19-04-2017, 07:34 PM
Special electrical machines book
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torrent special electrical machines e g janardanan pdf
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25-04-2017, 10:10 AM
In electrical engineering, electric machine is a general term for electric motors and electric generators and other electromagnetic machines. They are electromechanical energy converters: an electric motor converts electricity into mechanical energy, while an electric generator converts mechanical energy into electricity. The moving parts of a machine can rotate (rotating machines) or linear (linear machines). In addition to motors and generators, a third category often includes transformers, which although they have no moving parts are also power converters, by changing the voltage level of an alternating current.
Electric machines, in the form of generators, produce practically all electrical energy on Earth, and in the form of electric motors they consume approximately 60% of all electrical energy produced. Electric machines were developed from the mid-nineteenth century and have since been an omnipresent component of infrastructure. Developing more efficient electric machine technology is crucial to any global conservation strategy, green energy or alternative energy.
An electric generator is a device that converts mechanical energy into electrical energy. A generator forces the electrons to flow through an external electrical circuit. It is somewhat similar to a water pump, which creates a flow of water, but does not create water inside. The source of mechanical power, the primary engine, may be an alternating or turbine steam engine, water falling through a turbine or a hydraulic wheel, an internal combustion engine, a wind turbine, crank, compressed air, or any Another source of mechanical energy.
The two main parts of an electric machine can be described in mechanical or electrical terms. In mechanical terms, the rotor is the rotating part, and the stator is the stationary part of an electric machine. In electrical terms, the armature is the power producing component and the field is the magnetic field component of an electric machine. The armature may be in the rotor or in the stator. The magnetic field may be provided by any of the electromagnets or permanent magnets mounted on the rotor or stator. Generators are classified into two types, AC generators and DC generators.
AC generator
An AC generator converts mechanical energy into AC electricity. Because the power transferred to the field circuit is much less than the power transferred to the armature circuit, AC generators almost always have the field winding in the rotor and winding the armature in the stator.
AC generators are classified into several types.
• In an induction generator, the magnetic flux of the stator induces currents in the rotor. The primary motor then drives the rotor above the synchronous speed, causing the opposite rotor flow to cut the stator coils producing active current in the stator coils, thereby sending the power back to the mains. An induction generator draws reactive energy from the connected system and therefore can not be an isolated source of energy.
• In a synchronous generator (alternator), the current for the magnetic field is provided by a separate direct current source.
Direct Current Generator
An electric generator is a machine that converts mechanical energy into electrical energy. An electric generator operates based on the principle that when the conductor cuts off the magnetic field, an emf will be induced which will cause the current to flow if the conductor circuit is closed. From Simple loop Generator as an example.
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