Synchronous & Induction Machines

Voltage regulation of three phase Alternators-Direct loading, EMF Method, MMF Method, Potier Method,ASA Method -Numerical Problems. Blondel’s two reaction theory, Phasor Diagram under lagging power factor, Determination of Xd and Xq by slip test, Power developed by a Salient pole machine, Numerical Problems. Parallel Operation of Alternators- Necessary Conditions, Synchronisation- Synchronising current, Power and Torque, Effect of reactance, Numerical Problems, Methods of Synchronisation.

Principle of Synchronous Motor, Equivalent circuit, Phasor diagrams, Power flow diagram and equations, Losses and efficiency -Numerical Problems, Power-angle Characteristics, V Curve and Inverted V Curves. Three phase Induction motor – Constructional features, Expressions for Power and TorqueTorque- Slip characteristics, Phasor diagram, Equivalent Circuit of Induction motor- Tests on Induction motors for determination of equivalent circuit-Numerical Problems.

Performance of three phase Induction motors using Circle diagram, Numerical Problems. Cogging and Crawling in cage motors, Double cage Induction motor-Torque-Slip Characteristics. Starting of Induction motors – Types of Starters – DOL starter, Autotransformer Sta rter, Star Delta starter, Rotor Resistance Starter-Numerical Problems. Braking of Induction motors – Plugging, Dynamic braking, Regenerative braking Speed control – Stator Voltage control, V/f control, Rotor Resistance Control.

Induction generator – Principle of operation, Grid Connected and Self Excited Operation of Induction Generators, Torque-Slip Characteristics of an Induction machine. Single phase Induction motors-Double field revolving theory, Equivalent Circuit, Torque-Slip Characteristics, Types of Single Phase Induction motor, Applications. Selection of AC motors for different applications.