LEARNING OUTCOMES

Provide elements on the electrical equipment construction for low and high voltage applications. Provide the elements for diagnostics and maintenance of electromechanical components.

AIMS AND LEARNING OUTCOMES

At the end of the course the student is expected:

• to understand the theoretical principles of AC electrical machines
• to understand the theoretical principles of power electronic inverters
• to solve problems related to the operation of electrical machines
• to solve problems related to the operation of power electronic inverters

Furthermore the student is expected to learn the principles of the maintenance of electrical equipment by predictive diagnostics techniques for early detection of failure conditions. In particular, proactive and predictive maintenance through measurements related to insulation systems and specifically by partial discharge measurements. The student is also expected to understand the Implementation of digital measurement techniques for the acquisition of PD Pattern and the use of static analysis of acquired data for the morphological identification of defects.

PREREQUISITES

The student expected background to fully understand the content of the course is related to the basics of electric circuits, especially three phase AC systems and electromagnetism

For the part relevant to the diagnostic basic functional and constructive knowledge of electrical machines.

TEACHING METHODS

For the Electrical Machines part 24 hours of heoretical lectures in class and practical exercises during the lectures.

For the maintenance part 18 hours of classroom teaching and 6 hours of laboratory activities

Working students and students with certified SLD (Specific Learning Disorders), disability or other special educational needs are advised to contact the teacher at the beginning of the course to agree on teaching and examination arrangements so to take into account individual learning patterns, while respecting the teaching objectives.

SYLLABUS/CONTENT

The course will cover the following topics:

Fundamentals of AC electrical machines employed in shipboard systems:

• Electromechanical energy conversion
• Transformers
• Synchronous machines
• Asynchronous machines
• Basics of machine losses

Power electronics for drive systems

• Basics of power devices and gate driver circuits
• Three phase converter and its application to drive systems
• Inverter deadtimes
• Basics of inverter losses

Insulating systems and insulating materials. Ageing. Proactive, preventive and predictive maintenance. Types of failure of transformers and rotating machines. Fault analysis and Ishikawa diagrams. Examples of detailed Ishikawa diagrams for different types of rotating machine failure. Conventional offline diagnostic techniques on insulation systems. Mechanical and electrical measures for bearing diagnostics in rotating machines. Online and offline diagnostic techniques related to stator and rotor windings of synchronous and asynchronous machines. Online and offline diagnostic techniques related to insulating systems of oil and cast resins transformers. The phenomenon of partial discharges. Measurement of partial discharges as a diagnostic tool for predictive maintenance. Low and high frequency partial discharge measurement systems for conducted and irradiated signals. Integration into the time and frequency domain. Design of the measurement impedance for quasi-integration. Analog and digital PD measurement systems. Analog signal analysis for defect detection. Data analysis in digital measurement systems. Statistical outlines. Data processing for defect detection with digital measuring systems. Defect classification and degree of hazard. Measurement systems in the case of inverter power supplies.

RECOMMENDED READING/BIBLIOGRAPHY

• Krause, P. C., Wasynczuk, O., Sudhoff, S. D., & Pekarek, S. (2013). Analysis of electric machinery and drive systems
• Fitzgerald, A. E., Kingsley, C., Umans, S. D., & James, B. (2003). Electric machinery
• Mohan, N., Undeland, T. M., & Robbins, W. P. (2003). Power electronics: converters, applications, and design

Notes of the Course

Electrical Insulation for Rotating Machines, Greg C. Stone et alt, IEEE PRESS

IEC standards