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Assessment of methods of marking LED sources with the power of equivalent light bulb

Tabaka P., Rozga P.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2017

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Vol. 65, nr 6

883--890

EN

This article presents considerations on the assessment of marking LED sources with the power of an equivalent light bulb. This problem was studied both on the basis of calculations and measurements performed. 17 LEDs of different powers and luminous fluxes were tested. Calculations assessing conformity with the declared power showed that an important disadvantage for most of the LED sources results from the method of marking them with the power of an equivalent light bulb from the point of view of the luminous flux emitted. Manufacturers do not do this correctly, misleading the potential user. Meanwhile, measurements performed in different ambient temperatures indicated that for only 4 from among the 13 LED sources studied the given value of the power of an equivalent light bulb may be recognized as in accordance with the actual state of affairs and still with a reservation that specified ambient temperature shall be required. In other cases the values of power quoted are either understated or overstated.

2

Streamer propagation in a non-uniform electric field under lightning impulse in short gaps insulated with natural ester and mineral oil

Rozga P.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2016

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Vol. 64, nr 1

171--179

EN

This article describes the comparative experimental studies on streamer propagation in natural ester and mineral oil under a high voltage lightning impulse. These studies were concentrated around the small electrode gaps and the point-plane electrode arrangement. The spatial shapes of the developing streamers, light emission and propagation velocity were analyzed and compared between the two different dielectric liquids. In both of them two streamer propagation modes were registered during the studies performed. Propagation of slow 2nd mode streamers took place below the so-called acceleration voltage while fast 3rd mode streamers developed at acceleration voltage and above. Comparing the streamer shapes corresponding to a given voltage polarity, no visible differences were observed between the liquids tested. Concerning the light emission, higher frequencies of light pulses were registered however in the case of natural ester. The significant differences between both liquids were noticed in the value of the acceleration voltage estimated. In the case of positive polarity streamers started to develop in natural ester as a 3rd mode at lower value of testing voltage than in the case of mineral oil. For negative polarity, within the applied testing voltages, 3rd mode streamers appeared only in natural ester. On this basis, the fundamental conclusion is that natural ester may have a lower ability of preventing the development of fast and energetic 3rd mode streamers, even at small electrode gaps.

3

The measurement of partial discharges in voltage transformers using DDX 7000 instrument

Rozga P.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 9b

294-295

EN

The experiences of the author, gained during the measurements of partial discharges using DDX 7000 instrument, are presented in this article. The experiences concern the measurements carried out on the real electrical objects such the inductive voltage transformers. The measurement systems and procedures, and the methods of the visualization of the results obtained using DDX 7000 are also presented.

PL

W artykule przedstawione zostały doświadczenia autora związane z pomiarami wyładowań niezupełnych z użyciem detektora DDX 7000. Doświadczenia te dotyczą pomiarów wykonanych na rzeczywistych obiektach, którymi były indukcyjne przekładniki napięciowe. Zaprezentowano układy i procedury pomiarowe oraz metody wizualizacji wyników pomiarów uzyskanych z wykorzystaniem urządzenia DDX 7000.