I think putting resistance in series will reduce input voltage to motor which may affects motor life.
to decrease the speed of an ac motor used resistors but the type of resistor effect the motor life. you have to put resistor of the rating which a motor energy consume. dont be panic and try your best.if you tell me the power of motor then i'll tell you the rating of resistor used to reduce the speed of motor
You can if it is single phase by sacrifying efficiency and wasting energy.
Theoretically most things are assumed Ideal. But experimentally any loads applied will reduce lifespan. It basically forces electrons to flow through the resistors and reduces the overall potential by converting some of its energy into heat and other forms of energy. Over time this reduces the efficiency of the system that was once considered to be in steady state.
This will work with some kinds of AC motors and not work at all with other types. Speed of most AC motors is controlled by line frequency and how the motor is wound (how many poles.) Varying the voltage is not effective in changing the speed of this type motor.
An AC motor must always be supplied with its specification voltage. Reducing voltage would work in contrary to the case of a normal resistance, as the motor would tend to draw more current to meet its power rating. More current means more heat and, consequently, shorter life.
