A fan is used to circulate air (or moves air) in a confined area which gives feeling of cooling. It works on the principle of Induction motor. A single phase motor is not a self -starting method hence some special arrangement is required in order to make the motor to start & run. Split phase method single phase motor is used in ceiling fan where capacitor is used for starting & running the motor.
It consists of two windings which are placed 900 electrical apart on the stator of the motor. The main winding is connected directly across the line & the starting winding is connected to the line through a static capacitor of suitable value. The function of capacitor is to provide phase shift(as capacitor in aux winding leads the current in aux winding) with respect to main winding) when single phase ac supply is applied to the motor, two emfs at 900 displaced in time phase are produced in two windings which causes a rotating magnetic field is produced. A capacitor produces high starting torque in the motor.
In ceiling fan motors where motor starts under zero load & low torque is required to operate the motor, a capacitor is permanently connectedin series with auxiliary winding for both starting & running purpose. Therefore, we can say that a permanent capacitor motor is used in ceiling fan motor. That is why when capacitor getsburst, motor doesn’t work as required torque is not produced.
DESIGN, CFM, WATTAGE–
- According to length of fan, ceiling fans areavalablein various sweeps such as 24”, 36”, 42”, 48” & 56” (this is the total diameter of the fan including blades).
- Fans move air when they are switched on & air circulation is measured in CFM (cubic feet per minute) so more CFM means more length of fan.
- A ceiling fan generally produces 120-260 Cum/M or 4237-9181CFM.
- Power consumption is directly proportional to CFM it means more power consumption on more CFM production.
- There is a relation between CFM & Watt (power consumption) which is called Airflow Efficiency i.e CFM/watt.
- Airflow efficiency – 51-150CFM per watt with respect to range of fans from 24”…..56”.
- Ceiling fans are available in 3 blades, 4 blades & 5 blades. As the number of blade increases, the sound level decreases but air circulation decreases however there is no significant increase in air circulation.
(Note– Above parameters are values approximate like CFM, wattage consumption, Air flow varies form company to company & different design.)
STAR RATING OF FANS –
Ceiling fans are available in Energy Star Rating therefore star rated ceiling fans should be bought. Efficiency of the fan increases with increase in star rating, hence 5 star rating fan is more efficient than other low star rating fans. 5 star rating is the highest star rating. Star rating is directly related with wattage consumption of the fan. Highest rating fan will consume less wattage (or power).
PSPO stands for “Peak Speed Performance Output”. PSPO makes it possible to deliver more air over the larger area at the lesser electricity cost. PSPO is the latest air advance technology which improves aerodynamic, principle of electro-mechanics & theory of air displacement. This is achieved through –
- Auto speed retention,
- Double twist angle blades,
- Maxi torque motors,
- Ribbed blade design.
SELECTION OF CEILING FAN –
Selection of ceiling depends on the area which is to be cooled. A reference room size & fan size is give below –
|AREA OF ROOM (in Sqft)||Fan Size|
|Up to 75 sqft||24 – 36”|
|75 to 150 sqft||36”-42”|
|150 to 225 sqft||42”– 48”|
|225 to 400 sqft||48”– 54”|