STARTING PERFOMANCE OF INDUCTION MOTORS Presentation - 1 BY: LUNGELO KHUMALO MDUDUZI THABEDE SABELO SHEZI SPHAMANDLA MBAMBO Presentation 1 Outline Exordium What is an induction motor ? Construction of an induction motor Working of an induction motor Types of induction motor Applications of an induction motor Performance characteristics Advantages and disadvantages of induction motors Presentation 2 Outline Precaution taken before motor start Starting analysis of induction motor Starting analysis of an induction motor Magnetic flux density distribution Eddy current density distribution Starting methods of three phase induction motor Factors affecting starting performance of induction motors Protection system of induction motor Presentation 3 Outline Comparison between types of induction motors performance Conclusion 1.1 Exordium Nikola Tesla is the inventor of the induction motor with a wrapped rotor. Tesla established the groundwork for understanding how a motor works in his scientific studies. A 100 horsepower (74.6 kW) motor from 1976 takes up the same amount of space as a 7.5 horsepower (5.5 kW) motor from 1897 Induction motor is sometimes referred to as a rotating transformer. Induction motors are widely utilized particularly polyphaser induction motors, which are employed frequently in industrial drives. An induction motor is a type of an asynchronous AC motor, because it runs at the speed less than synchronous. The flux generated by the revolving magnetic field in the stator will cause the rotor to rotate, but due to the lag between the flux current in the rotor and the flux current in the stator, the rotor will never attain its rotational magnetic field speed. 1.2. What is an induction motor? The most modest electrical machine from the construction point of view, in the majority of the cases Induction machines are the most common type of motor used in industrial, commercial, or residential settings Induction motors (also known as asynchronous motor) is a commonly used AC electric motors The rotating magnetic field produced in the stator will create flux in the rotor, hence causing the rotor to rotate. 1.3 Construction of an induction motor Like other types of motors, induction motors are made up of two main parts, stator and rotor The rotor and stator are separated by a small air gap ranges from 0.5 mm to 4 mm Stator: The stator is the stationary part of the motor. It consists of a steel frame which encloses a hollow cylindrical core. To make a three- or single-phase winding, coils are inserted in slots. Construction of an induction motor Rotor: The rotor of an induction motor is a hollow cylindrical laminated core, having slots on its outer periphery. The rotor windings are placed in these rotor slots. The rotor of induction motor is of two types Squirrel Cage Type Rotor Wound Type or Slip-Ring Type Rotor 1.4 Working of an induction motor Alternating flux is produced around the stator winding due to AC supply. The relative speed between stator Rotating Magnetic Field and rotor conductors causes an induced emf in the rotor conductors (Faraday's law of electromagnetic induction) Induced current in rotor will also produce alternating flux around it/ The production of rotor current is the relative velocity between rotating stator flux and the rotor. The rotor rotates in the same direction as that of stator flux to minimize the relative velocity 1.5 Types of induction motor Induction motors are classified into two types namely single phase induction motor and threephase induction motor. As their name suggests, a single-phase induction motor is connected to a single-phase AC power supply whereas the three-phase induction motor can be connected to a three-phase AC power supply. these types of induction motor are classified into some subcategories. Single-phase is classified into four types whereas 3-phase is classified into two types. Types of induction motors Single-phase induction motor (not self starting) Split Phase Capacitor Start Capacitor Run Shaded Pole Induction Motor Three-phase induction motor (self starting) Squirrel Cage Rotor Slip ring Rotor 1.6 Applications of an induction motor Single Phase: Single phase induction motor are used in low-power applications and widely used in domestic applications as well as industrial. And some of those are mentioned below. Pumps Compressors Small fans Electric shavers Three Phase: It is mostly used in industrial drives because it is very reasonable and vigorous, economical and reliable and some of other are mention below. Conveyor Large capacity exhaust fans Cranes Hoists 1.7 Advantages and Disadvantages of induction motor Advantages of a three phase induction motor: They have a simple design and a strong structure that makes them long-lasting and simple to operate. In comparison to single-phase induction motors, the cost of maintenance for three-phase induction motors is significantly lower. The fact that three-phase induction motors are self-starting and do not require any additional mechanism to start the rotor rotation is the most noticeable attribute that makes them popular in the industry. A three-phase induction motor operates on a uniformly rotating magnetic field. Advantages and Disadvantages of an induction motor Disadvantages of a three phase induction motor: The three-phase induction motor draws more current during mild loads, due to it poor power factor. More electrical components are required to obtain speed control in a three-phase induction motor, resulting in a complex electrical system. The starting inrush current of an induction motor is very high. This results in a drop in voltage when the machine is switched on. Advantages and Disadvantages of an induction motor Advantages of a single phase induction motor: The single-phase induction motor has the advantage of being simple to assemble and construct. The operation of an induction motor is unaffected by the status of the environment. As a result, the motor is both powerful and long-lasting mechanically. Disadvantages of a single phase induction motor: Despite their basic simplicity, single-phase motors have been known to run slowly or overheat when the load is excessive. Furthermore, because single-phase motors do not self-start, they require additional circuitry for initiation, allowing for more short circuits and failures. References Induction Motor Working Principle," [Online]. Available: https://studiousguy.com/induction-motor-working-principle/. [Accessed 09 03 2022]. How does induction motor work?. [Sound Recording]. Lesics. 2018. P. miller, "Starting Performance Analysis of a Single Phase Induction Motor," JMAG Group, 11 Aug 2020. b. F. A. (Author), "Three Phase Induction Motors: Construction, Performance, Starting, Braking, Speed control and Design of Three Phase Induction Motors," p. 180 pages. U. 3. I. MOTORS. [Online]. Available: https://studylib.net/doc/18078404/unit-3.induction-motors. [Accessed 09 03 22]. Electrical4U, "Induction Motor: Working Principle, Types, & Definition," 3 May 2021. [Online]. Available: https://www.electrical4u.com/induction-motor-types-ofinduction-motor/. [Accessed 09 03 22] P. A. J, "Induction Motors: Main Types and Different Applications," 04 june 2020. [Online]. Available: https://www.researchdive.com/blog/induction-motors-maintypes-and-different-applications. [Accessed 09 03 22]. Thank You!
