ELECTRICAL MEASUREMENTS AND SAFETY
The course aims to provide the basic concepts related to metrology and power quality problems as well as tools needed to analyze the problems of electrical safety.
1.Knowledge and understanding
The student must know:
-the general criteria of measurement and evaluation of power quality disturbances
-the laws on the electrical safety.
-the general criteria for designing the protections against overcurrent and against direct and indirect contacts.
2.Applying knowledge and understanding
The student must demonstrate to be able
-to integrate knowledge in the field of power quality disturbances and electrical power systems.
-to apply the criteria for the selection and use of protective installation against electrical risk.
The student must demonstrate that he has the basic knowledge for dealing and deepening in an autonomous way the issues related to the power quality and electrical safety problems.
The student must demonstrate the ability to easily explain to people
- the methodologies for the evaluation and reduction of the power quality disturbances
- the solutions adopted in the electrical distribution systems for the achievement of prefixed safety levels.
The student must be able to update information about power quality and electrical safety problems through texts, standards and publications in order to acquire the ability to undertake further courses, specialized seminars and master
The student must have acquired the following knowledge provided by the courses of "Electrical circuits and Network Analysis" and "Electrical power systems":
The circuit model: ideal circuit elements, voltage and current. Kirchhoff’s laws. Linear resistive circuits: series and parallel equivalence, superposition principle, Thevénin-Norton’s theorem. Linear circuits in DC and AC steady state. Complex power, active power, reactive power, and conservation properties. Dynamical circuits, general methods of solution. Symmetric three-phase circuits: balanced, unbalanced.
Normal and abnormal operating conditions of an electrical power system; overcurrent and over voltage protection systems
Electrical safetyIntroduction on Electrical safety (0.5 CFU - 4 hours)Definition of security and risk. Security of a system. Reliability and security. The acceptable level of security. The legislative bases of security (0.5 CFU - 4 hours)CEI Standards. The DM 37/08. Overload protection devices (0.75 CFU - 6 hours)Current rating of the cableOverload capability curve of a cableTime-current characteristic curves of protection devicesCircuit breakersFusesRequirements for the overload protection deviceShort-circuit protection devices (0.75 CFU - 6 hours)Recalls on the short-circuit currentThermal stress on a cable in short circuit conditionsShort circuit current calculationRequirements for the short-circuit protection deviceFuses and Circuit breakersEffect of current on the human body (1.25 CFU - 10 hours)Introduction to electrical shock Limits of the electric currentElectrical resistance of the human bodyThe earth resistanceResistance to earth of a personFull voltage and touch voltage.Protection against direct contact (0.25 CFU - 2 hours)Total and partial protection measuresTT system - Protection against indirect contact (1.0 CFU - 8 hours)Protection by means of maximum current devicesLimits of maximum current protectionProtection by means of a differential circuit breakerSelective Coordination Earthing system (0.25 CFU - 2 hours)Components and technical specificationsTN system - Protection against indirect contact (0.5 CFU – 4 hours)Equivalent circuitDistribution circuits and terminalsDifferential circuit breakersSizing of the Earthing Resistance of HV/MV Transformer Testing and inspection (0.5 CFU – 4 hours)DPR 462Measuring Earth Resistance Test of differential circuit breaker
Definitions and basic concepts of measurement. Measurement uncertainty. (1.0 ECTS)
Signals classification; analog-to-digital conversion. (0.5 ECTS)
Power quality disturbances. (0.5 ECTS)
Harmonics: definitions, evaluation methods, indices and objectives. (1.5 ECTS)
Solutions for harmonic distortions reduction. (0.5 ECTS)
Interruptions: definitions, methods, indices and objectives. (1.0 ECTS)
Voltage dips: definitions, methods, indices and objectives. (0.5 ECTS)
Solutions to limit the effects of voltage sags and interruptions. (0.5 ECTS)
This part of the course introduces the principles of electrical safety and provides useful knowledge for the choice of protection systems against overcurrents and against contacts with an electric circuit.
Electrical safety Introduction on Electrical safety (0.5 CFU - 4 hours) Definition of security and risk. Security of a system. Reliability and security. The acceptable level of security. The legislative bases of security (0.5 CFU - 4 hours)CEI Standards. The DM 37/08. Overload protection devices (0.75 CFU - 6 hours)Current rating of the cable Overload capability curve of a cable Time-current characteristic curves of protection devices Circuit breakersFuses Requirements for the overload protection device Short-circuit protection devices (0.75 CFU - 6 hours) Recalls on the short-circuit current Thermal stress on a cable in short circuit conditions Short circuit current calculation Requirements for the short-circuit protection device Fuses and Circuit breakers Effect of current on the human body (1.25 CFU - 10 hours) Introduction to electrical shock Limits of the electric current Electrical resistance of the human body The earth resistance Resistance to earth of a person Full voltage and touch voltage. Protection against direct contact (0.25 CFU - 2 hours)Total and partial protection measures TT system - Protection against indirect contact (1.0 CFU - 8 hours)Protection by means of maximum current devices Limits of maximum current protection Protection by means of a differential circuit breaker Selective Coordination Earthing system (0.25 CFU - 2 hours) Components and technical specifications TN system - Protection against indirect contact (0.5 CFU – 4 hours) Equivalent circuit Distribution circuits and terminals Differential circuit breakers Sizing of the Earthing Resistance of HV/MV Transformer Testing and inspection (0.5 CFU – 4 hours)DPR 462 Measuring Earth Resistance Test of differential circuit breaker
Lectures, classroom exercises
Caramia, P., Carpinelli, G. and Verde, P. Power Quality Indices in Liberalized Markets, John Wiley & Sons, Ltd, Chichester, UK, 2009
V. Carrescia, Fondamenti di sicurezza elettrica, TNE, Torino.
Peter E. Sutherland: Principles of Electrical Safety, John Wiley & Sons
Notes provided by the teacher
The exam consists in an oral test in which the level of knowledge of the topics addressed during the course will be assessed.The exam typically involves two questions, one of which on the choice of protection systems against over-currents and one on the choice of protection systems against electrical contacts.The oral exam has a total duration of approximately 30 minutes.The final grade is the average of the grades obtained by the student for two questions.
No additional information