Nonlinear circuits – d.c circuits with one nonlinear element; its solution with example.
D.C. Transients: R-L & R-C transients – solution for current , voltage or charge as a function of time; time constants; R-L-C transients – under damped, over damped and critically damped conditions.
Single Phase A.C. Circuits:
Generation of single phase a.c. voltage and determination of average (mean) and RMS (effective) values of voltage and current with special reference to sinusoidal waveforms; Form factor and peak factor for various waves.
Representation of sinusoidal time varying quantities as phasors; concepts of reactance, impedance and their representation in complex forms using j operator.
Steady state analysis of series R-L-C circuit & its phasor diagram.
Concept of power & power factor; expression of power in complex notation.
Concept of admittance, susceptance in parallel circuits; calculation of branch currents in parallel circuits.
Analysis of series parallel circuits & phasor diagrams.
Resonance in series and parallel circuits.
Three phase A.C. Circuits:
Generation of 3-phase balanced sinusoidal voltage; star & delta connections; line & phase quantities (current & voltage).
Solution of 3-phase star/delta circuits with balanced supply voltage and balanced load; phasor diagram; 3-phase, 4-wire circuits.
Measurement of three phase power by two wattmeter method; phasor diagram with balanced load and determination of load power factor from wattmeter readings.
Ampere circuital law; magnetic circuit & its similarity with electric circuits; solution of series, parallel & series parallel magnetic circuits.
Iron losses – hysteresis & eddy current losses; relationship between B-H loop & hysteresis loss.
Energy stored in a magnetic field and force of attraction between pole faces.
Constructional features and principle of operation; concept of ideal transformer under no load & loaded conditions; its equivalent circuit. Practical transformer rating & its equivalent circuit.
Regulation – definition & importance; derivation of expression for it: Losses & efficiency, condition for maximum efficiency.
O.C & S.C. tests and determination of equivalent circuit parameters. Various types of three phase connections of transformers.
Autotransformer – principle of operation & relative advantages & disadvantages over a two winding transformer.
Introduction of general constructional features (stator, rotor & air gap); conditions for production of steady electromagnetic torque.
Multi polar machine & concept of mechanical & electrical angle and their relation; importance of the relation n = 2f/p.
Expression for generated emf in a coil rotating relative to a field.
Three phase induction motor:
Elementary balanced 3-phase distributed winding & production of revolving magnetic field; comment on its strength, speed and direction of rotation.
Constructional features and principle of operation; types of induction motors; definition of slip and its importance; relation between stator & rotor frequencies.
Per phase equivalent circuit; relation between air gap power, rotor copper loss and mechanical power developed; expression for electromagnetic torque developed.
Torque-slip characteristic, stable & unstable zones; modification of torque-slip characteristic for supply voltage, rotor resistance and frequency variation.
Basic principles of starting induction motor by direct on line, reactor, autotransformer, star-delta and rotor resistance starters.
Constructional features; elementary lap & wave windings; parallel paths in armature circuit.
EMF & torque expressions and their uses in both generating & motoring modes.
Classification of d.c. generators; characteristics of shunt, separately and compound generator; armature reaction & its effect.
Classification of d.c motors; characteristics of shunt & series motors. Starting of d.c shunt motor; 3-point starter for shunt motor.
Speed control of shunt and series motors; field of applications.
DC PMMC instruments – constructional feature and principle of operation; moving iron meters – construction and principle of operation.
Dynamometer type wattmeter; induction type energy meter construction & principle of operation.