1) A.E. Fitzgerald, C. Kingsley, and A. Kusko, " Electric Machinery", New York: McGraw-Hill Book Company, 1971.
2) L.W. Matsch and J.D. Morgan: Electromagnetic and Electromechanical Machines, New York: John Wiley & Sons, 1987.
3) S. Crepaz, "Macchine Elettriche", CittàStudi, 1997
Learning Objectives
Knowledge and ability to understand:
1) Electromagnetism laws, AC single-phase, two-phase and three-phase circuits and DC circuits both in transient and steady-state behavior.
2) Operating principles, electromagnetic and mechanical behaviors of the main static and rotating electrical machines: transformers, AC motors and generators, DC motors and generators.
3) Methods to test the electrical machines.
Ability to apply knowledge in order to derive the mathematical models of the electrical machines in the different operating conditions.
Ability to apply knowledge in order to define the equivalent circuits parameters and the operating conditions of the electrical machines.
Ability to apply knowledge in order to select the electrical machines for different applications on the basis of the electrical requirements.
Prerequisites
Good understanding of steady-state and transient analysis techniques of single-phase and three-phase circuits.
Teaching Methods
Lectures supported by ìprojector, laboratory team-works, personalized feedback and coaching to improve every aspect of the student's work.
Further information
At the end of the course a successful student should have developed a good ability to choose transformers, generators and motors for industrial applications, should know the testing procedures of the electrical machines in order to determine the principal characteristics.
Type of Assessment
Intermediate tests just for students attending the course; Oral exam based on theoretical questions oriented to assess:
- knowledge of the operating principles, electromagnetic and mechanical behaviors of the main static and rotating electrical machines: transformers, AC motors and generators, DC motors and generators.
- knowledge of the methods to test the electrical machines.
- ability to apply knowledge in order to derive the mathematical models of the electrical machines in the different operating conditions.
- ability to apply knowledge in order to define the equivalent circuits parameters and the operating conditions of the electrical machines.
- ability to apply knowledge in order to select the electrical machines for different applications on the basis of the electrical requirements.
Course program
1) Preliminary part:
Electromechanical energy conversion. Analysis of two-pahse and three-phase circuits. Power of two-phase and three-phase circuits.
AC circuit relationships.
2) Transformer:
Two-winding transformer. Core loss current, magnetising current. Leakage reactance. Linear equivalent circuit. Phasor diagrams. Voltage drop. Three-phase transformer connections. Open-circuit and short-circuit tests. Determination of equivalent circuit parameters. Efficiency. Auto-transformers. Instrument transformers.
3) Synchronous machine:
Cylindrical-rotor synchronous machine. Representation of airgap m.m.f. waves. Phase inductances. Mutual inductances. Vector equation of cylindrical-rotor synchronous machine. Magnetizing inductance. Synchronous inductance. Phasor equation. Steady-state equivalent circuit. Rotating magnetic fields. Vector and phasor diagram of cylindrical-rotor synchronous generator. Torque, power versus angle characteristic. Open-circuit, short-circuit, and zero power-factor tests. Potier triangle. Saturated reactances. Salient-pole machine.
4) Asynchronous machine:
Wound rotors and squirrel cage rotors. Vector equations of asynchronous machine, slip frequency. Magnetizing inductance. Steady-state equivalent circuit. Slip-torque relationship. No-load and locked rotor tests. Determination of equivalent-circuit parameters. Efficiency. Starting and braking, speed control. Variable-voltage, variable-frequency control. Brief overview about single-phase induction motors.
5) Direct-current machine:
Armature windings, field excitation, armature reaction. Interpoles, compensating winding. Separately excited machine, shunt machine, series machine, compound machine. Load characteristics of generators. Speed-torque characteristics of motors. Motor starting and braking, speed control. Variable-voltage speed control.