A synchronous machine is called synchronous because their speed is directly link up to the frequency of the line by the equation ¥øs = [2¥ðf / (p/2)] , where p is the number of magnetic poles designed into each machine. handle other electrical machines, synchronous machines may be operated every as a motors or generators. There atomic number 18 iv basic parts to a synchronous machine - the rotor, the stator, the roll and stadium windings, and the exciter. When balanced three-phase currents flow in the windings, magnetic poles are produced on the inner surface of the stator. As the currents alternate in snip sequence - 120¡Æ apart in time - these magnetic poles move from group to group along the stator surface to produce a rotating magnetic field. The speed of this gyration is given by ¥øs in the above equation. The rotors are simply rotating electromagnets or permanent magnets built to have as many poles as are produced by the stator winding. electromagnetic rotor poles are magnetized by dc currents menstruum in the field coils surrounding each pole. The magnetic field produced by the rotor poles locks in with the rotating stator field, so that the do it and the stator field rotate in synchronism. The rotors of synchronous machines sire in two different types - salient pole and cylindric.
large pole machines are too weak mechanically and scram too much noise and wind resistance to be used in large generators. For machines such as generators, hard cylindrical rotors must be used which will endure the necessary strength without the noise and wind resistance. Since were not truly concerned with the construction of the synchronous machines rotor, we will assume cylindrical rotors for the purposes of this paper. To more fully understand synchronous machines, we will go out at a brief overview of...
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