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SYLLABUS

Unit-1

Magnetic Material Properties and Applications: Introduction – Magnetic materials and their properties – Magnetically induced emf and force – A.C operation of magnetic circuits – Hysteresis and eddy current losses – Permanent magnets, and applications of permanent magnet materials. Principles of Electromechanical Energy Conversion: Energy in magnetic system – Field energy and mechanical force – Multiply-excited magnetic field systems, forces/torques in systems with permanent magnets – Energy conversion via electric field – Dynamical equations of electro mechanical systems

Unit-2

D.C Generators Constructional details of D.C machine – Principle of operation of D.C generator – Armature windings and its types – EMF equation – Armature reaction – Effect of brush lead – Demagnetizing and cross magnetizing ampere turns – Compensating windings – Commutation – EMF induced in a coil undergoing commutation – Methods of improving commutation – OCC and load characteristics of different types of generators. Parallel Operation of D.C Generators: D.C shunt and series generators in parallel – Equalizing connections

Unit-3

D.C Motors Force on conductor carrying current – Back emf – Torque and power developed by armature, speed control of D.C motors(Armature control and Flux control methods) – Necessity of starters – constructional details of 3-point and 4-point starters – Characteristics of D.C motors – Losses in D.C machines – Condition for maximum efficiency Testing of D.C Machines: Brake test – Swinburne’s test – Hopkinson’s test – Fields test – Retardation test

Unit-4

Single Phase Transformers Principle – Construction and operation of single-phase transformers – Equivalent circuit – Phasor diagrams(no load and on load) – Magnetizing current – Effect of nonlinear B-H curve of magnetic core material – Harmonics in magnetization current – Losses and efficiency Testing - Open circuit and short circuit tests – Voltage regulation – Sumpner’s test – Separation of hysteresis and eddy current losses. Parallel operation of single-phase transformers – Autotransformers - Construction – Principle – Applications and Comparison with two winding transformer.

Unit-5

Three Phase Transformers Three-phase transformer – construction, Types of connection and their comparative features – Phase conversion - Scott connection – Tap-changing transformers – No-load and on-load tapchanging of transformers – Three-winding transformers – Cooling of transformers.