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Badania off-line izolatora przepustowego transformatora WN

Bernatt Jakub, Gawron Stanisław, Glinka Tadeusz, Polak Artur

Maszyny Elektryczne : zeszyty problemowe

2022

Nr 1 (127)

29--34

W artykule przedstawiono schemat zastępczy izolatora i program badań off-line napięciem stałym, to jest: 1) załączenie napięcia stałego o wartości Up i pomiar prądu ustalonego I60; 2) odłączenie napięcia Up i zwarcie układu izolacyjnego na czas tz; 3) rozwarcie układu izolacyjnego i pomiar przebiegu napięcia uod (t) do wartości maksymalnej Uod max. Parametrami diagnostycznymi są: napięcie - Up, rezystancja - R60, czas zwarcia - tz, napięcie - Uod max i stała czasowa τod. Parametry te, wyznaczone dla izolatora nowego i zapisane w jego metryczce, stanowią fingerprint.

The article presents an insulator substitute diagram and an off-line DC voltage test program, that is: 1) switching on DC voltage with the value of Up and measurement of the steady current I60; 2) disconnection of the voltage Up and short-circuit of the insulation system for the time tz; 3) opening of the insulation system and measurement of the voltage waveform uod (t) to the maximum value of Uod max. The diagnostic parameters are: voltage - Up, resistance - R60, short-circuit time - tz, voltage - Uod max and time constant τod. These parameters, determined for the new insulator and recorded in his record are a fingerprint.

Effect of burnishing on the corrosion properties of Ni-5%Al AND Ni-5%Al-15%Al2O3 coatings obtained by plasma spraying

Starosta R.

Journal of KONES

2014

Vol. 21, No. 1

273--280

The Ni-5%Al alloy coatings and Ni-5% Al-15%Al2O3 composite coatings were obtained by plasma spraying method. The PN120 gun was used. The coatings onto a shaft made of austenitic stainless steel (X5CrNi 18-10) were sprayed. The coatings were subjected to turning, burnishing. The evaluation of corrosion properties were based on the measurements of corrosion current density and corrosion potential (polarization method), the charge transfer resistance and exponent of constant phase element impedance (electrochemical impedance spectroscopy method). Corrosion tests were performed in replacement seawater (3.5% sodium chloride solution). On the basis of studies, the effect of finishing type on the corrosion properties of plasma sprayed coatings has been demonstrated. The lowest corrosion current density was found for Ni-5% Al coatings after burnishing, icorr value equal to 0.96 A/cm2, and the charge transfer resistance was 27007 Ωcm2. The lowest resistance to corrosion of turned Ni-5%Al-15%Al2O3 composite coatings was observed. These coatings were characterized by the following parameters of corrosion process: icorr = 17.64 A/cm2, Rct = 2137 Ωcm2. Burnishing caused increased corrosion resistance of coatings. Due to reduced roughness and waviness are obtained reduction of the area of the actual burnished coatings compared to turned coatings. Thus, it is resulting in reduced values of corrosion current density. After finishing treatment, the plasma sprayed Ni-5%Al-15%Al2O3 coatings characterized by lower corrosion resistance compared to the alloy coating. The presence of the reinforcing phase in the coating promotes the increase of the porosity. The plasma sprayed coatings on nickel matrix had a tendency to localized corrosion in sodium chloride solution.