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Electric Motor - Dc Motor, Types Of Dc Motor, Ac Motors, Principles Of Three Phase Motor Operation

electrical magnetic field rotor

An electric motor is a machine used to convert electrical energy to mechanical energy. Electric motors are extremely important to modern-day life, being used in many different places, e.g., vacuum cleaners, dishwashers, computer printers, fax machines, video cassette recorders, machine tools, printing presses, automobiles, subway systems, sewage treatment plants and water pumping stations.

The major physical principles behind the operation of an electric motor are known as Ampère's law and Faraday's law. The first states that an electrical conductor sitting in a magnetic field will experience a force if any current flowing through the conductor has a component at right angles to that field. Reversal of either the current or the magnetic field will produce a force acting in the opposite direction. The second principle states that if a conductor is moved through a magnetic field, then any component of motion perpendicular to that field will generate a potential difference between the ends of the conductor.

An electric motor consists of two essential elements. The first, a static component which consists of magnetic materials and electrical conductors to generate magnetic fields of a desired shape, is known as the stator. The second, which also is made from magnetic and electrical conductors to generate shaped magnetic fields which interact with the fields generated by the stator, is known as the rotor. The rotor comprises the moving component of the motor, having a rotating shaft to connect to the machine being driven and some means of maintaining an electrical contact between the rotor and the motor housing (typically, carbon brushes pushed against slip rings). In operation, the electrical current supplied to the motor is used to generate magnetic fields in both the rotor and the stator. These fields push against each other with the result that the rotor experiences a torque and consequently rotates.

Electrical motors fall into two broad categories, depending on the type of electrical power applied-direct current (DC) and alternating current (AC) motors.

The first DC electrical motor was demonstrated by Michael Faraday in England in 1821. Since the only available electrical sources were DC, the first commercially available motors were of the DC type, becoming popular in the 1880s. These motors were used for both low power and high power applications, such as electric street railways. It was not until the 1890s, with the availability of AC electrical power that the AC motor was developed, primarily by the Westinghouse and General Electric corporations. Throughout this decade, most of the problems concerned with single and multi-phase AC motors were solved. Consequently, the principal features of electric motors were all developed by 1900.


Electric Vehicles - Batteries, Advantages, Hybrids, Challenges Still Exist [next] [back] Electric Current - The Speed Of An Electric Current, Electric Current And Energy, Electric Current And Magnetism, Alternating Current - Current and the transfer of electric charge, Direct current

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An electric motor





is a machine used to convert electrical energy to mechanical energy. Electric motors are extremely important to modern-day life, being used in many different places, e.g., vacuum cleaners, dishwashers, computer printers, fax machines, video cassette recorders, machine tools, printing presses, automobiles



, subway systems, sewage treatment plants and water pumping stations.



The major physical principles behind the operation of an electric motor are known as Ampère's law and Faraday's law. The first states that an electrical conductor sitting in a magnetic field will experience a force if any current flowing through the conductor has a component at right angles to that field. Reversal of either the current or the magnetic field will produce a force acting in the opposite direction. The second principle states that if a conductor is moved through a magnetic field, then any component of motion perpendicular to that field will generate a potential difference between the ends of the conductor.



An electric motor consists of two essential elements. The first, a static component which consists of magnetic materials and electrical conductors to generate magnetic fields of a desired shape, is known as the stator. The second, which also is made from magnetic and electrical conductors to generate shaped magnetic fields which interact with the fields generated by the stator, is known as the rotor. The rotor comprises the moving component of the motor, having a rotating shaft to connect to the machine being driven and some means of maintaining an electrical contact between the rotor and the motor housing (typically, carbon brushes pushed against slip rings). In operation, the electrical current supplied to the motor is used to generate magnetic fields in both the rotor and the stator. These fields push against each other with the result that the rotor experiences a torque and consequently rotates.



Electrical motors fall into two broad categories, depending on the type of electrical power applied-direct current (DC) and alternating current (AC) motors.



The first DC electrical motor was demonstrated by Michael Faraday in England in 1821. Since the only available electrical sources were DC, the first commercially available motors were of the DC type, becoming popular in the 1880s. These motors were used for both low power and high power applications, such as electric street railways. It was not until the 1890s, with the availability of AC electrical power that the AC motor was developed, primarily by the Westinghouse and General Electric corporations. Throughout this decade, most of the problems concerned with single and multi-phase AC motors were solved. Consequently, the principal features of electric motors were all developed by 1900.







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Additional Topics

Electric Motor - Dc Motor

The operation of a DC motor is dependent on the workings of the poles of the stator with a part of the rotor, or armature. The stator contains an even number of poles of alternating magnetic polarity, each pole consisting of an electromagnet formed from a pole winding wrapped around a pole core. When a DC current flows through the winding, a magnetic field is formed. The armature A cross sect…



Electric Motor - Types Of Dc Motor

DC motors are more common than we may think. A car may have as many as 20 DC motors to drive fans, seats, and windows. They come in three different types, classified according to the electrical circuit used. In the shunt motor, the armature and field windings are connected in parallel, and so the currents through each are relatively independent. The current through the field winding can be control…



Electric Motor - Ac Motors

Electric Motor - Principles Of Three Phase Motor Operation

The main difference between AC and DC motors is that the magnetic field generated by the stator rotates in the ac case. Three electrical phases are introduced through terminals, each phase energizing an individual field pole. When each phase reaches its maximum current, the magnetic field at that pole reaches a maximum value. As the current decreases, so does the magnetic field. Since







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