Fans have single phase induction motor. This motor is not self starting i.e., it requires starting torque to rotate. Simply single phase AC supply is unable to rotate the induction motor. So, by a capacitor we provide one more flux which is in lead by 90° from our AC supply and then we get rotating magnetic field.

Now, due to rotating magnetic field emf is induced in the rotor. And according to Fleming left hand rule, motor starts to rotate.

Ceiling fans in India are different from the ceiling fans used in the US. The major difference can be seen in the total number of blades. The number of blades on fans in the US is more than three, and some primarily focus on their show rather than performance.

The reasons for this are listed below:

1. Countries like the US are colder, and in summers, all the places are almost centrally air-conditioned; the fans are used only in addition to air-conditioners. These fans are supposed to move at a slow speed to keep the cold air coming from the air conditioner circulating in the room. Therefore, fans are only used to help the cool air circulate throughout the room.

However, ceiling fans in India are used to provide air in every corner of the room. Ceiling fans in India are considered to be an economical option, and they help in saving a hefty amount of money that is incurred on electricity bills.

2. The total number of blades in a fan plays an important role in its efficiency. The more the number of blades, the more the fan is going to chop the air. A fan with three blades remains balanced and is able to provide a good amount of air that is much more effective in beating the tropical heat of a country like India. With fewer blades, the fan can operate at higher speeds and prove to be more efficient.

By increasing the total number of blades, it creates an aerodynamic drag on the motor body, thereby decreasing the cost-efficiency of it. Hence, three blade ceiling fans in India are the best option.

Another reason for fans with higher blades being commonly used in countries like the US is their affordability. They are used as an addition to the lighting fixtures and must run at a low speed. Since these fans are heavier and their prime focus is not just providing air, they can afford to have more than three blades.

How does a capacitor help a fan to rotate?