STRUCTURAL-MECHANICS ANALYSIS OF THE 10G TRANSFORMER IMPACT

Transportation of the power transformers from the site of production to the site of the exploitation is very complex and sensible task. During transportation, the transformer can be subjected to a variety of different impacts registered either during railway transportation or during on/off loading. The transformer should be designed to sustain the high accelerations appearing often during transportation. Transformer are usually equipped with the impact recorder to registry the acceleration behavior during the transport. In the current paper, we give an overview on the structural-mechanics analysis of 10g impact on the power transformer registered during the railway transportation of the transformer from Canada to US

DETERMINATION OF RESONANCE FREQUENCIES AND VIBRATION CHARACTERISTICS OF STATORS HAVING ENCASED CONSTRUCTION

An accurate assessment of the resonance frequencies of stators is essential for designing a quiet electrical machine. Also, detailed information about the vibration characteristics of the stator is of much interest. In the newer construction of stators, the stator-core is encased tightly in the frame. This construction is considered to be simpler and more economical as it eliminates the use of ribs between the core and the frame. An analysis, of a general nature, for the determination of the various resonance frequencies and mode shapes of stators having encased construction is presented in the thesis. As the general frequency equation is derived on a three-dimensonal basis, it delivers information about not only the radial vibrations of the stator but also about torsional and axial vibrations. In addition, the flexural vibrations along the machine-length are taken into account in the analysis. The validity of the analysis is confirmed by experimental results which were obtained from the literature for stators of small as well as of large machines. A detailed study of the vibration characteristics of a representative stator is carried out and the results are presented in a generalized form. The advantages of the encased construction of stators over the conventional construction from the vibration considerations are discussed. Finally, the. validity of the simplified frequency equations which are derived from the general frequency equation, is checked

Power transformer characteristics and their effect on protective relays”, 33rd Western Protective Relay Conference

Abstract There are a variety of protective relays using different measuring techniques to provide reliable and secure transformer protection. This includes electro-mechanical, solid state and numerical relays. Within each group, various algorithms exist. Advancements made to transformer technology and design over the past 3 decades, have changed the characteristics of the transformer inrush current, and have often introduced incorrect operations in the existing harmonic restraint relays during energization. Topics to be presented include: • Comparison between old and newly developed more accurate calculations of peak values, magnitude of the second harmonic, and other parameters of Inrush current • Design and system parameters which influence the magnitude and wave-shape of inrush current, e.g. winding design and connections, core material, core joint geometry, short-circuit capacity of network, etc. • Impact of transformer design & performance parameters and new developments in the Transformer technology on magnitudes and nature of inrush current • Current transformer influence on the speed, selectivity, and dependability of transformer protection This paper will address these topics as well as provide solutions for selecting and setting transformer protection. It is to be noted that the parts of the paper provided by the ABB Power Transformers (Dr. Girgis and Mr. teNyenhuis) are sections 1 -3

Power transformer characteristics and their effect on protective relays”, 33rd Western Protective Relay Conference

Abstract There are a variety of protective relays using different measuring techniques to provide reliable and secure transformer protection. This includes electro-mechanical, solid state and numerical relays. Within each group, various algorithms exist. Advancements made to transformer technology and design over the past 3 decades, have changed the characteristics of the transformer inrush current, and have often introduced incorrect operations in the existing harmonic restraint relays during energization. Topics to be presented include: • Comparison between old and newly developed more accurate calculations of peak values, magnitude of the second harmonic, and other parameters of Inrush current • Design and system parameters which influence the magnitude and wave-shape of inrush current, e.g. winding design and connections, core material, core joint geometry, short-circuit capacity of network, etc. • Impact of transformer design & performance parameters and new developments in the Transformer technology on magnitudes and nature of inrush current • Current transformer influence on the speed, selectivity, and dependability of transformer protection This paper will address these topics as well as provide solutions for selecting and setting transformer protection. It is to be noted that the parts of the paper provided by the ABB Power Transformers (Dr. Girgis and Mr. teNyenhuis) are sections 1 -3