Lecturer: Ezio Bassi   Francesco Benzi   Lucia Frosini  

Course name: Devices, systems and diagnostics for industry automation
Course code: 505009
Degree course: Ingegneria Elettrica
Disciplinary field of science: n.d.
L'insegnamento costituisce attività di base per: Ingegneria Elettrica
L'insegnamento è caratterizzante per: Ingegneria Elettrica
The course relates to: Ingegneria Elettrica
University credits: ECTS 9
Course website: n.d.

Specific course objectives

SPECIFIC COURSE OBJECTIVES (DEVICES AND SYSTEMS): The course focuses on a series of arguments related to industrial automation and domotics. SPECIFIC COURSE OBJECTIVES (DIAGNOSTICS): The aim of this course is to introduce the students to the study of the diagnostic systems for the identification of the actual or incipient faults in electrical machines and drives. The diagnostic tools used to detect a fault condition, to identify the damaged element and to determine the cause of fault (mechanical, thermal, electrical or environmental) will be analysed.

Course programme

DEVICES AND SYSTEMS FOR INDUSTRY AUTOMATION
The course aims at giving an overview on various issues in the field of automation both for industrial and civil applications (e.g. robotics & factory automation, home automation) and is mainly centered on communication protocols and electrical drives. The main topics compise:

Automation Systems Architectures; devices for the automation, industrial PLC & PC, systems for Numeric Control; Smart Grids; Levels of Automation; ISO-OSI model; Software for industrial automation; communication protocols (speed, accuracy, determinism) and standards; automation for continuous and discrete industrial processes; domotics and buiding automation: standards and case studies. D.C. four-quadrant chopper and chopper-fed d.c. motor; dead-time on pwm inverters; loads with variable inertia; two-link manipulator: lagrangian formulation and terms of the torque; control of a manipulator with laboratory experiments; control of drives with elastic coupling; harmonic pollution on power lines; double-fed induction motor; schemes and algorithms for the reconstruction of the speed in electrical drives; drives with linear actuators and switched reluctance motors.

DIAGNOSTICS FOR INDUSTRY AUTOMATION
1. Introduction Aim of a diagnostic system: detection, isolation and identification of the fault. Relationship among the diagnostics and the concepts of protection, maintenance, condition monitoring. Reactive, preventive, predictive and proactive maintenance. Reliability, availability, probability density of fault, failure rate, criteria for the classification of the faults. 2. Types of fault in electrical machines and drives and methods for their detection Types of fault: in the stator (windings and core), in the bearings, in the rotor, static and dynamic irregularities of the air-gap, others. Electrical methods: measurement of voltage, current, power, magnetic flux (at the air-gap and leakage), shaft voltage, bearing current, partial discharge. Mechanical methods: measurement of vibration, acoustic noise, force, torque, speed. Other methods: chemical measurements, temperature, etc. Signal analysis in the time and frequency domain. 3. Vibrations in electrical machines and drives Vibration measurement as diagnostic tool. Longitudinal, flexional (Jeffcott rotor) and torsional vibrations. Natural and forced vibrations. Electromagnetic forces: Maxwell tensor, Lorentz forces. Static and dynamic eccentricity. Vibrations in the end-windings. Practical examples. 4. Bearing faults Rolling and friction bearings. Possible damages in the bearing faults and their causes. Methods to detect bearing faults: vibration and stator current analysis. Practical examples. 5. Faults in the stator windings Construction characteristics, possible faults and diagnostic methods for low voltage stator windings (supplied by the grid or by inverter): stator current and leakage flux analysis. Construction characteristics of medium voltage stator windings. Ground insulation failure. Diagnostic methods for medium voltage stator windings: insulation resistance, polarization index, tan-delta or insulation power factor, AC and DC hi-pot test. Partial discharge (PD) measurement: positive or negative polarity of the PD, comparison of the effectiveness of the PD method with respect to the other diagnostic methods, PD detection by measurement of the electric pulses, interpretation of the experimental measurements, PD as direct cause or as symptom, effect of the load and the temperature on the PD. 6. Rotor faults Rotor short circuits in the generators and methods for their detection: measurement of the air-gap flux, recurrent surge oscillation, dynamic impedance. Shaft voltages and currents: methods for their monitoring in turbo-generators and in motors supplied by inverter. Broken rotor bars in induction motors and their detection by stator current, vibration and leakage flux analysis. Inter-bar current phenomenon. 7. Other kinds of faults EL-CID test for stator core faults. Dissolved gas analysis (DGA) for transformer insulating oil.

Course entry requirements

COURSE ENTRY REQUIREMENTS (DEVICES AND SYSTEMS): Basic electrical drives, power electronics, power plants and control. COURSE ENTRY REQUIREMENTS (DIAGNOSTICS): Knowledge of the functional and construction aspects of the electrical machines and drives.

Course structure and teaching

Lectures (hours/year in lecture theatre): 68
Practical class (hours/year in lecture theatre): 0
Practicals / Workshops (hours/year in lecture theatre): 0

Suggested reading materials

SUGGESTED READING MATERIALS (DEVICES AND SYSTEMS): Quaderno tecnico GISI. Bus di campo tra normativa e tecnologia. GISI Milano, 2000. P. Vas. Parameter Estimation, Condition Monitoring, and Diagnosis of Electrical Machines. Oxford University Press, 1993. Daniele Fabrizi. Enciclopedia-Vocabolario dell'Automazione Industriale. Edizioni CEI. 2002. E. Bassi - F. Benzi. Lecture Notes. Available only on a few arguments. SUGGESTED READING MATERIALS (DIAGNOSTICS): Notes prepared by the lecture and sent to the students by mailing list. To study in depth, the following books can be consulted: Peter Tavner, Li Ran, Jim Penman and Howard Sedding: Condition Monitoring of Rotating Electrical Machines, 2nd Edition, IET, 2008. Stone G., Boulter E.A., Culbert I., Dhirani H.: Electrical Insulation for Rotating Machines: Design, Evaluation, Aging, Testing, and Repair, Wiley-IEEE Press, 2004. Geoff Klempner, Isidor Kerszenbaum: Handbook of Large Turbo-Generators. Operation and Maintenance, Wiley-IEEE Press, 2008.

Testing and exams

TESTING AND EXAMS (DEVICES AND SYSTEMS): The exam does comprise a written test on fieldbusses, domotics & building automation and an oral presentation (power point accompanied by a written relation, duration: 35-40 minutes) on a subject related to electrical drives. TESTING AND EXAMS (DIAGNOSTICS): The exam consists of an oral test on the contents of the course.