Analysis of transient action influence in power transformer

This article is focused on the theory of unacceptable effect on transformer winding, mainly the overvoltages and the mechanical forces. In the next part of the article is described the measurement of selfdischarging voltage frequency dependence on transformer. The second measurement shows one of the possible type of SFRA method. The measurement results lead us only to the conclusion that some changes of the winding condition have occurred

Fault diagnostics of transformer winding in time and frequency domain

The paper presents basic overview of measuring methods and fault diagnostics on the power transformers and illustrating measurement on transformer winding using with methods of impact test and frequency response analysis (SFRA). Impact test and SFRA method are often used for analyzing of the insulation between coil threads or themselves of windings and for detection of the attenuated winding sections of transformers. There methods enable detecting early condition of the winding faults. In the paper is presented experimental measurement on distribution three-phase transformer 22/0.4 kV without operation by time and frequency domain by impact test and SFRA method. It was used comparison of measured curve for all phases using with mathematical statistical methods. It was found fault coil into primary winding of coil phase A

MEASUREMENT AND DIAGNOSTICS OF POWER TRANSFORMER BY FREQUENCY METHODS

Paper presents experimental diagnostics of insulating system oil-paper for power transformers, mainly by progressive frequency method – dielectric spectroscopy. The introduction of the article is described the base analyzing for measurement insulating elements (oil and paper) of power transformers. The next part of article is described application of dielectric frequency domain spectroscopy (FDS) method for high-voltage power transformers. Diagnostic methods are used for measurement of insulating state of high-voltage devices with insulating parts as oil-paper. It was present that the values of these measuring results are highly impacted by the temperature of operating during the experimental diagnostics. Conductivity and moisture between dielectric transformer paper and insulating oil in a dielectric system are highly dependent from internal and ambient temperature. In the final section the article are presented experimental values of the diagnostic analysis for an operating oil traction transformer at different internal temperatures and conditions (with oil filling and without)

THERMOVISION DIAGNOSTICS OF ELECTRICAL MACHINES

This article analyzes the problems of prophylactic diagnostics and analysis of electrical machines using thermovision diagnostics. It examines the basic principles and uses of non-contact temperature measurement. The knowledge of the problems diagnostic of electrical machines in service without disassembly enables us to use more efficient thermo-diagnostic methods and to localize the failures that determine the quality of electrical wiring and equipment

Analyse of SF6 Properties in High-Voltage Equipments and its Optimal Utilization with Combination N2

The fundamental characteristics and properties of SF6 and its mixtures with N2 and CO2 are given. Current wave-forms of initial stages of negative corona discharge formation in a short negative point-to-plane gap have been measured with nanosecond time resolution in the mixtures N2 + SF6, at the pressures 50 kPa and for various contents of SF6 and overvoltages. Current pulses in this mixture with low concentration of SF6 are described using the streamer-based theory.<br /

Methods of Humidityanalysis in Transformer Oil

To prevent failure states of transformer, we performed different types of measurements. We made measurements of a frequency dependence of capacity of test transformer immersed in tank with transformer oil. The capacity illustrates a momentary state of the measured equipment and its variations to indicate the changes in the transformer oil. Water content in the transformer oil causes deterioration of its insulation and, finally, thermal defect of solid insulation

High-freqeuncy analysis of three-winding autotransformers 400/121/34 kV

This article deals with a description of methods of an experimental analysis concerning the actual condition of windings and magnetic circuit of the autotransformer, which is required in power transmission companies all over the world

The verification methodics of the effects of short-circuit currents in windings of the power transformers

The windings of power transformers must be designed so, that the effect of short-circuits currents, which can emerge in an operation, will not start up on them the destruction or the deformation of the mechanical or thermal character. Except for permanently deformation results of the effects of short-circuit current come to also by correct ditnensioning of electric equipment to progressive ageing. Which can make worse his mechanical properties. The article deals Ivith the diagnostic method. Which enables to anticipate such state.<br /

Experimentálna analýza výkonových transformátorov metodou SFRA

Medzi súčastné a najefektívnejšie metódy analýzy vinutia transformátorov je možné pokladať metódu SFRA. Vďaka tejto metóde môžeme detekovať účinky skratových prúdov, nadprúdov a iných javov poškodzujúcich vinutie a magnetický obvod transformátora bez jeho rozobratia a následného zisťovania porúch na vinutí, čo je časovo náročné

Development of Electrical Breakdown in Transformer Oil

Power transformers are key equipment for transfer and distribution of the electric power. Considering the significance of the power transformers in the electric system, their price and possible damages occurred by accidents, it is necessary to pay attention to their higher prevention. To prevent failure states of transformers, we perform different types of<br />measurements. They shall illustrate a momentary state of the measured equipment and if necessary to draw attention in advance to changes of parameters, which have specific relationship to no-failure operation of the equipment. The conditions under which breakdown of composite liquid/ solid insulation can occur, e.g. in transformer, play an important role in designing such insulation. The liquid, mainly mineral oil, generally constitutes the weakest part of insulation and a great amount of work has been devoted to the study of streamers, which appear in the gaseous phase, and most often are triggering the failure of insulation