Applications. Motor start and run capacitors are used in single-phase AC induction motors. Such motors are used whenever a single-phase power supply is more practical than a three-phase power supply, such as in domestic appliances. They are not as efficient as three-phase AC induction · Single-phase induction motors, like a 3 phase motor, runs by the principle of emf induction due to flux. But unlike 3 phase motors, single-phase motors run on a single-phase supply. Single-phase motors starting methods are governed by two well-established theories, namely the Double Revolving field theory and the Crossfield theory · The construction of the rotor of the single-phase induction motor is similar to the squirrel cage three-phase induction motor. The rotor is cylindrical and has slots all over its periphery. The slots are not made parallel to each other but are a little bit skewed as the skewing prevents magnetic locking of stator and rotor teeth and makes the working of induction motor more smooth and quieter
Induction Vs. Permanent Magnet Motor Efficiency | Auto Electrification
Ed Edwards. Three-phase motors also annotated numerically as 3-phase motors are widely used in industry and have become the workhorse of many mechanical and electromechanical systems because of their relative simplicity, proven reliability, and long service life. Three-phase motors are one example of a type of induction motor, also known as an asynchronous motor, that operates using the principals of electromagnetic induction.
While there are also single-phase induction motors available, those types of induction motors are used less frequently in industrial applications but are widely used in domestic applications such as in vacuum cleanersrefrigerator compressors, and air conditionersowing to the use of single-phase AC power in homes and offices.
In this article, we will discuss what a three-phase motor is and describe how it operates. To access other resources about motors, consult one of our other motor guides covering AC motorsDC motorsInduction motorsor the more general article on the types of motors, industrial applications of single phase induction motor. A full list of related motor articles is found industrial applications of single phase induction motor the section on related articles. In electrical power generation, alternating current AC that is created by a generator has the characteristic that its amplitude and direction changes with time, industrial applications of single phase induction motor.
If shown graphically with the amplitude on the y-axis and time on the x-axis, the relationship between the voltage or current vs.
time would resemble a sine wave as shown below:. Electrical power carried to homes is single-phase, industrial applications of single phase induction motor, meaning that there is one current-carrying conductor plus a neutral connection and a ground connection. If viewed graphically, each phase would appear as a separate sine wave, which then combines as shown in the image below:.
Three-phase motors are powered from the electrical voltage and current that is generated as three-phase input power and is then used to produce mechanical energy in the form of a rotating motor shaft. Three-phase motors are a type of AC motor that is a specific example of a polyphase motor. These motors can be either an induction motor also called an asynchronous motor or a synchronous motor. The motors consist of three main components — the stator, the rotor, industrial applications of single phase induction motor, and the enclosure.
The stator consists of a series of alloy steel laminations around which are wound with wire to form induction coils, one coil for each phase of the electrical power source. The stator coils are energized from the three-phase power source.
The rotor also contains induction coils and metal bars connected to form a circuit. The rotor surrounds the motor shaft and is the motor component that rotates to produce the mechanical energy output of the motor. The enclosure of the motor holds the rotor with its motor shaft on a set of bearings to reduce the friction of the rotating shaft.
The enclosure has end caps that hold the bearing mounts and house a fan that is attached to the motor shaft which spins as the motor shaft turns. The spinning fan draws ambient air from outside the enclosure and forces the air across the stator and rotor to cool the motor components and dissipate heat that is generated in the various coils from the coil resistance.
The enclosure also typically has raised mechanical fins on the exterior that serve to further conduct heat to the outside air. The end cap will also provide a location to house the electrical connections for the three-phase power to the motor. Three-phase motors operate by the principle of electromagnetic induction which was discovered by the English physicist Michael Faraday back in Faraday noticed that when a conductor such as a coil or loop of wire, is placed in a changing magnetic field, there is an induced electromotive force or EMF that is generated in the conductor.
He also observed that current flowing in a conductor such as wire will generate a magnetic field and that the magnetic field will vary as the current in the wire changes in either magnitude or direction.
This is expressed in mathematical form by relating the curl of the electric field to the rate of change in time of the magnetic flux:. Figure 3 below is an illustration of Faraday's law of induction. Note that the presence of an EMF depends on the motion of the magnet which results in a changing magnetic field to exist. For induction motors, when the stator is powered from a three-phase electrical energy source, each coil generates a magnetic field whose poles north or south change position as the AC current oscillates through a complete cycle.
Since each of the three phases of the AC current are phase-shifted by othe magnetic polarity of the three coils are not all identical at the same instant of time. This condition results in the stator producing what is known as an RMF or Rotating Magnetic Field. As the rotor sits in the center of the stator coils, the changing magnetic field from the stator industrial applications of single phase induction motor a current in the rotor coils, which in turn results in an opposing magnetic field being generated by the rotor.
The rotor field seeks to align its polarity against that of the stator field, the result being a net torque is applied to the motor shaft and it begins to rotate as it seeks to bring its field into alignment. Note that in the 3-phase induction motor, there is no direct electrical connection to the rotor; magnetic induction causes the motor rotation. With three-phase induction motors, the rotor seeks to maintain alignment with the RMF of the stator, but never achieves it, which industrial applications of single phase induction motor why induction motors are also called asynchronous motors.
The phenomenon which causes the rotor speed to lag the speed of the RMF is known as slip, as is expressed as:. where N r is the speed of the rotor, and N s is the synchronous speed of the rotating field RMF of the stator. Synchronous motors operate in a similar fashion to induction motors except that in the case of a synchronous motor, the stator and rotor fields are locked into alignment so that the industrial applications of single phase induction motor RMF will cause the rotor to turn at the exact same rate of rotation in synch — therefore the slip is equal to 0.
For more information on how this is accomplished, refer to these articles on reluctance motors and brushless DC motors. Note that synchronous motors, unlike induction motors, need not be powered by AC power. The speed that is generated by a three-phase AC motor is a function of the AC supply frequency since it is the source of the RMF in the stator coils.
Therefore, some AC motor controllers operate by using the AC current input to generate a modulated or controlled frequency input to the motor, thereby controlling the speed of the motor. Another approach that can be used to control motor speed is by altering the slip described earlier, industrial applications of single phase induction motor.
If the slip increases, the motor speed i. the speed of the rotor decreases. To learn more about the approaches for motor control, review our article on AC Motor Controllers. This article presented a brief discussion of what 3-phase motors are and how they operate. To learn more about motors, explore our related articles listed below. For information on other products, consult our additional guides or visit the Thomas Supplier Discovery Platform to locate potential sources of supply or view details on specific products.
Guides Ed Edwards Share:. Select From OverIndustrial Suppliers. Receive Daily Industry Updates. Search Over 6 Million Products.
Start Sourcing Suppliers List Your Business ico-arrow-default-right. Thomas uses cookies to ensure that we give you the best experience on our website. By using this site, you agree to our Privacy Statement and our Terms of Use. Register or Sign-In to Continue ×.
3 ph induction motor ppt
· 3 ph induction motor ppt 1. Prof. AJAY B. BALAR Darshan Institute of Engineering & Technology, Rajkot (Gujarat) 2. Outlines: Introduction Types of Electrical Machines Types of 3-Ph induction motor Basic Principle Working Principle Compnents of induction motor Application Comparision between 1-ph I.M. & 3-ph I.M · The construction of the rotor of the single-phase induction motor is similar to the squirrel cage three-phase induction motor. The rotor is cylindrical and has slots all over its periphery. The slots are not made parallel to each other but are a little bit skewed as the skewing prevents magnetic locking of stator and rotor teeth and makes the working of induction motor more smooth and quieter · Single-phase induction motors, like a 3 phase motor, runs by the principle of emf induction due to flux. But unlike 3 phase motors, single-phase motors run on a single-phase supply. Single-phase motors starting methods are governed by two well-established theories, namely the Double Revolving field theory and the Crossfield theory
Keine Kommentare:
Kommentar veröffentlichen