Electric Machines

Recommended Prerequisites

Electrical Energy Conversion

Teaching Methods

Theoretical lectures in the black board and with the aid of Powerpoint slides for the presentation of the concepts, principles and fundamental theories about the topics covered in the curricular unit. Theoretical-practical classes to solve problems and exercises that illustrate the application of the theoretical concepts to real cases in the engineering world. In these classes, some simulations in Matlab/Simulink environment are performed to simulate the behaviour of the systems under study. Laboratory classes to validate the theoretical and practical concepts addressed in the curricular unit.

Learning Outcomes

It is intended that students acquire skills in the following topics: (i) three-phase power transformers, autotransformer and measurement transformers; (ii) design of windings for ac machines; (iii) synchronous and asynchronous machines: design and main construction aspects; steady-state operation and performance.

Work Placement(s)

No

Syllabus

Three-phase transformers: core types; equivalent circuit, no-load and short-circuit tests; magnetic saturation; excitation current; vector group; parallel operation of transformers; tertiary winding. Autotransformers. Voltage and current transformers. Cooling system of power transformers.

Windings of ac machines. Distribution of the magnetomotive force and induced voltages.

Asynchronous machines: types of rotor; modes of operation; characteristics in steady-state. Service classes and service factor. Insulation classes.

Synchronous machines with field winding and permanent magnets in the rotor: equivalent circuit; voltage phasor diagram; no-load and short-circuit characteristics; PQ diagram; parallel operation with the grid; starting methods of synchronous motors.

Head Lecturer(s)

Sérgio Manuel Ângelo da Cruz

Assessment Methods

Assessment
Laboratory work reports: 20.0%
Project: 25.0%
Exam: 55.0%

Bibliography

D. Kothari, I. Nagrath: “Electric Machines”, Tata McGraw-Hill, New Delhi, 2010.

S. Chapman: “Electric Machinery Fundamentals”, 5th edition, McGraw-Hill, New York, 2012.

J. A. Melkebeek, "Electrical Machines and Drives - Fundamentals and Advanced Modelling", Springer, 2018.