Often, more than one independent three phase winding is on the stator. The armature winding is formed by interconnecting various conductors in slots spread over the periphery of the machine’s The stator of a synchronous machine carries the armature or load winding which is a three-phase winding.
Contoh sumber arus listrik ac dan dc generator#
An external dc generator used to provide current is called an “exciter. The brushes are made of a carbon compound to provide a good contact with low mechanical friction. Stationary contacts called brushes ride on these slip rings to carry current to the rotating field windings from the dc supply. In this case the leads from the field winding are connected to insulated rings mounted concentrically on the shaft. This current may be provided by an external dc generator or by a rectifier. Since the rotor poles have constant polarity they must be supplied with direct current. For these big machines, the rotor must be a solid, cylindrical steel forging to Synchronous MachineĪxial slots are cut in the surface of the cylinder to accommodate the field windings. Salient poles are too weak mechanically and develop too much wind resistance and noise to be used in large, high-speed generators driven by steam or gas turbines. The magnetic field produced by the rotor poles locks in with a rotating stator field, so that the shaft and the stator field rotate in synchronism. Synchronous machine rotors are simply rotatingĮlectromagnets built to have as many poles as are produced by the stator windings.ĭC currents flowing in the field coils surrounding each pole magnetize the rotor poles. Direct-conductor cooling (using Roto hydrogen or water as coolant) rĬylindrical-Rotor Synchronous Generator Stator Synchronous Machine Salient-Pole Synchronous Generator Stator t-pole rotorĬylindrical-Rotor Synchronous Generator D » 1 m Turbine Most hydraulic turbines have to turn at low speeds (between 50 and 300 r/min) Machines (steam-turbines) Synchronous Machineġ. Salient pole rotors are less expensive than round rotors.Ĭylindrical ( round) rotor – low speed machines (hydro-turbines) There are two types of rotors used in synchronous machines: cylindrical (or round) rotors and salient pole rotors.
AC windings are mounted on the (stationary) stator resulting in three-phase AC stator voltages and currents Or energy is stored in the magnetic field and eventually flows into the electrical circuit that powers theĭC field windings are mounted on the (rotating) rotor - which is thus a rotating electromagnet Since the current is alternating, the motor will run smoothly only at the frequency of the sine wave.Īs the rotor moves, there is a change in the energy storedĮither energy is extracted from the magnetic field (and becomes mechanical energy – motor) Mechanical rectifier called commutator to 'rectify' the emf produced.ĪC motor - No need rectification, so don’tĪs in the case, a current is passed through the coil, generating a torque on the coil. Medan putar stator akan memotong konduktor yang terdapat pada sisi rotor, akibatnya pada kumparan rotor akan timbul tegangan induksi ( ggl ) sebesarĮ = tegangan induksi ggl f = frekkuensi N = banyak lilitan Q = fluks Ns = kecepatan sinkron f = frekuensi sumber p = jumlah kutupĢ. Bila sumber tegangan tiga phasa dipasang pada kumpara stator, maka pada kumparan stator akan timbul medan putar dengan kecepatan Metode starting telah dapat dikembangkan kemudian hari, maka motor iniġ. , sehingga untuk starting diperlukan cara-cara tertentu. Sinkron adalah tidak mempunyai torka mula daya sehingga motor ini memilikiĮfisiensi tinggi. Dapat mengakibatkan adanya rugi-rugi Sedangkan kelemahan dari motor
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