After a day in the scorching heat, all of us look for a breath of fresh air. Yes, you guessed it right! It’s the fans who come to the rescue. This thing gives us relief from the sultry hot and humid weather. But have you thought what goes on to the making of a fan? Why does it start with the click of a switch? Well, the capacitors are the answer to that question. Capacitors are the powerhouse of electrical charge which empowers the fan to move with one click. Many of us are aware of this feature of capacitors and their utility in operating the ceiling fan. But the catch is all of the fans don’t have them. One of the most well-known examples is the exhaust fan don’t have capacitors in it.Interesting, right?
So the question is why do we have capacitors in a ceiling but not in an exhaust fan? Especially when they also operate by the click of a switch. Let’s implore a little more and get acquainted with their mechanism of action.
The first thing to consider here is the induction motor size. Our regular ceiling fan has a comparatively large motor than the exhaust fan. A large motor requires a greater amount of electric charge to start whereas a small motor requires less charge. Hence, to provide the necessary boost to the motor huge amount of electrical charge needs to be stored in it. This requires the use of the capacitor. Heavier motors like those used in coolers and air conditioners need a larger capacitor. So, using a capacitor in a ceiling fan motor is essential.
The excessive heat generated by exhaust fan is another area of concern. Exhaust fan heats up quickly and liberates a greater amount of heat than ordinary ceiling fans. This excessive heating can damage the capacitors. Thus, the conductors and insulators won’t function properly due to heating. This will further lead to a problem of an inoperative fan. Hence, it is best suited to leave out capacitors from exhaust fans.
Owing to the phase shift and the motor starting requirement, a ceiling fan has two capacitors. A start capacitor to start the large motor and a run capacitor to run the AC motor by changing the magnetic field and turning the phase. Since exhaust fans use a brushless motor, the magnetic field doesn’t need to be changed. Hence, the run capacitor isn’t required for an exhaust fan.
The most definitive reason for not using a capacitor in an exhaust fan is the phase current they use. Ceiling fans like other electrical devices use an induction motor. These induction motors need 2 phase current to run. The capacitor helps in this regard. Ceiling fan employs a split phase capacitor which splits the single phase current into 2 phase. In case of exhaust fans, a brushless motor is employed. This motor can directly use the single phase DC. Hence, capacitors aren’t required for them.
Another vital point is the necessity of torque to rotate the large blades of a ceiling fan. An exhaust fan, on the other hand, has smaller blades which are often symmetric. Hence, it doesn’t require that much torque to start rotating. Now, this torque needed by the large irregular blades of a ceiling fan is provided by the capacitor. The start capacitor provides the necessary force to rotate the blades.
Judging by all the above criteria, it is pretty much clear that ceiling fan and exhaust fan differ significantly in their overall built and mechanism of action. Thus it’s natural they have different requirements which suffice their condition. And if you want some good brands who manufacture quality ceiling fans then you can go for Bajaj, Atomberg, Havells, etc. Shop from the best fans in India to have a cool summer.