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An alternator that uses a permanent magnet for its magnetic field is called a magneto. Alternators in power stations driven by steam turbines are called turbo-alternators. Large 50 or 60 Hz three-phase alternators in power plants generate most of the world's electric power, which is distributed by electric power grids. [4]
Dynamos and alternators require a source of power to drive their field coils. This could not be supplied by their own generator's output, without some process of ' bootstrapping '. Henry Wilde , an electrical engineer from Manchester, England, developed a combination of magneto and electro-magnet generator, where the magneto was used only to ...
Except for permanent magnet generators, a generator produces output voltage proportional to the magnetic flux, which is the sum of flux from the magnetization of the structure and the flux proportional to the field produced by the excitation current. If there is no excitation current the flux is tiny and the armature voltage is almost nil.
Calibration removes the need to know the density of the sample. Variable temperature measurements can be made by placing the sample in a cryostat between the pole pieces of the magnet. [1] The Evans balance. [2] is a torsion balance which uses a sample in a fixed position and a variable secondary magnet to bring the magnets back to their ...
Category: Alternators. 1 language. ... Permanent magnet synchronous generator This page was last edited on 31 December 2018, at 21:57 (UTC). ...
The simplest type of linear alternator is the mechanically powered flashlight (shake type). This is a torch (UK) or flashlight (USA) which contains a coil and a permanent magnet . When the appliance is shaken back and forth, the magnet oscillates through the coil and induces an electric current .
The rotating magnetic field is the key principle in the operation of induction machines.The induction motor consists of a stator and rotor.In the stator a group of fixed windings are so arranged that a two phase current, for example, produces a magnetic field which rotates at an angular velocity determined by the frequency of the alternating current.
Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other.Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, magnetism is one of two aspects of electromagnetism.