Synchronous machine by Mitesh Kumar

Synchronous machine by Mitesh Kumar

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  HALDIA INSTITUTE OFTECHNOLOGY SYNCHRONOUS MACHINE BY:-Mitesh kumar Roll no. :- 13/EI/26 Univesity Roll no. :- 10300513026 Applied Electronics & Instrumentation Engg.
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  Introduction •A synchronous machineis a most important type of electric machine. •Synchronous Machine used at generating stations are known as Synchronous Generators or Alternators •Synchronous motors are widely used in Industries and are well known for their const. speed operation •Electromechanical energy conversion occurs whenever a change in flux is associated with mechanical motion
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  Construction of SynchronousMachine It consists of:  Stator  Rotor  Field Windings (On rotor)  Armature Windings (On Stator)
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  Diagram
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   It isa stationary member  It is the cylindrical portion inside which the rotor rotates  An air gap is provided between the stator and the rotor  Armature winding are 3 phased and are housed in the slots cut in the stator  It consists of cast iron stator frame, a cylindrical laminated , a cylindrical laminated and uniformly slotted core
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   Rotor isthe rotating part of the machine  Can be classified as: (a) Cylindrical Rotor and (b) Salient Pole rotor  Large salient-pole rotors are made of laminated poles retaining the winding under the pole head.
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   Armature windingsconnected are 3-phase and are either star or delta connected  The windings are 120 degrees apart and normally use distributed windings
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  The 3-phase armaturewinding is distributed in the slots along the armature air gap periphery For example: Consider that we have 18 slots, 2-pole 3-phase winding.. Hence we have 9 slots/per pole as shown figure
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   The windingdiagram of phase ‘a’ can be shown as:  Similarly, phase ‘b’ and phase ‘c’ are distributed in same manner
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   The fieldwinding of a synchronous machine is always energized with direct current  Under steady state condition, the field or exciting current is given Ir = Vf/Rf Vf = Direct voltage applied to the field winding Rf= Field winding Resistance
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  The mmf-phase graphcan be drawn as:  This implies that per phase emf is getting divided in each phase.  When all the 3-phase are connected then mmf-phase graph for each phase is displaced by 120 degrees
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   Mostly allthe synchronous machines use Distributed winding  Attempt is made to use all the slots available under a pole for the winding which makes the nature of the induced e.m.f. moe sinusoidal  Consider a sync. Machine with 3-phase winding, Slots, s= 18 slots Poles=2 slots per pole, g= s/p= 9 slots/pole/phase= g/3 = 3
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  Thank you