INDUSTRIAL CONTROL SYSTEMSSingle-Phase Induction MotorsOne of the famous members of the huge family of AC motors is the single-phase induction motor. This type of motor is for converting electrical energy to mechanical e
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INDUSTRIAL CONTROL SYSTEMSSingle-Phase Induction MotorsOne of the famous members of the huge family of AC motors is the single-phase induction motor. This type of motor is for converting electrical energy to mechanical energy to conduct some physical tasks. To do their job properly, this induction motor needs only one power phase. They are often used in low-power applications such as domestic and light-industrial use. Easy and simple construction, cheap cost of maintenance, great reliability, and low cost of repair are some of its considerable advantages. The following sections, we will elaborate on the construction, working principle, and types of single-phase induction motors. Stay with us.Single-Phase Induction Motor DesignThe two main components of the single-phase induction motor are the stator and rotor. As you may know and what you perceive from the name, the Stator is the stationary part of this motor. On the other hand, the rotor is the rotating component of the motor. the single-phase alternating supply reaches to the stator winding. Rotor with the assistance of a shaft is connected to the mechanical load. The rotor has a laminated iron core with many slots that are skewed. These rotor slots are closed or semi-closed type. The rotor windings are symmetrical.There is an air gap between the rotor and the stator. The most common usages of this motor are in refrigerators, clocks, drills, pumps, washing machines, and more. The stator winding in the induction motors is divided into two components: the main winding and the auxiliary winding. the position of these two types of windings is in a way that the auxiliary winding is perpendicular to the main winding. For your information, in induction motors, the main winding is the winding with more turns while another one is called auxiliary winding. Working Principle of the Single-phase Induction MotorThe previous section gave you some information about the construction and the design of the single-phase induction motors. Now that you know some parts of this kind of induction motor, let’s see what working principle rules over the operation of this construction.As mentioned before, a single-phase AC supply is given to the stator winding. After the stator winding receives the power supply, a magnetic field is produced which strikes in a sinusoidal manner. After a while, the polarity of the magnetic field reverses and the alternating flux cannot provide the required rotation force to the motor. As you may know, for the working of any electrical motor we need two fluxes.The interaction of these two fluxes produced the required torque. With the application of a single-phase AC supply to the stator winding, the alternating current starts moving through the stator. This alternating current produces an alternating flux and it is called main flux. the main flux also links with the rotor conductors.According to Faraday’s law of electromagnetic induction, emf gets induced in the rotor. As the rotor circuit is closed one so, the current starts moving in the rotor. This current called the rotor current produces its flux called rotor flux. Since this flux is produced due to the induction principle so, the motor working on this principle got its name as an induction motor.Types of Single-Phase Induction MotorIn the previous section, you read about the conditions and principle that a single-phase induction motor works depending on them. Now it is time to know more about the different types of single-phase induction motor. Based on the different methods for starting the single-phase IM, there are four main different types that we are going to deliver some useful information about each of them in the following sections.Split Phase Induction MotorThis type of single-phase IM is Also known as resistance starts motor. In this type, you will find the main winding and the auxiliary winding displaced by 90 degrees. The auxiliary winding and a centrifugal switch are connected in series. This switch’s job is to cut off the auxiliary winding from the main circuit when the motor speed reaches the speed up to 75 – 80 percent of the synchronous speed.Some characteristics of a split-phase induction motor include a power rating from 60 to 250W, constant speed, and high starting current. Because of the low cost of motor maintenance and repair, it is very popular in the market. Some domestic applications make use of this motor effectively. Remember that due to its low starting torque, it cannot drive more than 1kW.
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