The first ceiling fans appeared in the early 1860s and 1870s, in the United States. At that time, they were not powered by any form of electric motor. Instead, a stream of running water was used, in conjunction with a turbine, to drive a system of belts which would turn the blades of two-blade fan units. These systems could accommodate several fan units, and so became popular in stores, restaurants, and offices. The electrically powered ceiling fan was invented in 1882 by Philip Diehl
Principle behind the Ceiling Fan
The electric motor is the electric machine within the ceiling fan that converts electrical energy into mechanical energy. The ceiling fan capacitor torques up the electric motor, allowing it to start and run. An electrical current reaches the motor and then enters coils of wire that are wrapped around a metal base. As this current passes through the wire, a magnetic field is caused that expends force in a clockwise motion that actually changes the electric energy into mechanical energy. This action causes the motor coils to spin. As the coils are spinning, the fan captures this spinning motion, transferring it to the fan blades.
How the Ceiling Fan Cools
Fans do not actually cool air (if anything, electric fans warm it slightly due to the warming of their motors), but the breeze created by a ceiling fan speeds the evaporation of sweat on human skin, which makes the body feel cool. Thus, fans may become ineffective at cooling the body if the surrounding air is near body temperature and contains high humidity.
Since the fan works directly on the body, rather than by changing the temperature of the air, during the summer it is a waste of electricity to leave a ceiling fan on when no one is in a room.