Speed regulation in ceiling fan

Replies

• 

  zaveri

  when capacitors are connected in parallel, then the net the capacitance increases and hence fan speed increases.
  
  but when they are connected in series, the reverse takes place.
• 

  zaveri

  the older larger versions of regulators, which accompany a fan, work by changing the series resistance.
  
  the latest, versions , which are smaller in size, have a zener diode, and you know the rest.
• 

  grsalvi

  zaveri has told correct about speed regulation.But about capacitors,they are meant for starting of 1 phase motor of fan.Nothing to do with speed.
• 

  naveee

  zaveri

  when capacitors are connected in parallel, then the net the capacitance increases and hence fan speed increases.
  
  but when they are connected in series, the reverse takes place.

  plz still ther is confusion...how net capacitance increases the RPm ?? wt is the role of CAPAcitance in single phase induction motor ???
• 

  Ramani Aswath

  zaveri

  the latest, versions , which are smaller in size, have a zener diode, and you know the rest.

  Not a Zener. They have a triac. Speed is controlled by varying the firing angle of the triac so that the applied voltage to the fan changes, therby changing the speed. The zener diode may be used for shifting the firing angle.
• 

  Ramani Aswath

  naveee

  wt is the role of CAPAcitance in single phase induction motor ???

  You need a rotating magnetic field to achieve shaft rotation. The capacitor acts as a phse shifting device. Different capacitance values will achieve different levels of shift. It is possible that the original capacitor was suboptimally wired. The addition made by you might have achieved the best shift thereby causing a speed increase. If you add another capacitor you may over shift and get a lower speed even though the capacitance increased.
• 

  naveee

  bioramani

  Not a Zener. They have a triac. Speed is controlled by varying the firing angle of the triac so that the applied voltage to the fan changes, therby changing the speed. The zener diode may be used for shifting the firing angle.

  firing angle ??? is juss a phase angle or someother thing ????
• 

  naveee

  bioramani

  You need a rotating magnetic field to achieve shaft rotation. The capacitor acts as a phse shifting device. Different capacitance values will achieve different levels of shift. It is possible that the original capacitor was suboptimally wired. The addition made by you might have achieved the best shift thereby causing a speed increase. If you add another capacitor you may over shift and get a lower speed even though the capacitance increased.

  so due to negative phase shift in capacitor ..if capacitor increased ..rotating speed is decreased????
• 

  grsalvi

  naveee

  firing angle ??? is juss a phase angle or someother thing ????

  "The value of phase angle of sinusoidal AC wave at which TRIAC is turned on (i.e. they allow flow of power to fan motor) is called firing angle.
  More is firing angle ,the TRIAC is 'turned on' late ,hence less power reaches the fan and its speed decreases.
  However TRIAC speed control is efficient compared to resistor regulators as there is no heat dissipation involved.
• 

  grsalvi

  Single phase AC motor has two windings : main winding and auxiliary winding.
  Due to single phase supply the winding is able to produce a stationary sinusoidal field(for Rotating you need more than one phase like in 3 phase induction motors which do not need capacitors).
  So to run a single phase motor, Capacitor is added to auxiliary winding.The current in main and auxiliary winding come from same source but due to capacitance in auxiliary winding its current is leading.
  Hence the motor windings has more than one phases.
  This causes stationary field to rotate and turn the shaft .
• 

  naveee

  grsalvi

  "The value of phase angle of sinusoidal AC wave at which TRIAC is turned on (i.e. they allow flow of power to fan motor) is called firing angle.
  More is firing angle ,the TRIAC is 'turned on' late ,hence less power reaches the fan and its speed decreases.
  However TRIAC speed control is efficient compared to resistor regulators as there is no heat dissipation involved.

  wow
• 

  zaveri

  bioramani

  Not a Zener. They have a triac. Speed is controlled by varying the firing angle of the triac so that the applied voltage to the fan changes, therby changing the speed. The zener diode may be used for shifting the firing angle.

  yeah you are right. sorry i spoke too soon
• 

  arunchary

  TRIAC is replacement of inductive (relay) switching to soft switching , and also it as good voltage controlling with respective to currents ,normally we have already developed homeautomation product we used TRIAC to switching and also speed controlling of fan,and it is efficiently working in realtime....
• 

  parin bumia

  thanks..for ur answers...grsalvi...,bioramani sir and zaveri...now i m much clear abt the "speed regulation"..thanks a lot...