The components of A.C current will vary with time. Fig: 4 A Magnetic field is produced around the single wire and simplified winding Now for this special arrangement, the magnetic field produced by 3 phase A.C current will be as shown at a particular instant. A wire carrying current produces a magnetic field around it. To understand the phenomenon of a rotating magnetic field, it is much better to consider a simplified 3 phase winding with just 3 coils. Fig: 3 Rotating magnetic field is produced in an induction motor The concept of a Rotating Magnetic Field (RMF) We will see how this is produced in the next section. RMF is an important concept in electrical machines. As shown in the figure below a magnetic field is produced which is rotating in nature. It produces a rotating magnetic field (RMF). When a 3 phase AC current passes through the winding something very interesting happens. Fig: 2 Construction details of the stator Effect of 3 phase current passing through a stator winding Winding passes through slots of the stator. Here only few of the steel laminations are shown. The way the steel laminations are arranged inside the frame is shown in the following figure. Fig: 1 Stator and rotor of an induction motor Construction details of a statorĪ Stator is made by stacking thin-slotted highly permeable steel laminations inside a steel or cast iron frame. The value of the radial air-gap may vary from 0.5 to 2 mm. There will be a small gap between rotor and stator, known as air-gap. The stator is basically a 3 coil winding and three phase AC power input is given to it. The Stator is the stationary part and the rotor is the rotating part. Parts of an induction motorĪn induction motor has 2 main parts the Stator and Rotor (Fig:1). Let’s get into the workings of induction motors, or more specifically, into Nikola Tesla’s genius thinking. In fact, about 50 percent of global electric power consumption is due to induction motors. This hundred-year-old motor-invented by the great scientist Nikola Tesla-is the most common motor type, even today. The invention of induction motors permanently altered the course of human civilization. How does an Induction Motor work ? September 26, 2019
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