Induction Motor: What Is A Induction Motor?

What is an induction motor?

Induction motors by the name, are AC motors in which they rely on the induction that occurs due magnetic field to produce torque in order to generate motion. So there is no force intervention in the starting or while operating the induction motor, as the main purpose of the induction motor is to convert electrical energy to mechanical energy, in order to operate other machines or appliances. The three phase induction motors are easily constructed and easily handled. The induction motor was first introduced in the late 19th century by a scientist called Nikola Tesla, in the early days, the induction motor had the same principle of operation and construction as today, the difference is that, the technology introduced new materials to fabricate wires and shafts and housing of the motor, thus enhances its performance and efficiency greatly.

The applications of induction motors:

The induction motor takes a huge part of the industry, as they are introduced in everyday applications for example, toys, water pumps, fans, washing machines and cars. The reason that the three phase induction motors are very popular is due to the simplicity of the mechanisms included, low cost availability, low risk of failure, economical and can produce large torques. Other reason that the three phase induction motor is widely used is that it can be easily handled and easily fabricated to suit all kinds of applications, the three phase induction motors can be manipulated to produce high or low torques and high or low speeds.

Sizes and power of induction motor:

This type of induction motors, with the power of technology and science, have reached a point where there are very small motors ranging from 0.1 hp to a huge 3000 hp motors, ...

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...expensive and has issues of torque losses.

The speed control of three phase induction motor:

The speed of the motor relies on the number of poles, frequency and slip. The speed equation is as follows: N = 120f/p (1-S). Where f is the supply frequency, p is the number of poles, s is the slip. So the method of controlling the speed is reliable on these factors, and the methods can be one of the methods introduced:

1- Pole changing

• So briefly the pole changing can be altered by using multiple stator windings, method of consequent poles and pole amplitude manipulation.

2- Supply frequency control

3- Rotor resistance control

• This method is only done in wound rotor motors, by adding resistance to the rotor circuit in the rotor bars, this will affect the torque-speed curves greatly. This method is affective and not expensive.

4- Stator voltage control

5- Slip recovery