70/0053-M - ELECTROTECHNICS
Academic Year 2016/2017
Free text for the University
BARBARA CANNAS (Tit.)
- Teaching style
- Lingua Insegnamento
|[70/77] CHEMICAL ENGINEERING||[77/00 - Ord. 2015] PERCORSO COMUNE||6||60|
|[70/78] MECHANICAL ENGINEERING||[78/00 - Ord. 2011] PERCORSO COMUNE||6||60|
The basic objective of this course is to introduce students not specialists in the field to the fundamental electric circuit theory and its core applications. The students will acquire basic knowledge and skills necessary for the analysis of electrical circuits in steady state and sinusoidal steady state, single phase and three phase.
basic elements concerning the principle of operation and the circuit model of the transformer and the induction motor shall also be provided.
Knowledge and understanding
Knowing and understanding the behavior of steady state and sinusoidal steady-state electrical circuits single phase and three phase, and the methods of analysis. Knowing and understanding the problem of the power factor correction of electrical loads. Knowing the operating principle and constructive characteristics of the transformer. Knowing the principle of operation of the asynchronous motor and the problems related to the starting and speed control. Understand the equivalent circuits describing the electromagnetic behavior of the transformer and of the asynchronous motor.
Applying knowledge and understanding
Choose and apply the most suitable methods of analysis for electrical circuits in steady state and sinusoidal, steady state, single phase and three phase; be able to size the capacitor banks for the power factor correction, choose a transformer, determine the parameters of the equivalent circuit from the transformer data plate.
Ability to communicate with technical terms proper of the electrical engineering, ability to use graphical representations for the description of electrical circuits, transformers or asynchronous motors. Ability to describe, in both oral and written formats, the goals, the process and the results of the adopted procedures.
Having the ability to correctly interpret and verify the obtained results.
Lifelong learning skills
Be able to apply their knowledge to different contexts from those presented during the course, and deepen the topics using materials other than those proposed as the IEC standards or technical texts.
Knowledge of the basic topics of the following courses: Calculus I, Calculus II, Physics I, Physics II, Geometry and Algebra.
Systems of units
Charge and Current
Power and Energy
Passive and active sign convention
Nodes, Branches, and Loops
Equivalences: Delta to Wye and Wye to Delta Conversion, Series resistors and Voltage division, Parallel resistors and Current division
Thevenin’s and Norton’s Theorems
Maximum Power Transfer
Network Analysis: Nodal analysis and Mesh analysis
AC Steady State analysis:
Representations of sinusoidal signals as a function of time, complex and phasor representation
The symbolic method
Network components and their constitutive equations: Resistor, Capacitor, Inductor, Operational amplifier, Sources
Impedance and admittance
Instantaneous Average and Reactive power, Complex power, Apparent power
Tellegen’s theorem and Boucherot theorem
Maximum Average Power Transfer
Steady state network analysis: Nodal analysis and Mesh analysis.
Thevenin's and Norton’s theorem.
Conservation of AC power
Power Factor Correction
Magnetic fields in vacuum: Biot–Savart law, Ampère's law, Magnetic flux, self-inductance and mutual inductance.
Electromagnetic induction: Lenz’s Law, Induced electromotive force (emf) and Magnetic forces on moving charges.
Magnetic fields in materials: magnetic properties of materials (Diamagnetism, Paramagnetism, Ferromagnetism), Magnetic energy and Hysteresis loop, Hysteresis losses, eddy current losses.
Ideal coupling and ideal transformer
Non ideal coupling
Coupled circuits and simplified model
Magnetically coupled circuits through iron core and simplified model.
Components of a transformer: nucleus, cooling systems.
The real transformer
The rotating magnetic field
Constructive characteristics: rotor and stator
Equivalent network and phasor diagram
Energy balance and efficiency
Torque and torque-speed relationship
40 lecture hours
20 hours of exercises and electrical circuits laboratory
Lessons are mainly held in the traditional way through the use of the blackboard, with the support of Power Point slides made available to students. The exercises of analysis of electrical networks are solved by the teacher and / or the students.
Two examination simulations will be performed before the mid-term tests.
Verification of learning
The assessment of learning outcomes attainment is performed through a written test and an oral interview. The score will also consider the quality of oral and written communication. The written test, aimed at evaluating firstly the operational capabilities, provides for the solution of one or more problems related to the analysis of power grids, magnetic circuits, transformers, asynchronous motors.
The test score is out of thirty, weighting the rating attributed to the different exercises according to the commitment required for their resolution. During the test it won’t be allowed to use only the scientific calculator, whereas it won’t be allowed the use of texts of any kind, mobile phones, tablets and computers. It won’t be allowed to candidates, to communicate with each other or with other people.
Students who pass the written test can access the oral test, in which the written report will be discussed and the degree of theoretical knowledge (electrical components, theorems for network analysis, principles of operation of the transformer and the induction motor, equivalent schemes) will be determined. Moreover, the communication skills of the student will be tested.
There will also be two written tests during the year consistent in solving a series of exercises on different parts of the course program and in the oral discussion of test. Partial exams are reserved for students attending the lessons.
The text of the exams is available on the teacher web site.
•R. Perfetti "Circuiti elettrici" Zanichelli;
•G. Fabricatore “Elettrotecnica e Applicazioni” Liguori, Napoli; (per il trasformatore edio motore asincrono)
•G.Rizzoni “Elettrotecnica, Principi e Applicazioni” McGraw-Hill.
Attendance is not mandatory but highly recommended, as well as the systematic study of the program carried out during lectures, the critical analysis of the exercises in the classroom and the personal resolution of additional exercises (found in the recommended texts). During the course will be provided with copies of the slides used in class.