Concept of ceiling fan working

[Abhi]

Explain rotating magnetic field produced in ceiling fan using combination of phase angle and phase shift due to capacitor with the help of single phase supply. What really happening there?

 

[tom baker]

suggest looking up answer in wikapedia…

 

[LarryFine]

Do you understand how capacitors (and inductors) create a timing shift of current?

Knowing whether you do will help us explain it.

 

[kwired]

The capacitor causes current that is not in phase with the supply current, therefore when applied to an aux winding strategically placed you get areas of the field that reach peak magnetism at different time than the main winding and tend to pull the rotor one direction or the other is about as basic of a description one can make here. This concept is for all single phase induction motors, some use capacitors others use other means to create the phase differential. The capacitor types are the ones that can develop more torque and are what is used for the higher capacity motors, most other methods (there is a "split phase" and "shaded pole" being the majority of other types) are only used on fractional HP motors

 

[rambojoe]

The capacitor causes current that is not in phase with the supply current, therefore when applied to an aux winding strategically placed you get areas of the field that reach peak magnetism at different time than the main winding and tend to pull the rotor one direction or the other is about as basic of a description one can make here. This concept is for all single phase induction motors, some use capacitors others use other means to create the phase differential. The capacitor types are the ones that can develop more torque and are what is used for the higher capacity motors, most other methods (there is a "split phase" and "shaded pole" being the majority of other types) are only used on fractional HP motors

Is this the best you could do?!
Please explain.

 

[kwired]

Is this the best you could do?!
Please explain.

supply current maybe was wrong words to use in there.

main winding has it's own current displacement in relation to the supply voltage based on the inductive reactance of that winding.

Now place aux windings in specific locations relative to to main winding locations around the rotor and use whatever method you wish to create a current in those aux windings that is out of phase with the main winding (capacitor in series with the aux winding is a popular method) and you create peak magnetism that occurs at different timeline in the main and aux winding, which is what creates the so called "rotating magnetic field", though it isn't quite the same rotating field as found in a typical three phase motor it is still effective at getting the rotor to turn.

 

[ggunn]

One thing I know about ceiling fans is that if you slow down a ceiling fan's rotation by mechanical means (like hanging tissue paper "ghosts" on strings from the blades for a kids' Halloween party) you will burn out the motor.

 

[LarryFine]

A capacitor in series with a load will make the current rise earlier during each half of the sine wave. A capacitor-run motor has two sets of windings; one set with a capacitor in series with it, the other set without a capacitor.

The cap makes its windings' magnetic field build up earlier during the A.C. wave than the other set. Placing the two sets in alternating positions around the motor makes the timing difference mimic a rotating magnetic field.

 

[Abhi]

I know I have asked below par question. Capacitor split single phase into two phase with some phase difference. This will produce only pulsating rmf and fan won't move. It is space angle that does the trick which can't understand. Sorry I correct the question...instead of writing space angle I wrote phase angle.

 

[jmellc]

Capacitor gives a swift kick in the butt to start the motor moving. Layman's terms.

 

[GoldDigger]

The rotating magnetic field is the result of the combination of a time (phase) difference between the two windings combined with a spatial (angular) difference between the two windings. Without both there can be no rotating field.

In practice there will not be an exact 90 degree phase difference even though you can easily create a 90 angular displacement. The result is that the strength of the field will vary with rotation angle, but the rotating component is enough to start the motor turning.

Once rotaton has started and reached a critical speed (dependent on the mechanical load), the motor can be powered successfully by a single (run) winding.

 

[Abhi]

The rotating magnetic field is the result of the combination of a time (phase) difference between the two windings combined with a spatial (angular) difference between the two windings. Without both there can be no rotating field.

In practice there will not be an exact 90 degree phase difference even though you can easily create a 90 angular displacement. The result is that the strength of the field will vary with rotation angle, but the rotating component is enough to start the motor turning.

Once rotaton has started and reached a critical speed (dependent on the mechanical load), the motor can be powered successfully by a single (run) winding.

But in ceiling fan no centrifugal switch is present to isolate starting winding.

 

[GoldDigger]

But in ceiling fan no centrifugal switch is present to isolate starting winding.

That is because it is either a permanent split capacitor or a shaded pole motor. A PSC motor would work reasonably well with one winding disconnected, but the current in the two windings is balanced enough (at the expense of starting torque) that there is no reason not to run with both windings energized.
A shaded pole motor produces a rotating magnetic field using two "poles" energized by the same winding, but spatially separated and with a separate partially shorted coil on one pole to produce a phase offset.

 

[Abhi]

That is because it is either a permanent split capacitor or a shaded pole motor. A PSC motor would work reasonably well with one winding disconnected, but the current in the two windings is balanced enough (at the expense of starting torque) that there is no reason not to run with both windings energized.
A shaded pole motor produces a rotating magnetic field using two "poles" energized by the same winding, but spatially separated and with a separate partially shorted coil on one pole to produce a phase offset.

Find the attachment

 

[Abhi]

That is because it is either a permanent split capacitor or a shaded pole motor. A PSC motor would work reasonably well with one winding disconnected, but the current in the two windings is balanced enough (at the expense of starting torque) that there is no reason not to run with both windings energized.
A shaded pole motor produces a rotating magnetic field using two "poles" energized by the same winding, but spatially separated and with a separate partially shorted coil on one pole to produce a phase offset.

A shaded pole motor used in small stand fan and has low torque

 

[Abhi]

I want to know how space angle helps in forming rmf and torque