UNIT - I D.C. Generators: Principle of operation - Action of commutator - constructional features - armature windings - lap and wave windings - simplex and multiplex windings - use of laminated armature - E. M.F Equation. Armature reaction - Cross magnetizing and de-magnetizing AT/pole - compensating winding - commutation - reactance voltage - methods of improving commutation. Methods of Excitation - separately excited and self-excited generators - build-up of E.M.F - critical field resistance and critical speed - causes for failure to self-excite and remedial measures. Load characteristics of shunt, series and compound generators. (Chapter - 1) UNIT - II D.C Motors: Principle of operation - Back E.M.F. - Torque equation - characteristics and application of shunt, series and compound motors - Armature reaction and commutation. Speed control of D.C. Motors - Armature voltage and field flux control methods. Motor starters (3-point and 4-point starters) Testing of D.C. machines - Losses - Constant & Variable losses - calculation of efficiency - condition for maximum efficiency. (Chapter - 2) UNIT - III Testing of DC Machines: Methods of Testing - direct, indirect, and regenerative testing - Brake test - Swinburne’s test - Hopkinson’s test - Field’s test - separation of stray losses in a d.c. motor test. (Chapter - 3) UNIT - IV Single Phase Transformers: Types - constructional details-minimization of hysteresis and eddy current losses- EMF equation - operation on no load and on load - phasor diagrams. Equivalent circuit - losses and efficiency - regulation - All day efficiency - effect of variations of frequency & supply voltage on iron losses. (Chapter - 4) UNIT - V Testing of Transformers and Poly-Phase Transformers: OC and SC tests - Sumpner’s test - predetermination of efficiency and regulation-separation of losses test-parallel operation with equal and unequal voltage ratios - auto transformers-equivalent circuit - comparison with two winding transformers.