ELECTRIC POWER UTILIZATION AND SAFETY
Academic Year 2025/2026 - Teacher: CRISTINA VENTURAExpected Learning Outcomes
The Course aims to provide knowledge on structures, components, functions, basic analysis, as well as design methods for I Category Electrical Distribution Networks (usually called "Low Voltage", LV, networks), along with several references also to II Category Electrical Distribution Networks (usually called "Medium Voltage", MV, networks.
The latter will be dealt with in depth in the subsequent Course "Smart Grids and Advanced Power Distribution" (Curriculum "Smart Power Systems").
The Course, then, will mainly focus on LV networks and their design according to the CEI (Italian Electrotechnical Committee) Standards concerning Electrical Safety, with some reference to international Standards too.
Note. In the academic year 2025/2026, the course (9 CFU) will be jointly taught by Professor Stefania Conti, who will deliver the lectures covering 7 CFU, and Professor Cristina Ventura, who will conduct practical sessions and laboratory activities covering the remaining 2 CFU.
Course Structure
The teaching includes both lectures and software supported exercises aimed at putting the contents of the theoretical notions into practice and developing the related skills.
Required Prerequisites
Basic knowledge of Electrotechnics, with specific reference to the laws relating to electric and electromagnetic fields, the analysis of radial and meshed electrical circuits in direct and alternating sinusoidal current, in steady state and transient regimes, as well as to the operation of Electrical Power Systems, both single-phase and three-phase systems (symmetrical and balanced or not).
Basic knowledge of the main Electrical Machines (Power Transformers, Synchronous and Asynchronous Machines and Power Electronic Converters) and their operating principles and modelling
Attendance of Lessons
Attendance at the Course is not mandatory but it is strongly recommended, as the Course includes, in addition to theoretical lessons, participatory numerical exercises and group activities, including technical visits.
Detailed Course Content
Note. In the academic year 2025/2026, the course (9 CFU) will be jointly taught by Professor Stefania Conti, who will deliver the lectures covering 7 CFU, and Professor Cristina Ventura, who will conduct practical sessions and laboratory activities covering the remaining 2 CFU.
0. Presentation of the Course and the specific areas of interest with reference to the main functions of the Electric Power System (Generation, Transmission, Distribution and Utilization).
1. Overview of Regulations and Standards for the Electrical Power System; Project documentation for Electrical Installations.
2. Definitions and main classifications related to electrical installations. Review of the fundamental technical choices. Comparison between the use of alternating current and direct current. Neutral grounding in three-phase systems. Phase-to-ground nominal voltages and Categories 0, I, II and III. Classification of the LV distribution systems under study.
3. Evaluation of the "Conventional Load" for both circuits and electrical installations. Conventional Powers and Currents
4. Review of electrical lines’ parameters and equivalent models (electrically “long” and “short” lines).
5. Structure of electrical lines: overhead lines with bare conductors.
6. Structure of electrical lines: cable lines.
7. Electrical sizing and verification criteria for low voltage (LV) and medium voltage (MV) short lines. R-L line model.
8. Overcurrents (Study of Overload and Short-Circuit phenomena).
9. Short-circuit current calculation in radial distribution networks.
10. Switching Devices and phenomenology of the Electric Arc.
11. Protections against overcurrents (classification of different types of Protection Relays and Fuses). Automatic Circuit-Breakers for LV electrical installations.
12. Choice and installation of protection devices against overcurrents according to CEI Standards.
13. Selectivity (discrimination) criteria applied to protections against Overcurrents.
14. Overvoltages and protections.
15. “Electric shock”, effect of the electric current on the human body and Time/Current Hazard Zones. Definition of: Direct and Indirect Contacts, Exposed Conductive Parts (ECP) and extraneous-conductive-part (ExCP).
16 The role of "ground" as an electrical conductor. Earth Electrodes. Ground Potentials. Total Earth Resistance. Total Earth Voltage. Electrical model of the human body. Body Resistance. Earth-body Resistance.
17. Touch Voltages and Source-Touch Voltage. Indirect Contact with and without earthing system. Time-Voltage Safety Limit Curves.
18. Earthing system Structure and electrical connections. Definition of TT, TN and IT.
19. Protection against indirect contacts in TT Systems with supply interruption. The Residual Current Device (RCD) and its functional characteristics. Selectivity between RCDs. Contextualization of the Concept of Extraneous Conductive Part and Equipotential Bonding in TT Systems.
20. Protection Against Indirect Contact in TN Systems and Comparison with TT Systems.
21. Protection against indirect contacts in IT Systems.
22. Protection against indirect contacts without supply interruption.
23. Protection against Direct Contacts.
24. Overview of Technical Requirements for Electrical Installations in ‘Special Locations and Applications’ as Defined by Standard CEI 64-8".
25. Installation of protections and circuit-breakers on phase and neutral conductors in TT, TN and IT Systems.
Textbook Information
1) Technical Publications and Reports written by professionals in the International Electricity Eector (in English).
2) CEI, CENELEC and IEC standards (in Italian and in English).
3) Gaetano Conte, "Manuale di Impianti Elettrici", Ed. HOEPLI (in Italian).
4) Vito Carrescia, "Fondamenti di Sicurezza Elettrica", Ed. TNE (in Italian).
5) Teaching material provided by the professor (in Italian and in English).
Course Planning
| Subjects | Text References | |
|---|---|---|
| 1 | Overview of Regulations and Standards for the Electrical Power System; Project documentation for Electrical Installations. | |
| 2 | Definitions and main classifications related to electrical installations. Review of the fundamental technical choices. Neutral grounding in three-phase systems. Phase-to-ground nominal voltages. Classification of the LV distribution systems. | |
| 3 | Evaluation of the "Conventional Load" for both circuits and electrical installations. | |
| 4 | Review of electrical lines’ parameters and equivalent models (electrically “long” and “short” lines). | |
| 5 | Structure of electrical lines: overhead lines with bare conductors. | |
| 6 | Structure of electrical lines: cable lines. | |
| 7 | Electrical sizing and verification criteria for short lines (R-L model). | |
| 8 | Overcurrents (Study of Overload and Short-Circuit phenomena). | |
| 9 | Short-circuit current calculation in radial distribution networks. | |
| 10 | Switching Devices classification and phenomenology of the Electric Arc. | |
| 11 | Protections against overcurrents (classification of different types of Protection Relays and Fuses). Automatic Circuit-Breakers for LV electrical installations. | |
| 12 | Choice and installation of protection devices against overcurrents according to CEI Standards. | |
| 13 | Selectivity criteria (discrimination) applied to protections against overcurrents. | |
| 14 | Overvoltages and protections. | |
| 15 | “Electric shock”, effect of electric current on human body and the Time/Current Hazard Zones. | |
| 16 | The role of "ground" as an electrical conductor. Earth Electrodes. Ground Potentials. Total Earth Resistance. Total Earth Voltage. Electrical model of the human body. Body Resistance. Earth-body Resistance. | |
| 17 | . Touch Voltages and Source-Touch Voltage. Indirect Contact with and without earthing system. Time-Voltage Safety Limit Curves. | |
| 18 | Earthing system Structure and electrical connections. Definition of TT, TN and IT. | |
| 19 | Protection against indirect contacts in TT Systems with supply interruption. The Residual Current Device (RCD). Selectivity between RCDs. | |
| 20 | Protection against indirect contacts in TN Systems. | |
| 21 | Protection against indirect contacts in IT Systems. | |
| 22 | Protection against indirect contacts without supply interruption. | |
| 23 | Protection against direct contacts. | |
| 24 | Brief overview on CEI Standard technical rules (CEI 64-8) for electrical installations under the so-called “particular environmental conditions". | |
| 25 | Installation of protections and circuit-breakers on phase and neutral conductors in TT, TN and IT Systems. |