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The lightning impulse generators are expensive equipments that are used to check the basic insulating level of the elements that operate in the electrical power systems. The impulse generator of the Center of Researches and Electric-energetical Tests was manufactured in the ancient East Germany, and when the Socialistic Field disappeared, left it without support neither option of repairing, because of this, at the age of ten years of exploitation, it began to have recurrent damages in the circuits that commanded its functioning. This took it to the technical drop. The objective of this work is giving back the functionality of this equipment. Its stability of operation was proved, obtaining the established wave shape for the lightning impulses tests. The voltage divider relation and relation between the outer pick voltage and the r.m.s. charge voltage were obtained also. [ABSTRACT FROM AUTHOR]

The study of the electrical phenomena that originate during the operation of the transformers is of vital importance to predict the consequences that these will bring and to improve the design of the system and of the transformer itself. To carry out these studies it is necessary to use existing simulation tools. The accuracy of the response of the simulation process depends on the degree of detail and the veracity of the data, as well as the type of mathematical model used, so it is necessary to obtain these data and their application in the most suitable model for the simulation of each phenomenon. This paper presents the results of a project that consisted in obtaining, through simulation, the impulse voltage distribution within the transformer windings from a detailed model with the final objective of verifying the effectiveness of the insulating systems used in the transformers prototypes used. [ABSTRACT FROM AUTHOR]

The diagnosis of transformers has been a subject to which much attention has been paid due to the importance it has in order to increase their life time and the quality of their exploitation. There are publications on techniques whose objectives are to predict the state of these machines. One of the tests used to diagnose mechanical defects in this equipment is the "Sweep Frequency Response Analysis" (SFRA). This article presents the SFRA tests carried out on two three-winding transformers in subtransmission substations. An analysis of each case is made based on the answers and results obtained, confirming that in the descriptions of the SFRA response patterns that make the standards for failure modes, there is ambiguity and it is difficult to discriminate between a mode of fails, another or perceive if more than one is present. [ABSTRACT FROM AUTHOR]