Magnetic hysteresis: B-H curve and B-H loop with DC excitation
Magnetic hysteresis with AC excitation
Magnetic circuit: Series and parallel circuit with air gaps
Faraday's laws of electromagnetic induction: Statically induced EMF and dynamically induced EMF
Force on current carrying conductor
Transformer (14 hours)
Transformer parts and their functions
Transformer types: Core and shell types
Working principle and EMF equation
Ideal and practical transformer
Mutual inductance and coupled circuit model
No load and load operation, equivalent circuits and phasor diagrams
Transformation of impedances, voltage regulation
Capacity of transformers
Exciting current harmonics
Transformer inrush current
Losses and efficiency of 1-phase transformer, all day efficiency
Tests: Polarity test, open circuit test, short circuit test, Sumpner's test
Instrument transformers: Potential transformer (PT) and current transformer (CT) and their applications
Auto transformer: Construction, working principle and Cu saving
Three phase transformers: Introduction, types of connections, Scott-T connection
Introduction of three winding transformer
Parallel operation of transformer: 1-phase and 3-phase
DC Generator (8 hours)
Introduction of DC machine and its construction
Armature windings (lap and wave winding)
Working principle, commutator action, EMF equation
Method of excitation: Separately and self-excited, types of DC generator
Characteristics of series, shunt and compound generator, and applications
Voltage build up process
Armature reaction
Commutation: Interpoles and compensating windings
Losses, efficiency and voltage regulation
DC Motors (7 hours)
Working principle, back EMF and torque equation
Types of DC motor, characteristics of DC motors and their applications
Losses and efficiency
Starting of DC motors: 3 point and 4 point starters for shunt motor
Speed control of DC motor: Series, shunt, and reversing the direction of rotation
Testing of DC machine: Retardation test and Swinburne's test for shunt motor
Three-Phase Induction Machines (12 hours)
Three phase induction motor: introduction, constructional details, rotor types (squirrel cage and phase wound)
Operating principle: Rotating magnetic field, synchronous speed, slip
Analysis of standstill condition: Equivalent circuit, starting torque equation
Analysis of running condition: Equivalent circuit, running torque equation
Torque-slip characteristics and effect of rotor resistance
Power stages in three phase induction motor, losses and efficiency
Testing of three phase induction motor: No-load test and Block rotor test
Methods of starting: Direct on-line method, primary resistor method, auto-transformer starter, star-delta starter, rotor rheostat starter
Speed control methods: Primary voltage control, frequency control, cascade connection and rotor rheostat method
Three phase induction generator: operating principle, T-S characteristic for generating mode, requirements of excitation capacitor, voltage build-up process
Induction generator operation: Isolated and grid connected
Practicals
Magnetic circuits: Draw B-H curve for two different samples of iron core and compare their relative permeabilities
Two winding transformers: Perform turn ratio test, open circuit and short circuit test, determine regulation and efficiency at full load and examine exciting current waveform and harmonics
DC generator: Draw open circuit characteristic of a DC shunt generator and calculate maximum voltage built up, critical resistance, critical speed and load characteristic of shunt generator
DC motor: Perform speed control of DC shunt motor by armature control method and field control method and draw Torque-Speed characteristic curve
Three phase induction motor: Perform the no-load test and blocked rotor test, draw torque-slip characteristics and observe the effect of rotor resistance on torque-speed characteristics
