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1

Measurement of sprinkled and encapsulated space charge in homo-multilayer dielectric samples using PEA method

Florkowski Marek, Kuniewski Maciej

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2022

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Vol. 70, nr 2

art. no. e140686

EN

High voltage DC insulation plays an important role, especially in power transmission systems (HVDC) but also increasingly on medium voltage levels (MVDC). The space charge behavior under DC voltage has great importance on electrical insulation reliability. This paper reports investigations of encapsulated space charge in homo-multilayer dielectric materials using the pulsed electro-acoustic (PEA) method. The charge has been introduced on the homo-layer interface by corona sprinkling prior to encapsulation. Two doses of charge density were accumulated on the dielectric surface in two types of dielectric materials Kapton and LDPE. The polarization DC voltage was applied in 2 min intervals in steps corresponding to an effective electric field strength in a range of 8–40 kV/mm for Kapton and 10–50 kV/mm for LDPE. The PEA-based detected space charge was compared at the initial, reference stage, prior to charge accumulation, and after corona sprinkling of defined charge density. The evaluation was based on the PEA time-dependent charge distributions and charge profiles referring to the DC polarization field strength. The goal of the experiment was to identify the relationship and the character of the known sprinkled and encapsulated charge inside homo-layered materials using the PEA method. According to the observations, the ratio between sprinkled charge densities is proportional to the encapsulated, charge densities measured by the PEA method on the interfacial homo-layer for the Kapton specimen. In the case of LDPE, a fast decrease of interfacial charge was observed, especially at a higher polarization field above 10 kV/mm. The encapsulation of the known charge amount can be extended to different types of multilayer material. The presented methodology might be used also for extended calibration of the PEA measurement system.

2

The effect of protrusions on the initiation of partial discharges in XLPE high voltage cables

AlShaikh Saleh Mohammad, Refaat Shady S., Olesz Marek, Abu-Rub Haitham, Guziński Jarosław

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 1

art. no. e136037

EN

This paper is focusing on 3D Finite Elements Analysis (FEA) based modelling of protrusions as defects or imperfections in the XLPE high voltage cable. This study is aiming to examine the impact protrusions have on the initiation of partial discharges. Spherical and ellipsoidal protrusions with different sizes at the conductor screen of the high voltage cable is an essential content of this paper. In addition, a spherical gas-filled void is placed inside and outside the protrusions, and a water tree produced from protrusions is under consideration. The partial discharge influence taking place at the protrusions and the stress enhancement factor is determined for all the variations mentioned to quantify the rise in the inception of partial discharges due to the protrusions.

3

Ludwik Badian fizyk materiałów dielektrycznych

Chrzan K. L.

Maszyny Elektryczne : zeszyty problemowe

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2018

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Nr 4 (120)

137--141

PL

W artykule opisano biografię i prace naukowe Ludwika Badiana. Z perspektywy lat zdumiewa zaskakująco szybka kariera Ludwika Badiana. Młody, wówczas bezpartyjny absolwent Politechniki został dyrektorem Państwowego Instytutu Telekomunikacyjnego już w drugim roku pracy, zaledwie ze stopniem mgr inż. Imponuje również wypromowanie 29 doktorów w okresie 18 lat (1967-1984).

EN

This paper describes biography and scientific works of Ludwik Badian. From the years perspective surprisingly quick carrier of Ludwik Badian is amazing. The young, not belonging to the PZPR party alumni of Wroclaw University o Technology with the title engineer was appointed to the director of State Telecomunication Institute after one year work in this Institution. He conferred 29 doctor degrees in the period of 18 years (1967-1984).

4

Modelling of new generation plasma optical devices

Litovko I. V., Goncharov A. A., Dobrovolskiy A. N., Naiko L. V., Naiko I. V.

Nukleonika

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2016

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Vol. 61, No. 2

207--212

EN

The paper presents new generation plasma optical devices based on the electrostatic plasma lens configuration that opens a novel attractive possibility for effective high-tech practical applications. Original approaches to use of plasma accelerators with closed electron drift and open walls for the creation of a cost- -effective low-maintenance plasma lens with positive space charge and possible application for low-cost, low-energy rocket engine are described. The preliminary experimental, theoretical and simulation results are presented. It is noted that the presented plasma devices are attractive for many different applications in the state-of-the-art vacuum-plasma processing.

5

Elektryzacja rozproszonych kropel aerozoli cieczy przewodzących

Lewandowski M.

Przegląd Elektrotechniczny

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2014

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R. 90, nr 10

144-147

PL

W pracy przedstawiono proces elektryzacji kropel aerozoli wytworzonych przez głowicę z naddźwiękowym przepływem gazu. W celu uniknięcia tzw. „efektu ekranowania” występującego podczas elektryzacji indukcyjnej, zaproponowano elektryzację rozproszonych kropel aerozoli. Uzyskane wyniki wskazują silną zależność parametru Q/m od wydatku wody oraz na złożoność procesu elektryzacji rozproszonych kropel aerozoli.

EN

The process of electrification of aerosol particles dispersed by a pneumatic sprayer with supersonic air flow is presented in this paper. To avoid the shielding effect in induction charging of aerosol, the droplets electrification process following the dispersion of liquid was proposed. Results have shown, that the Q/m factor values power type dependence of the liquid feed rate and the droplets electrification following the dispersion was a complex process.

6

Computation of electric field corresponding to space charge in water-treed power cable insulation

Stancu C., Notingher P. V., Notingher P., Plopeanu M.

Przegląd Elektrotechniczny

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2010

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Nr 5

114-118

EN

The paper presents the calculation of the electric field due to space charge associated to water trees in polyethylene-insulated power cables. For numerical computations the measured thermal step currents with currents computed with a Comsol Multiphysics software for various values of the space charge density and water trees lengths are compared. For electric field computation different average water concentrations in treed areas were considered and the influence of ionic space charge on insulation ageing is presented.

PL

Przedstawiono obliczenia pola elektrycznego wywołanego przez przestrzenny rozkład ładunków w izolacji polietylenowej kabli z zawilgoceniem. Porównano pomierzone zmiany prądu z obliczonymi za pomocą programu Comsol Multiphysics dla rożnych wartości gęstości ładunków. Obliczenia pól elektrycznych wykonano dla rożnych zapleceń kabla i rożnego rozkładu ładunków oraz wtrąceń wody w szczelinach izolacji. Uwzględniono wpływ jonizacji przestrzeni na izolacje.

7

Comparative studies of dc and ac measurement methods used in dielectric spectroscopy

Zubel Z.

Przegląd Elektrotechniczny

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2007

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R. 83, nr 10

6-9

EN

In this paper dispersive curves were measured by dc and ac methods. An attempt has been undertaken to verify the hypothesis that a dielectric containing space charge, examined by actual value method, gives different measurement results from the ones, examined by time response method. If the measurement results obtained by the both methods for the same sample do not differ from each other, it means that in the examined object no space charge exists.

PL

W niniejszej pracy zmierzono charakterystyki dyspersyjne metodami stało- i zmiennoprądowymi. Podjęto próbę zweryfikowania hipotezy, że dielektryk zawierający ładunek przestrzenny, badany metodą wartości chwilowych, daje inne wyniki pomiarowe niż badany metodą czasowej odpowiedzi. Jeżeli natomiast wyniki pomiarowe uzyskane obiema metodami na tych samych próbkach pokrywają się, oznacza to, że w badanym obiekcie nie występuje ładunek przestrzenny.

8

Space charge characteristics in polymer dielectric films

Fujita S., Kamei Y.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

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2004

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Vol. 40, nr 15

242-247

EN

These the space charge density in polyimide films (thickness of 125 µm) was measured using the pulsed-electroacoustic (PEA) method at room temperature in air. The specimen is set between the upper and lower electrodes. Pulse voltage is applied between the electrodes to vibrate the space charge in the specimen and generate an elastic wave. Using a piezoelectric element adhered to the lower electrode, the elastic wave is converted into an electrical signal. The signal is measured with a digital oscilloscope via an amplifier and analyzed by a computer to obtain the space charge density and distribution. The negative d.c. voltage was applied to the specimen from the upper electrode. The negative space charges appeared on the upper side of the specimen and the positive space charges appeared of the lower side of the specimen increased as the voltage was increased. Moreover, the space charge density of PEEK(Poly-Ether-Ether-Ketone) was measured and we are studying the differences in these both characteristics at present.

9

Partial discharge analyses ‒ a comparison of different parameters used

Benzerouk D., Patsch R., Menzel J.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

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2004

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Vol. 40, nr 15

46-50

EN

In the past many approaches have been made to use partial discharge signals to monitor and characterize degradation processes in electric equipment. For the on-line monitoring of large machines or transformers or periodic off-line inspections in many cases only the change of the phase angle distributions of the occurrence of discharges is taken as an indicator for ageing processes in the insulating system. This is sufficient as an indication for the need of a more detailed examination, but often even with off-line experiments the actual change in the defect and especially its relevance for the service life remains unclear. A more detailed insight into the physics of the local degradation processes and their relevance for the ageing process of the equipment can be gained in most cases only with measurements with a continuously increased voltage load and the evaluation of the data via Pulse Sequence Analysis. The paper will discuss and compare different methods to analyze partial discharge data, starting with 'simple' frequency distributions of different parameters of the externally applied voltage load derived from the data set as a whole. As the main point sequence correlated data such as time differences between consecutive discharges will be discussed. It will be shown that in dependence on the type of defect the significance of different parameters is different.

10

Measurements of frozen-in polarization in PET electrets using E-j method

Motyl E.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

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2004

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Vol. 40, nr 15

41-45

EN

Step elcctroacoustic (SEA) and thermally stimulated depolarisation (TSD) techniques were applied for analysis of electret slate in polyethylene-terephthalate samples after corona charging at low and high temperatures. Measurements of electric field distributions E and current density jTSD during thermally stimulated discharging allow to get information on real charge density and quasi-frozen polarisation in dielectric. The above E-j method is a useful tool for measurement of local values of real and polarization charges in PET electrets and their decay in time. Positive and negative coronas as well as temperature of charging affect the storage of real charges and polarisation in PET electrets.

11

A current flow problem for amorphous solids. A case of weak and mean electric fields

Świstacz Bronisław

Archives of Electrical Engineering

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2004

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Vol. 53, nr 2

121--130

EN

A space charge transport problem for a planar capacitor system is presented. For a solid placed between two electrodes it is assumed that the carrier generation and recombination processes are independent of an external electric field. Some singular cases of the current flow trough the system are considered. It is found that the system can act as an almost perfect blocking diode (or a voltage stabiliser), and also, it is found that the negative differential resistance is a singularity of space charge transport through the system.

PL

Rozważa się transport ładunku elektrycznego w układzie płaskiego kondensatora, zakładając że procesy generacyjno-rekombinacyjne nie zależą od zewnętrznego pola elektrycznego. Stwierdza się, że układ zachowuje się jak prawie idealna dioda blokująca (stabilizator napięcia), a ujemna rezystancja jest osobliwością transportu ładunku przestrzennego.

12

Space charge dominated beam transport in the K130 cyclotron injection line

Heikkinen P.

Nukleonika

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2003

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Vol. 48,suppl.2

21-24

EN

High intensity H- beams are injected into the K130 cyclotron [1] for isotope production and for proton induced fission studies. Earlier, when protons were accelerated as positive ions, the beam intensity was limited by beam losses in the extraction system from the cyclotron. Stripping extraction of negative ions removed this limitation. However, now space charge effects in the injection beam line limit the beam intensity. At present, the maximum practical H- beam intensity at the inflector is about 0.25 mA, which gives 40-50 žA of extracted proton beam. Calculations predict that the injection beam line from the ion source to the matching quadrupoles below the cyclotron can transfer about 1 mA of 6 keV H- beam, which also was measured. The quadrupole section has a smaller transmission. Also a significant portion of the beam is lost during the last 2 m in the axial hole. General rules for maximum beam intensity as a function of beam line parameters such as beam tube aperture, distance of focusing elements, beam charge, mass and energy are given for different kinds of focusing systems (solenoids, FODO and FOFDOD quadrupole structures). As a conclusion, some suggestions to improve the transmission of the injection line are given.

13

Computer simulation of the space charge dominated beam dynamics for external injection into the JINR Phasotron

Onischenko L., Samsonov E.

Nukleonika

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2003

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Vol. 48,suppl.2

29-34

EN

A project of increasing the beam intensity of the 660 MeV JINR proton Phasotron up to 50 žA by an external injection of the H- beam with energy of 5 MeV is now under design. Computer simulation of the space charge dominated beam dynamics in Phasotron is reported. As follows from the simulation, the capture efficiency does not change too much when the beam space charge is taken into account.

14

A space-charge problem including trapped positive charge. A case of solar cell

Świstacz B.

Archives of Electrical Engineering

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2002

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Vol. 51, nr 3

243-267

EN

A theoretical description of an interior of a solid for space charge is continued. Carrier generation and recombination conditions are considered. On this basis it is found that the metal-solid-metal system can act as a perfect blocking diode. A solar cell problem is discussed.

PL

Problem formowania się ładunku przestrzennego w ciele stałym jest kontynuowany. Rozważa się warunki generacji i rekombinacji nośników. Na tej podstawie stwierdza się, że układ metal-ciało niemetaliczne-metal może działać jak idealna dioda blokująca. Rozwija się problematykę baterii słonecznej.

15

Local space charge effect in conventional avalanche counters at moderate specific ionization

Sernicki J.

Nukleonika

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2000

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Vol. 45, nr 2

125-131

EN

The purpose of this investigation is the determination of a simple criterion of local space charge effect in conventional avalanche counters at moderate specific ionization. Parallel-plate avalanche counters (PPAC) with an electrode spacing d from 0.1 to 0.4 cm have been used to register low-energy alpha particles at n-heptane vapour pressures of p ? 5 Torr. The criterion determined is a simple h/pm function describing the variability of the product of effective gas amplification and actual particle energy loss, where both the numerical h coefficient and the exponent m assume different values for the various values of d. The product variability at higher gas pressures in PPAC detector – having regard to practical side of criterion determined – can be relatively well described by a single linear function. The results obtained are discussed from their veracity point of view.

16

Numerical model of electrostatic barrier effect in a point-plane air gap in presence of positive space charge

Boubakeur A., Mokhnache L., Boukhtache S.

Archives of Electrical Engineering

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1999

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Vol. 48, nr 3

323-340

EN

A model allowing determination of the electric field and potential in the presence of a space charge (positive ions) determined on the basis of the knowledge of efficient ionisation factor alpha(-) has been developed. The distribution of the space charge is done in spherical concentric volumes. The calculation is developed in a hyperboloidal point-barrier-plane arrangement under a positive voltage. The polarisation field is taken into account. To calculate the electric field the finite element method has been applied. Results show that electric stress in the air gap decreases due to the space charge left in the point-barrier gap, but it increases suddenly at the handle of the avalanches and on the barrier surface facing the point. This latter effect related to the presence of the dielectric barrier is due to the polarisation charge. The space charge variation is not smooth. It presents a sudden increase when alpha(-) changes.

PL

Przedstawiono model umożliwiający obliczenia rozkładu potencjału i pola elektrycznego w obecności dodatniego ładunku przestrzennego, wyznaczonego w oparciu o znajomość efektywnego współczynnika jonizacji alfa(-). Ładunek przestrzenny występuje w wyodrębnionej przestrzeni kulistej. Analiza dokonywana jest w układzie elektrod ostrze hiperboloidalne - bariera - płyta z dodatnią biegunowością ostrza. W analizie uwzględniono pole polaryzacyjne bariery. W obliczeniach polowych wykorzystano metodę elementów skończonych. Uzyskano potwierdzenie, że ładunek przestrzenny powoduje zmniejszenie natężenia pola, które wzrasta gwałtownie w przypadku procesów lawinowych, gdy powierzchnia ładunku przestrzennego dociera do ostrza. Taki efekt bariery dielektrycznej związany jest z polaryzacją ładunku. Wartość ładunku przestrzennego zmienia się gwałtownie ze zmianą współczynnika alfa(-).