Synchronous generator

Synchronous Generator, Alternator, construction of alternator,synchronous machines,working of synchronous generator,introduction to synchronous machines,AC machines

1. Contents: Introduction Construction Working principle Comparison of rotor References Kongunadu College of Engineering & Technology Synchronous Generator SYNCHRONOUS GENERATOR

2. Introduction Alternators (or) Synchronous generators  A Machine generating AC e.m.f Synchronous motors  A machine accepting i /p from AC supply to produce mechanical output Synchronous Speed: Alternators has to be rotated at a particular speed to keep the frequency of the generated e.m.f constant at required value Ns = 120f / P Ns  Synchronous speed f frequency P  No. of poles Kongunadu College of Engineering & Technology Synchronous Generator

3. CONSTRUCTION Stationary Armature winding Stator core use a laminated construction  Special steel stamping and insulated from each other with varnish or paper  Reduce the eddy current loss Steel material  Reduce hysteresis loss STATOR Kongunadu College of Engineering & Technology Synchronous Generator

4. CONSTRUCTION Projected pole type as all the poles are projected out from the surface of the rotor. Rotor have large diameter and small axial length ROTOR SALIENT POLE TYPE: Mechanical strength is less So it is preferred for low speed alternator (125 rpm to 500 rpm) Application: Water turbine , I.C engines Kongunadu College of Engineering & Technology Synchronous Generator

5. CONSTRUCTION Smooth solid steel cylinder, having no. of slots to accommodate field coils. Rotor have small diameter and large axial length ROTOR SMOOTH CYLINDRICAL OR NON-SALIENT POLE : Mechanical very strength So it is preferred for high speed alternator (turbo alternators) ( 1500 rpm to 3000 rpm) Application: Steam turbine , Electric motor Kongunadu College of Engineering & Technology Synchronous Generator

6. OPERATION TWO POLE ALTERNATOR: Principle: Faradays law of EMI  When there is a relative motion b/w the conductors and the flux, emf gets induced in the conductor. Kongunadu College of Engineering & Technology Synchronous Generator

7. OPERATION FOUR POLE ALTERNATOR: Kongunadu College of Engineering & Technology Synchronous Generator

8. The rotor winding is energized from the d.c . exciter and alternate N and S poles are developed on the rotor. When the three phase supply is given to the stator, the stator or armature conductors experience the force due to electromagnetic induction. Then the rotor starts to rotate. The speed of the motor is given by; N = 120f / P Where N = speed of rotor in r.p.m . , P = number of rotor poles. Kongunadu College of Engineering & Technology Synchronous Generator

9. Salient Pole Rotor Cylindrical Rotor 1. Used for low speed alternators 1. Used for high - speed turbo alternators 2 . Which is used in Hydro power plants 2. Which is used in Thermal power plants The use of salient pole and round rotor synchronous machines Kongunadu College of Engineering & Technology Synchronous Generator

10. Kongunadu College of Engineering & Technology Synchronous Generator S.No Book s / Web Sources 1 A.E. Fitzgerald, Charles Kingsley, Stephen. D. Umans , ‘Electric Machinery’, Tata Mc Graw Hill publishing Company Ltd, 2003. 2 D.P. Kothari and I.J. Nagrath , ‘Electric Machines’, Tata McGraw Hill Publishing Company Ltd, 2002. 3 P.S. Bhimbhra , ‘Electrical Machinery’, Khanna Publishers, 2003. 4 M.N.Bandyopadhyay , Electrical Machines Theory and Practice, PHI Learning PVT LTD., New Delhi, 2009. 5 K. Murugesh Kumar, ‘Electric Machines’, Vikas Publishing House Pvt. Ltd, 2002. 6 Syed A. Nasar , Electric Machines and Power Systems: Volume I, Mcgraw -Hill College; International ed Edition, January 1995. 7 J. Ganavadivel , ‘Electrical Machines II’, Anuradha publications, Fourth edition, 2015. 8 U.A.Bakshi & M.V.Bakshi , ”Electrical Machines II,” Technical Publications, Second revised edition, 2016. 9 Google and Wikipedia REFERENCES