Class Electrical Machines I

This unit is oriented to the study, analysis and dimensioning of the main electromagnetic machines present in the daily life of today's society in its most diverse environments.

• Introduction to Electric Machines:
  • Reviews on electromagnetism.
  • Introduction to magnetic circuits.
  • Inductance concept.
  • Magnetic properties of materials.
  • Magnetic circuits with sinusoidal excitation.
• Electrical Transformer (T):
  • Shared magnetic fields and circuits with magnetic coupling.
  • Ideal (T).
  • Transformation of electrical circuit elements.
  • (T) equivalent circuit.
  • AMR
  • Determination of the (T) parameters.
  • Nominal capacity.
  • (T) under load: Voltage regulation, efficiency.
  • "Per unit" values.
  • (T) for poly-phase systems.
  • Autotransformers,
  • Measurement (T).
• Direct current machine:
  • Magnetic system.
  • Windings, commutator, brushes.
  • Torque and induced voltage.
  • Reversibility.
  • Equivalent circuit.
  • Shunt, series and compound configurations.
  • Binary-speed characteristic.
  • AMR, switching and auxiliary poles.
  • Power balance.

4hr classroom lessons are distributed as follows: 1.5hrs of theoretical lectures - expository purpose; 1.5hrs of practical classes - practical problems solving; 1h of laboratory - demonstration and experimental validation.

2 modalities of assessment (As):

Continuous (As) - two written tests during the lecturing period, each contributing to 35% of the final (As); Assessment obtained at the laboratorial component, with a weight of 30%. The approval is only possible if the average of the two written tests is greater than or equal to 10 values.

(As) by exam (ex). Written test that covers all the contents, contributing to 70% of the final assessment. Also a laboratory test will performed, contributing to 30% of the final grade.

The (ex) is governed by the general assessment directives, being the students subscription mandatory.

Note: The described assessments can be rectified according to the results of an extraordinary oral exam that students must attend when summoned by the professor.

• Marques, H. S. (2021), Apontamentos de Máquinas Eléctricas I. Lisboa: ULHT
• Slides da unidade curricular de Máquinas Eléctricas I