78566 - Design and Diagnostics of Electrical Insulation Systems M

Learning outcomes

The course aims to provide in-depth knowledge on the use of the main solid, liquid and gaseous electrical insulators in the components of medium and high voltage electrical power systems. At the end of the course the student is able to design and qualify the electrical insulating systems in DC and AC, e.g. high voltage cables, isolators, rotating machines, transformers and GIS. He is also able to apply the main diagnostic techniques to evaluate the aging state of the above-mentioned insulating systems.

Course contents

1) Recall on the main solids, liquids and gasses

2) Conduction mechanisms in insulations

3) Electric response of a dielectric

4) Aging and breakdown of insulators

4.1) Partial discharges

5) Life models for single, combined, phenomenological and probabilistic stresses.

6) Design criteria for HVAC and HVDC electrical insulation systems
6.1) HVAC and HVDC cables
6.2) Field grading
6.3) Capacitors
6.4) Bushings

7) Health index: main diagnostic techniques for assessing the status of electrical components.

Readings/Bibliography

There is no single textbook.

The slides projected in the classroom and available on IOL are sufficient

Texts recommended for further study and review:

• E. Kuffel, W.S. Zaengl and J. Kuffel, High Voltage Engineering: Fundamentals. Newnes, 2000
• D. Kind, H. Kamer, High-Voltage Insulation Thchnology, Springer, 1985
• L. Dissado, J. Fothergill, Polymers Electrical Degradation and Breakdown, Peter Peregrinus, 1992, UK
• L. Simoni, Strength and resistance of aging systems, Aracne editrice, 2007
• G. Mazzanti, M. Marzinotto, Extruded Cables for High-Voltage Direct-Current Transmission: Advances in Research and Development, Wiley-IEEE Press, 2013

Teaching methods

The course consists of front lessons, computer and laboratory exercises.

Assessment methods

The exam for attending students can be divided into two partial tests on half the program: an intermediate test, approximately halfway through the course, and a final test, immediately after the end of the course. The mid-term exam is written while part of the final exam could be oral.

Both tests, lasting a maximum of two hours each, consist of 10 open-ended questions and / or exercises on the topics relating to the parts of the program covered by the test itself. Eight of these questions require short and targeted answers while the remaining two require a broader and more articulate answer, possibly even oral if required by the test.

Each test is assigned a maximum score of 32; sufficiency is achieved with a score of 18. An insufficiency or absence from the first partial test precludes the possibility of taking the second. The final mark, out of thirty, is obtained from the arithmetic average of the marks of the two tests rounded to the nearest integer. Honors can be awarded if the final score is ≥ 31. Once the final grade is known, the student must decide whether to accept or reject the grade before the deadline communicated by the teacher.

The refusal of the grade, insufficiency, or absence in one or both partial tests involves the repetition of the exam in a single session on the whole program.

All sessions following the final partial exam will take place over the entire program in a single session in the same way as the partial tests described above.

Passing the exam will be guaranteed to students who demonstrate mastery and operational ability in relation to the key concepts illustrated in the teaching, and in particular to the phenomena of conduction and polarization in insulating materials, aging, diagnostics and design of HV cables, bushing, capacitors and field graders.

A higher score will be awarded to students who demonstrate that they understand and are able to use all the teaching contents, illustrating them with language skills, solving even complex problems and showing good operational skills.

Failure to pass the exam may be due to insufficient knowledge of the key concepts, in particular relating to the sizing and diagnostic methodologies of electrical insulating systems, as well as the lack of mastery of technical language.

If the final grade is less than 18/30 the student will be rejected and will not be able to take a new test before 15 days.

The student has the right to reject a positive grade assigned by the teacher a maximum of two times.

Teaching tools

Copy of the slides displayed at lectures will be provided to the students on "virtuale.unibo.it". Look at the link on didactic material.

The course will make use also of Matlab programs for design of HVAC, HVDC cables and bushing.

Office hours

See the website of Davide Fabiani