Electrical Machines – II

Theory of three phase induction motors, Principle of operation, slip, phasor diagram, equivalent circuits, expression for torque, maximum torque, starting torque and output power, torque-slip and power-slip characteristics, Circle diagram, Predetermination of characteristics from the circuit diagram, Drawing circle diagram from design parameters and no load and blocked rotor test data, power factor control of three phase induction motor, Starting of Induction motors, Speed control of induction motor, Cogging & Crawling, applications of poly-phase induction motors.

Principle of operation on the basis of double revolving field theory, Equivalent circuit, performance calculations and characteristics, Starting methods, Maximum starting torque conditions in single phase induction motors, Hysteresis motor, Reluctance motor and stepper motor.

Types of Exciters for synchronous machines, flux and MMF phasor diagrams for cylindrical rotor synchronous machines, Armature reaction, open and short circuit characteristics, Leakage reactances, Synchronous reactance, Phasor diagram under loaded conditions, operating characteristics of alternators and their ratings, Predetermination of regulation by EMF and Potier triangle methods for non-salient pole alternators, Steady state power flow equations, Power angle characteristics, Constant excitation and constant power output, Circle diagram for synchronous machines. Two reaction theory for salient pole alternators and pre-determination for regulation, slip test, V curves, Hunting and its suppression, Starting of synchronous motor, Synchronous condenser.

Synchronization of alternators by dark lamp method, Parallel operation of alternators, Alternator on infinite bus bar, Effect of change of excitation and prime mover inputs.