Instrumentation Tecniques
Code
7474
Academic unit
Faculdade de Ciências e Tecnologia
Department
Departamento de Ciências dos Materiais
Credits
6.0
Teacher in charge
Rodrigo Ferrão de Paiva Martins
Weekly hours
5
Total hours
100
Teaching language
Português
Objectives
The discipline of Instrumentation intends to develop knowledge in circuit analysis and a overview about the different instruments used to measure quantities whose process is based in transforming the signal associated to a given quanity into an electrical signal. In this sense, it is essential that students know how to analyze passive and active electrical circuits, in steady state and transient conditions, respectively. In addition, it is important that students know the symbols to be used.
In terms of meters, it is important that students know how the digital and analog gauges and what distinguishes them. In addition, the students should know what kind of signal transducers exist and how they interact with the quantities to be measured.
Finally it is intended to provide an overview of the measurement systems and their necessity in the vast field of Control Engineering and Testing.
Prerequisites
Obtain knowledge of basic mathematical analysis and Physics.
Subject matter
1. Basic Components and Electric Circuits
Electrical quantities and units: charge, current, voltage and power. The current direction and polarity of the voltage. Ideal sources of voltage and current. Dependent sources. Resistance and Ohm''''''''''''''''s Law.
2. Currents and Voltages Laws
Notions of nodes, branches and loops. Kirchhoff laws (KCL and KVL). Circuit analysis in series and parallel. Parallel and series combination of sources. Voltage and current divider.
Measuring instruments. Errors in instrumentation. DC meters. Potentiometric circuit. d''''Arsonval meter, voltmeter, ammeter to ohmmeter, sensitivity of the measuring instruments, internal resistance and load resistance.
3. Circuit Analysis Techniques
Superposition.Thevenin and Norton theorems. Maximum power transfer.
Resistance measurements: Wheatstone bridge. Half-bridge circuits and quarter bridge. Kelvin Bridge.
4. Bipolar Transistores (BJT) - Introduction
Bipolar transistors (BJT) in DC.
The ideal model. Applications: voltage follower. Non-inverting and inverting amplifier. voltage adder.
Instrumentation Amplifier. Amplifying the signal from a Wheatstone bridge. Current-voltage converter.
6. Capacitors and Inductors
Voltage-current relation in an ideal capacitor. Current-voltage relationship in an ideal inductor. Calculation of energy stored in capacitors and inductors. Analysis of the temporal response of capacitors and inductors. Combinations of series and parallel capacitors and inductors. Time constant in RC and RL circuits.
Circuits for differentiators and integrators.
Natural and forced response of circuits. RLC circuit. The resonance frequency and damping factor in series and parallel for RLC circuit. Critical damping and sub critical damping.
7. Sinusoidal analysis
Characteristics of sinusoidal functions. Representation as phasor. Conversion between the time domain and frequency. Impedance and Admittance. Combination of series and parallel in the frequency domain. Application of techniques in the frequency domain analysis of circuits.
Use d''''Arsonval meter for measuring AC signals. Rectifiers. AC Bridges: balancing an impedance bridge, Wien Bridge, Maxwell Bridge, Schering Bridge.
Instantaneous power, average power. Quadratic average value. Reactive power. Relationship between the complex power, average and reactive. Power factor and load.
8. Apparatus and measurement techniques
Digital multimeter, oscilloscope, electrometer, lock-in.
9. Transducers (Introduction)
Classification of transducers. Position transducers (resistive), deformation (strain), capacitive, inductive, piezoelectric, temperature, ultrasonic, photoelectric.
Bibliography
- Extended abstracts organized by Rodrigo Martins and their attached bibliography
- Fundamentals of Electric Circuits, Charles K. Alexander, Matthew Sadiku, MacGraw-Hill, 2004
- The Art of Electronics, Paul Horowitz, Winfield Hill, Cambridge University Press 2001
- Electronic Instruments and Measurements, Larry Jones, Foster Chin, Prentice-Hall.
Teaching method
The teaching method is based on three types of lessons: Lectures, present registered for statistical purposes and positive discrimination (recovery point value between 0.5 to 1 for those who participate in 100% or 90% of classes); evaluation proceeds from theoretical component through resolution of issues, to be held in the classroom after their exposure or as student tutorial work, a set for large area taught. Are expected 8 large sets, of which 4 are kind of inquiry answer true or false; the problem solving session and compulsory laboratory sessions, whose no presence determines the exclusion from final exam.
Evaluation method
For obtaining frequency, students must be use (note 9.5) the practical component (MA1 and MA2-see below) and have conducted all Laboratory work. The non-performance of any of the moments of evaluation 1 or 2 excludes students the possibility to obtain frequency.
Evaluation
1. Realization of mini-reports of group assigments
2.MA2-individual Discussion (theoretical and practical) on the mini-reports.
3.MA3 and MA4-Two written tests.
4.AS-summative evaluation (presence and participation of the students in class).5
5. AC-continuous evaluation of the theoretical component, translated in questions given to the student to be solved. Students with positive tutorial assessment are exempted from the theoretical component of the tests. For the first test count tutorials until the first assessments and for the second test, evaluations tutorials taking place between the first and second test. Students who do not comply with these conditions will have to perform the tests the averages are obtained according to ass forms that follow:
The final grade is calculated as follows:
NT (note the tests) =(MA3+MA4)/ 2 rounded to tenths
NF= 0,4*NT+ 0.17*AC0, 25*MA1+0, 20*MA20 +0.03AS
If the presence of the pupil to the set of classes is less than 60 the number of the classes will be zero.
For students with frequency:
NF =0, 40*NT+0.17*AC+0, 40*note of frequency +0.03*AS
NOTE: to be aproved requires to have at least a value above 8.5 in one of the intermediate process evaluation and the final avreage score has to be above 9.5 out of 20 marks.
Final Examination
The students can go directly to final exams. The final score is calculated using the equations:
students without frequency:
NF = 0,55*nota de exame + 0,25*MA1+0,2*MA2
Students with frequency:
NF = 0,55*nota de exame + 0,45*nota de frequência
In both cases the final score to be approved must be above 9.5 out of 20 marks
.