Calibration Methods For Reproducible And Comparable Electromagnetic Partial Discharge Measurements In Power Transformers

The reliability of electrical energy networks depends on the quality and availability of their electrical equipment, e.g., power transformers. Local failures inside their insulation can lead to breakdowns resulting in high outage and penalty costs. To prevent these destructive events, power transformers are tested for partial discharge (PD) activity in a routine test before shipment. Furthermore, PD activity can be evaluated as a diagnostic measurement on-site (on-line or off-line) or be constantly monitored during service using the ultra-high frequency (UHF) method. In this thesis, a calibration procedure is proposed for the UHF method used in power transformers, which is lacking so far. The calibration process is required to ensure both reproducibility and comparability of UHF measurements. Only a calibrated UHF measurement procedure can be deemed reliable and eventually be introduced to supplement in (site-)acceptance tests of power transformers. The proposed calibration method considers two factors: The influence of the UHF sensors' sensitivity and that of the UHF instrument characteristics, including accessories like cables, pre-amplifier, etc. The UHF instruments' influence is corrected by using a defined and invariable test signal as a reference for all recording devices comparable to the calibration method used in IEC 60270 for electrical PD measurement. The sensitivity of the UHF sensor is addressed by a characterization of UHF sensors using the antenna factor (AF) measured in a special reproducible setup, i.e., a GTEM cell. In this thesis, a self-built GTEM cell is presented, which is oil-filled to address the environmental conditions inside a transformer where the sensor will be used. With such a cell, influences on the AF of UHF sensors are investigated, and it is shown that sensor sensitivities measured in an air-filled cell can be corrected to the oil environment. A practical evaluation of the proposed calibration procedure is performed in a laboratory setup on a distribution transformer with different UHF instruments and sensors using artificial PD signals and real high voltage driven PD sources. Finally, this thesis identifies future research topics, which may be needed to improve the proposed UHF calibration procedure for power transformers and the UHF method in general.

The new edition of this book incorporates the recent remarkable changes in electric power generation, transmission and distribution. The consequences of the latest development to High Voltage (HV) test and measuring techniques result in new chapters on Partial Discharge measurements, Measurements of Dielectric Properties, and some new thoughts on the Shannon Theorem and Impuls current measurements. This standard reference of the international high-voltage community combines high voltage engineering with HV testing techniques and HV measuring methods. Based on long-term experience gained by the authors the book reflects the state of the art as well as the future trends in testing and diagnostics of HV equipment. It ensures a reliable generation, transmission and distribution of electrical energy. The book is intended not only for experts but also for students in electrical engineering and high-voltage engineering.

Maintaining appropriate power systems and equipment expertise is necessary for a utility to support the reliability, availability, and quality of service goals demanded by energy consumers now and into the future. However, transformer talent is at a premium today, and all aspects of the power industry are suffering a diminishing of the supply of knowledgeable and experienced engineers. Now in print for over 80 years since initial publication in 1925 by Johnson & Phillips Ltd, the J & P Transformer Book continues to withstand the test of time as a key body of reference material for students, teachers, and all whose careers are involved in the engineering processes associated with power delivery, and particularly with transformer design, manufacture, testing, procurement, application, operation, maintenance, condition assessment and life extension. Current experience and knowledge have been brought into this thirteenth edition with discussions on moisture equilibrium in the insulation system, vegetable based natural ester insulating fluids, industry concerns with corrosive sulphur in oil, geomagnetic induced current (GIC) impacts, transportation issues, new emphasis on measurement of load related noise, and enhanced treatment of dielectric testing (including Frequency Response Analysis), Dissolved Gas analysis (DGA) techniques and tools, vacuum LTCs, shunt and series reactors, and HVDC converter transformers. These changes in the thirteenth edition together with updates of IEC reference Standards documentation and inclusion for the first time of IEEE reference Standards, provide recognition that the transformer industry and market is truly global in scale. -- From the foreword by Donald J. Fallon Martin Heathcote is a consultant specializing in power transformers, primarily working for utilities. In this context he has established working relationships with transformer manufacturers on several continents. His background with Ferranti and the UK’s Central Electricity Generating Board (CEGB) included transformer design and the management and maintenance of transformer-based systems. * The definitive reference for all involved in designing, installing, monitoring and maintaining high-voltage systems using power transformers (electricity generation and distribution sector; large-scale industrial applications) * The classic reference work on power transformers and their applications: first published in 1925, now brought fully up to date in this thirteenth edition * A truly practical engineering approach to design, monitoring and maintenance of power transformers – in electricity generation, substations, and industrial applications.

“Evaluating Measurement Accuracy, 2nd Edition” is intended for those who are concerned with measurements in any field of science or technology. It reflects the latest developments in metrology and offers new results, but is designed to be accessible to readers at different levels: scientists who advance the field of metrology, engineers and experimental scientists who use measurements as tool in their professions, students and graduate students in natural sciences and engineering, and, in parts describing practical recommendations, technicians performing mass measurements in industry, quality control, and trade. This book presents material from the practical perspective and offers solutions and recommendations for problems that arise in conducting real-life measurements. This new edition adds a method for estimating accuracy of indirect measurements with independent arguments, whose development Dr. Rabinovich was able to complete very recently. This method, which is called the Method of Enumeration, produces estimates that are no longer approximate, similar to the way the method of reduction described in the first edition removed approximation in estimating uncertainty of indirect measurements with dependent arguments. The method of enumeration completes addressing the range of problems whose solutions signify the emergence of the new theory of accuracy of measurements. A new method is added for building a composition of histograms, and this method forms a theoretical basis for the method of enumeration.Additionally, as a companion to this book, a concise practical guide that assembles simple step-by-step procedures for typical tasks the practitioners are likely to encounter in measurement accuracy estimation is available at SpringerLink.

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Engineering Metrology and Measurements is a textbook designed for students of mechanical, production and allied disciplines to facilitate learning of various shop-floor measurement techniques and also understand the basics of mechanical measurements.