Wyniki wyszukiwania - BazTech

1

Measurements on treeing resistance with a new electrode design.

Huuva R., Englund V., Gubański S., Hjertberg T.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

|

2007

|

Vol. 46, nr 19

75-81

EN

Electrical treeing in high voltage cable insulation has been studied for several years and today the mostly used laboratory test set-up is the needle-plane electrode configuration. In this paper another electrode configuration is suggested. The new electrode configuration makes use of a thin tungsten wire as the electrode that delivers the high and divergent electric stress needed to initiates electrical tree growth in insulation material. Multiple electrical trees are formed during the testing, which allows determining the treeing initiation field as well as the rate of tree growth. A comparison between tree initiation conditions in samples prepared of pure LDPE and XLPE materials is shown and the data are fit by 3-parameter Weibull distributions. Electrical trees start to develop in LDPE material at lower field strength than in XLPE one and two different mechanisms of tree initiation are identified in LDPE. Improvement imposed on the treeing initiation field by adding voltage stabilizing additives to XLPE is also illustrated.

2

Influence of thermal aging process on dielectric response of oil-paper insulation.

Gielniak J., Graczkowski A., Gubański S., Moranda H., Mościcka-Grzesiak H., Walczak K.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

|

2007

|

Vol. 46, nr 19

113-117

EN

This paper presents results of dielectric response measurements in frequency domain obtained at different temperature for oil impregnated paper samples containing different amount of moisture. Brief description of the sample preparation and thermal aging are also included. Dielectric responses of unaged and thermally aged paper samples were investigated at different temperature and the obtained results were used for defining respective master curves and activation energies. Discrepancies of the results from similar samples are also presented. Finally, statistical spread of the data from similar samples was presented with error bars and discussed about their influence on distinguishing the dielectric response of paper samples having different moisture intakes.

3

Sustainable development within electric power engineering

Gubański S.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

|

2006

|

Vol. 43, nr 17

100-104

4

Analiza częstotliwościowa parametrów dielektrycznych jako narzędzie diagnostyczne materiałów na przykładzie układu izolacyjnego papier-olej.

Graczkowski A., Walczak K., Gielniak J., Ekanayake Ch., Gubański S., Mościcka-Grzesiak H.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

|

2006

|

Vol. 44, nr 18

37-40

PL

W artykule przedstawiono możliwości wykorzystania spektroskopii dielektrycznej w badaniach właściwości materiałów. Zaprezentowano wyniki badań odpowiedzi dielektrycznej izolacji papierowo-o I ej owej w aspekcie oceny jej zawilgocenia i zestarzenia. Porównano parametry dielektryczne próbek preszpanu i papieru impregnowanego o różnym stopniu zawilgocenia i zestarzenia w różnych temperaturach.

EN

The paper presents applications of dielectric spectroscopy in investigations of materials properties. The results of dielectric spectroscopy investigations of oil-paper insulation was presented in aspect of moisture content and aging evaluation. Dielectric parameters of impregnated paper and pressboard of different moisture content and aging state was compared at various temperatures.

5

Experiences from on-site dielectric spectroscopy measurements on power transformers

Blennow J., Ekanayake C., Bartnicki A., Gubański S.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

|

2004

|

Vol. 40, nr 15

62-69

EN

Dielectric spectroscopy field measurements were conducted both in frequency domain (FDS) and in time domain (PDC) on ten power transformers, most of them rated 130 kV/40 MVA. In addition, oil samples were taken for moisture content analyses and for conductivity measurements. The transformers selected for the measurements were of different types, originating from different manufacturers and having different age, up to 50 years old. Some of them have been known as being in bad condition. In general, the majority of the transformers were low loaded prior to the measurements. On two of the units the measurements were performed both before and after oil regeneration. Results of the oil analyses are compared with estimates obtained from the well-known XY-model and the simplified X-model. The results of the modelling show that both FDS and PDC provide information about the state of insulation. Oil temperatures as well as thermal equilibrium are critical factors for obtaining reliable results. The spectroscopy measurements provide better estimates of moisture content at low sample temperatures than the traditional Karl Fisher analyses.