Electrical Machines - I

Electrical Machines - I

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Basic Concepts of Rotating MachinesPrinciples of electromechanical energy conversion Single and multiple excited systems m.m.f of distributed A.C. windings Rotating magnetic field Generated voltage Torque in round rotor machine.D.C. GeneratorsConstructional details emf equation Methods of excitation Self and separately excited generators Characteristics of series, shunt and compound generators Armature reaction and commutation Parallel operation of DC shunt and compound generators.D.C. Motors Principle of operation Back emf and torque equation Characteristics of series, shunt and compound motors Starting of DC motors Types of starters Speed control of DC series and shunt motors.Transformers Constructional details of core and shell type transformers Types of windings Principle of operation emf equation Transformation ratio Transformer on no-load Parameters referred to HV / LV windings Equivalent circuit Transformer on load Regulation Parallel operation of single phase transformers Autotransformer Three phase transformers Vector group.Testing of DC Machines and Transformers Losses and efficiency in DC machines and transformers Condition for maximum efficiency Testing of DC machines Brake test, Swinburne s test, Retardation test and Hopkinson s test Testing of transformers Polarity test, load test, open circuit and short circuit tests All day efficiency.A 300 V, d.c. shunt motor has armature and field resistances as 0.05 Q and 150 fl respectively. Calculate the additional resistance required in the field circuit to increase the speed of the motor from 750 r.p.m. to 1150 r.p.m. The current drawn anbsp;...

Title:Electrical Machines - I
Author:M.V.Bakshi U.A.Bakshi
Publisher:Technical Publications - 2008-01-01


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