchronous speed
a bit hard on the power source
smaller synchronous motors sometimes have a squirrel cage and permanent magnets and enough impedance so they dont put a heavy load on the power
electric clocks have the shorted windings on the poles self starting hi impedance
some older electric clocks didnt have the shorted windings and need to be nudged to get then spinning
The induction motor is the special kind of motor which runs below and above the synchronous speed. which the synchronous motor runs nearly equal the synchronous speed. The operation of synchronous motor runs with dc field excited hence separate dc field current is given to the field circuit. where as the induction motor the field and main field is drawn from the same supply hence no excitation is required. But due to this separate starting mechanism has to be required in case of the single phase induction motor.
When an induction motor is pushed over synchronous speed it will become a generator and will deliver power back to the utility.
A synchronous motor can be a type of 3-Phase AC motor, or not.A synchronous motor is defined by the period of the rotor being synchronized with the frequency of the stator windings' current. The stator windings might be 3-Phase or not (2-Phase would work).Also synchronous motors are not the only type of 3-Phase AC motors. An induction motor could also be 3-Phase AC and has a few advantages and disadvantages over a synchronous motor.
Yes, that is one of the major advantages of a three-phase induction motor.
Split Phase Induction Motor.
The induction motor is the special kind of motor which runs below and above the synchronous speed. which the synchronous motor runs nearly equal the synchronous speed. The operation of synchronous motor runs with dc field excited hence separate dc field current is given to the field circuit. where as the induction motor the field and main field is drawn from the same supply hence no excitation is required. But due to this separate starting mechanism has to be required in case of the single phase induction motor.
Synchronous motors run at synchronous speed. An induction motor that has the same number of poles must run at a sub-synchronous speed to create a second magnetic field (a field that is at a different phase angle) to generate torque.
When an induction motor is pushed over synchronous speed it will become a generator and will deliver power back to the utility.
A synchronous motor can be a type of 3-Phase AC motor, or not.A synchronous motor is defined by the period of the rotor being synchronized with the frequency of the stator windings' current. The stator windings might be 3-Phase or not (2-Phase would work).Also synchronous motors are not the only type of 3-Phase AC motors. An induction motor could also be 3-Phase AC and has a few advantages and disadvantages over a synchronous motor.
Yes, that is one of the major advantages of a three-phase induction motor.
Split Phase Induction Motor.
induction motors have very little starting torque as the motor come up to speed it reduces the torque load until it gets near synchronous speed
by motor starter
Low-power (a few watts) might use a synchronous motor, most fans use an induction motor. Above a couple of horse-power it might be a 3-phase induction motor.
A three-phase motor has a steady rotating magnetic field generated by the stator coil, and the rotor just follows the field.
Three Phase Induction Motor is self starting motor so you can start it by conneting to power lines directly if the power line capacity is sufficient.
For exactly the same reason as three-phase motors always run below synchronous speed. If they were to run at synchronous speed then no voltage and, therefore, no rotor current will be induced into the rotor to drive it.