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1

FTIR and FDS assessment of mineral oil under low electrical discharge

Boudraa Saliha, Benabed Fadila, Fofana Issouf, Mokhnache Leila

Diagnostyka

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2022

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Vol. 23, No. 2

art. no. 2022208

EN

Transformers are crucial elements in the transmission and distribution of electrical energy. The importance of diagnosing these equipments are two-fold: (1) the necessity of service reliability and (2) the likelihood to avoid economic and environmental concerns. Under service conditions, the electrical and thermal stresses or chemical contaminants may degrade the insulation oil inside the transformer and cause incipient failures or reduce its service life. Partial discharges well recognized to be among the most common stresses that can lead to slow but steady degradation of insulating oil in transformers. The present work aims at understanding the influence of low energy electrical discharge on mineral oil based on two spectroscopic methods: FTIR spectroscopy and Frequency Domain Spectroscopy (FDS). An electrical fault has been created by continuous discharge of 10 kV on the surface of various oil samples according to the ASTM D6180. From the FDS results, it was found that the amount of charge carriers and moisture increased with the aging time elapsed that influences the conduction phenomena and in turn, increases the dissipation factor. These results are confirmed by the FTIR results, which show that the intensity of the peak absorbance of the C–H and C-C functional group decreased with aging. The application of these two methods may help monitoring the condition of oil. A combined FTIR and FDS measurements highlighted the correlations between modifications in electrical properties and changes in the chemical structure of the oil under electrical accelerated ageing.

2

Charakterystyki dyspersyjne zespolonej przenikalności elektrycznej papierów aramidowych NOMEX® T410 oraz T910 impregnowanych różnymi cieczami dielektrycznymi

Wolny Stefan

Przegląd Elektrotechniczny

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2020

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R. 96, nr 8

147--150

PL

W artykule przedstawiono wyniki badań eksperymentalnych zespolonej przenikalności elektrycznej w dziedzinie wysokiej częstotliwości, przeprowadzone na próbkach izolacji impregnowanej. Warstwę izolacji stałej wykonano z dwóch rodzajów papierów elektrotechnicznych: w pełni aramidowego typu NOMEX® T410 oraz z celulozowo-aramidowego typu NOMEX® T910. Jako impregnat wykorzystano trzy rodzaje cieczy dielektrycznej: olej mineralny Nynas Nytro 10X, ester syntetyczny Midel 7131 oraz ester naturalny Midel en1204. Celem badań była obserwacja oraz analiza zmian właściwości dielektrycznych tych materiałów. W badaniach uwzględniono wpływ oddziaływania temperatury w zakresie od 20°C do 100°C, co odpowiada typowym warunkom eksploatacji izolacji impregnowanej w transformatorach mocy.

EN

The article presents the results of experimental research on complex electric permittivity in the high frequency domain, carried out on impregnated insulation samples. The solid insulation layer was made of two types of electrotechnical papers: NOMEX® T410 fully aramid type and NOMEX® T910 cellulose-aramid type. As impregnation, three types of dielectric liquid were used: mineral oil Nynas Nytro 10X, synthetic ester Midel 7131 and natural ester Midel en1204. The purpose of the research was to observe and analyze changes in the dielectric properties of these materials. The studies took into account the impact of temperature in the range from 20°C to 100°C, which corresponds to the typical conditions of exploitation of impregnated insulation in power transformers.

3

Halloysite intercalated by potassium acetate

Mariusz Adamczyk, Katarzyna Małycha, Karol Kułacz, Michał Pocheć, Kazimierz Orzechowski

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 6

235--243

EN

Halloysite was intercalated by the mechanochemical technique from dry components. The process efficiency of 50% was achieved. The obtained intercalate differed from the material acquired using an aqueous solution of potassium acetate. The material was analyzed employing electron microscopy, thermogravimetry, X-ray powder diffraction, and dielectric spectroscopy. It was found that the molecules and/or ions present in the interlayer spaces retain some possibility of movement. This property of the material is promising for potential application as low expensive absorbers of electromagnetic radiation.

4

Eksperymentalne badania elektroreologicznych właściwości olejów smarnych zawierających ciecz jonową. Cz. 2, Badania w spektroskopii dielektrycznej

Juda Jarosław, Kałdoński Tomasz Jan, Kałdoński Tadeusz, Mrukiewicz Mateusz

Biuletyn Wojskowej Akademii Technicznej

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2020

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Vol. 69, nr 2

43--69

PL

W artykule przedstawiono wyniki badań w tzw. spektroskopii dielektrycznej dwóch mieszanin oraz ich składników, tj. bazowych olejów izolujących i cieczy jonowych jako dodatków aktywnych elektrycznie. W pierwszej części badań [1] stwierdzono występowanie efektu ER w obu mieszaninach, gdy poddane były oddziaływaniu zewnętrznego stałego pola elektrycznego o natężeniu E ≤ 0,2 kV ⋅ mm⁻¹. Efekt elektroreologiczny był jednak krótkotrwały i niepowtarzalny na tej samej próbce cieczy, co sugerowało istotne zmiany jej struktury wewnętrznej. Stosując analizator impedancji HP 4192A, oceniono zmienność ich stałych dielektrycznych (ε) oraz rezystancji (R) i konduktywności (σ) w funkcji częstotliwości (f) stałego pola elektrycznego BIAS-u (DC), dla różnych wartości przyłożonego napięcia (U). Wykonano również testy powtarzane na tych samych próbkach mieszanin w celu zaobserwowania, jak pierwotnie przyłożone pole BIAS-u wpływa na dalsze zachowanie cieczy w polu elektrycznym. Na podstawie rezultatów badań uzyskano podstawę potwierdzenia symptomów zmian struktury wewnętrznej mieszanin, będących wynikiem działania zewnętrznego pola elektrycznego, prowadzących do zaniku efektu ER. W celu rozpoznania mechanizmu zaniku efektu ER zostaną przeprowadzone badania mikroskopowe in situ wytworzonych mieszanin poddanych działaniu zewnętrznego pola elektrycznego.

EN

The paper presents the results of investigations of two mixtures and their ingredients i.e. base insulating oils and ionic liquids as electrically active additives using, so called, dielectric spectroscopy. In part 1 of the study [1], the ER effect was found in both mixtures when they were subjected to an external constant electric field with the intensity of E ≤ 0.2 kV ⋅ mm⁻¹. However, the electrorheological effect was short-lived and unique on the same liquid sample, which suggested significant changes in its internal structure. Using the HP 4192 A Hewlett Packard impedance analyzer, the variability of their dielectric constans (ε), as well as the resistance (R) and the conductivity (σ), as a function of the frequency (f) of the constant electric field BIAS-u (DC) was assessed for different values of the applied voltage (U). Repeated tests were also carried out on the same samples of mixtures to observe how the originally applied BIAS field affects the further behavior of the liquid in the electric field. Based on the results of the research, the basis for confirming the symptoms of changes in the internal structure of mixtures, resulting, from the action of an external electric field, leading to the disappearance of the ER effect was obtained. In order to recognize the mechanism of disappearance of the ER effect, in situ microscopic tests of the prepared mixtures, subjected to an external electric field, will be carried out.

5

The molecular dynamics of nematic liquid crystal confined in porous membranes treated by different surfactants

Różański Stanisław Andrzej

Opto-Electronics Review

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2019

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Vol. 27, No. 4

339--344

EN

The molecular dynamics of the well-known nematic liquid crystal 4-n-pentyl-4′-cyanobiphenyl geometrically restricted in Anopore and Synpor porous membranes with various pore structure and treated by different surfactants (namely decanoic acid and lecithin) is compared. In the Anopore membrane the chosen surfactants induce the homeotropic orientation of the molecules on the walls of the cylindrical pores and observed corresponding relaxation processes (librational modes) are practically the same. The dielectric measurements of lecithin treated Synpor membranes reveals the reorientation of the molecules from planar to homeotropic on the complex multilayer structure present in their volume. The dielectric strengths of the observed two molecular processes (δ-process and librational mode) are inversed in the ratio compared to the untreated membranes. The observed differences in molecular dynamics results from the orientation of the liquid crystal molecules in untreated and treated membranes and the structure of the membranes themselves.

6

Structural analysis and dielectric relaxation mechanism of conducting polymer/volcanic basalt rock composites

Bulgurcuoğlu Ayşe Evrim, Karabul Yaşar, Kiliç Mehmet, Özdemir Zeynep Güven, Erdönmez Seda, Misirlioğlu Banu Süngü, Okutan Mustafa, İçelli Orhan

Materials Science Poland

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2019

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Vol. 37, No. 3

353--363

EN

In this work, polypyrrole and polythiophene conducting polymers (CPs) have been synthesized and doped with volcanic basalt rock (VBR) in order to improve their dielectric properties for technological applications. The structure and morphology of the composites with different VBR doping concentrations were characterized by FT-IR and SEM analyses. The best charge storage ability was achieved for maximum VBR doping concentration (50.0 wt.%) for both CPs. Dielectric relaxation types of the composites were determined as non-Debye type due to non-zero absorption coefficient and observation of semicircles whose centers were below Z′ axis at the Nyquist plots. It was also ascertained that VBR doping makes the molecular orientation easier than for non-doped samples and reduced energy requirement of molecular orientation. In addition, AC conductivity was totally masked by DC conductivity for all samples at low frequency.

7

Analiza charakterystyk dyspersyjnych papieru aramidowego impregnowanego estrem naturalnym i syntetycznym w dziedzinie wysokich częstotliwości

Wolny S.

Przegląd Elektrotechniczny

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2018

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R. 94, nr 10

168--171

PL

W artykule przedstawiono wyniki badań laboratoryjnych wykonanych na próbkach izolacji aramidowej impregnowanej estrami, naturalnym i syntetycznym. Próbki papieru aramidowego poddano procesowi przyspieszonej degradacji termicznej, który polegał na jego wygrzewaniu jeszcze przed impregnacją w temperaturze 250°C przez określony czas. Analizie poddano wpływ stopnia zestarzenia papieru aramidowego na charakterystyki dyspersyjne pojemności i współczynnika strat w zakresie temperatury od 20°C do 100°C.

EN

The paper presents the results of laboratory investigations carried out on aramid insulation impregnated with esters, natural and synthetic. Aramid paper samples were subjected to the process of accelerated thermal degradation, which consisted in its heating still before impregnation in temperature of 250°C for a definite time period. The analysis was subjected to influence of the aramid paper aging degree on dispersion characteristics of capacitance and loss factor in the temperature range from 20°C to 100°C.

8

Parameters of LC molecules’ movement measured by dielectric spectroscopy in wide temperature range

Chausov D. N., Kurilov A. D., Belyaev V. V., Kumar S.

Opto-Electronics Review

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2018

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Vol. 26, No. 1

44--49

EN

Dielectric properties of a nematic liquid crystal (NLC) mixture ZhK-1282 were investigated in the frequency range of 10²–10⁶Hz and a temperature range of -20 to 80°C. On the basis of the Debye’s relaxation polarization model dielectric spectra of temperature dependence of the orientational relaxation time τ and the dielectric strength δe were numerically approximated at the parallel orientation of a molecular director relative to alternating electric field. Influence of ester components in the mixture plays crucial role in relaxation processes at low temperature and external field frequency. The activation energy of the relaxation process of a rotation of molecules around their short axis was measured in a temperature interval of -20 to +15°C in which the dispersion of a longitudinal component of the dielectric constant takes place. The energy of potential barrier for polar molecules rotation in the mesophase was calculated. The value of the transition entropy from the nematic to isotropic phase was obtained from this calculation. The values of the coefficient of molecular friction and rotational diffusion were obtained by different methods. The experimental data obtained are in a satisfactory agreement with the existing theoretical models.

9

Examination of the Properties of Samples from Glass-Epoxy Core Rods for Composite Insulators Subjected to DC High Voltage

Wieczorek K., Jaroszewski M., Ranachowski P., Ranachowski Z.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1281--1286

EN

This article presents the results of an examination performed on a set of samples of glass-epoxy core rods used in composite insulators with silicone rubber housings. The goal of the examination was to test the aging resistance of the core material when exposed to Direct Current (DC) high voltage. Long term exposure of a glass-epoxy core rod to DC high voltage may lead to the gradual degradation of its mechanical properties due to the ion migrations. Electrolysis of the core material (glass fiber) may cause electrical breakdown of the insulators and consequently lead to a major failure. After being aged for 6000 hours under DC high voltage, the samples were subjected to microscopic analysis. Their chemical composition was also examined using Raman spectroscopy and their dielectric losses and conductance in the broad range of frequencies were tested using dielectric spectroscopy.

10

Odpowiedź dielektryczna w dziedzinie częstotliwości układu izolacyjnego celuloza-mieszanina estru syntetycznego i oleju mineralnego

Fatyga P., Morańda H.

Przegląd Elektrotechniczny

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2016

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R. 92, nr 10

38--41

PL

W artykule przedstawiono zagadnienia związane z oceną dynamiki wymiany oleju mineralnego na ester syntetyczny w izolacji celulozowej oraz problem oceny zawilgocenia izolacji celulozowej napełnionej mieszaniną oleju mineralnego z estrem syntetycznym. Z badań wynika, że proces wymiany oleju mineralnego na ester syntetyczny jest długotrwały, a ocena zawilgocenia metodą FDS na podstawie wzorców celuloza-olej mineralny skutkuje błędem niedoszacowania.

EN

The article presents issues related to the assessment of the dynamics of exchange of mineral oil to synthetic ester in cellulose insulation, and the problem of moisture evaluating of cellulose insulation filled with a mixture of mineral oil with synthetic ester. The research shows that the process of replacing mineral oil to synthetic ester is long, and the evaluation of moisture using FDS method based on patterns of cellulose-mineral oil results in an underestimation.

11

Analysis of the Phase Transitions in BNT-BT Lead-Free Ceramics Around Morphotropic Phase Boundary by Mechanical and Dielectric Spectroscopies

Silva Jr P. S., Diaz J. C. C. A., Florêncio O., Venet M., M’Peko J. C.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 1

17--20

EN

In this work, the syntheses and characterization by mechanical and dielectric spectroscopies of (1-x) Bi0.5Na0.5TiO3-xBaTiO3 (BNT-100xBT), with x = 0.05, 0.06 and 0.07, lead-free piezoelectric ceramics is reported. Ceramic samples of BNT-BT have been prepared by mixed-oxide method and then conventionally sintered. X-ray diffraction patterns of sintered samples, indicated for BNT-7BT the presence of tetragonal (P4mm) complex perovskite structure, whereas for BNT-5BT and BNT-6BT the samples exhibit a mixture of tetragonal (P4mm) and rhombohedral (R3c) crystalline phases, which reveal the presence of a morphotropic phase boundary (MPB) in the BNT-BT system. Measurements of internal friction, Q-1, and the storage modulus, E’, as a function of temperature at various frequencies were carried out in a Dynamic Mechanical Analyzer (DMA), in the temperature range from 0ºC to 600ºC. Dielectric profiles are recorded in the frequency range from 1kHz to 100kHz and the temperature range from room temperature to 475ºC. Mechanical loss spectra obtained for investigated compositions of BNT-BT samples showed different frequency-independent anomalies. Two main anomalies for BNT-5BT and BNT-6BT, observed around 100ºC and 430ºC were associated with the ferroelectric-antiferroelectric and antiferroelectricparaelectric phase transitions, respectively. The results obtained from mechanical loss measurements were supported by dielectric relaxation spectra. For BNT-7BT, outside the MPB, four different frequency-independent processes were observed.

12

Dielectric properties and molecular motions of liquid crystal molecules in 4-(2-methylbytyl) phenyl 4-(4-octylphenyl) benzoate liquid crystal having blue phase (CE8)

Otowski W., Lewińska G.

Materials Science Poland

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2015

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Vol. 33, No. 2

418--429

EN

Blue phase liquid crystals exhibit unique properties which are used in the new type of display. A blue-phase liquid crystal display was first presented commercially by Samsung in 2007. The blue-phase-three-color pixel display eliminates the need for color filters. This type of display uses blue-phase multi-component liquid crystal. Considering the one-component systems, it turns out that they are stable only in a very narrow range of temperatures between the isotropic and the chiral nematic phase (about 1 K). In 2005, a wide temperature range BP multi-component system was reported by researchers from the University of Cambridge. There are still several unsolved problems left. One of them is chemical stability and reliability. Therefore, the knowledge of molecular dynamics of blue phase liquid crystal is a prerequisite for understanding of blue-phase multi-component system. Understanding the molecular dynamics of a single component liquid-crystalline blue phase system can facilitate the solution of these problems. We present the molecular dynamics investigation of 4-(2-methylbytyl)phenyl 4-(4-octylphenyl) benzoate (CE8), which may be a good candidate to form materials suitable for blue-phase liquid crystal displays.

13

Badanie olejów napędowych metodą dielektrometrii opartą na spektroskopii impedancyjnej

Macioszek Ł.

Pomiary Automatyka Kontrola

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2014

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R. 60, nr 11

942--944

PL

W pracy podjęto próbę oceny przydatności dielektrometrii w badaniu właściwości olejów napędowych typu premium. Przy użyciu systemu pomiarowego do spektroskopii impedancyjnej wykonano wstępne badania, na podstawie których wyznaczono względną przenikalność elektryczną badanych próbek. Wyniki badań pozwalają stwierdzić, że przy uwzględnieniu pewnych ograniczeń, dielektrometria oparta o spektroskopię impedancyjną może pozwolić na analizę olejów napędowych.

EN

In the paper an attempt was made to evaluate the diesel fuels using dielectric spectroscopy to verify experimentally that it can be used to characterize these fuels. Five samples of winter premium diesels from different vendors were examined. Impedance of diesel fuels was measured in the frequency range of 0.01 Hz – 5 kHz with the use of EG&G/Princeton Applied Research laboratory system for impedance spectroscopy. Measurement results are presented in the form of Bode plot in Fig. 1. Complex resistivity of the samples was calculated on the basis of measured impedance and is presented on fig. 2. The simplest electrical equivalent circuit of the measuring cell (parallel R-C circuit) was used to calculate the capacitance and thus dielectric constant of diesel fuels (expression 5) from the collected measurements of impedance. Dielectric constant of diesel fuels’ samples is presented in Fig. 3. In the Fig. 1 and 2 one can notice a diversity in the obtained results that depend on the supplier and hence the exact chemical composition of the tested diesel. This diversity is not so noticeable in Fig. 3 what may be very important in cases when dielectric spectroscopy is used to detect some substances that can be harmful for the engine. The tests’ findings show that dielectric spectroscopy can be used to determine some of the properties of diesel fuels. Ability to detect additional substances in diesel would however depend on the difference in values of dielectric constant of the matters.

14

Dielectric spectroscopy of liquid crystals : electrodes resistivity and connecting wires inductance influence on dielectric measurements

Perkowski P.

Opto-Electronics Review

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2012

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Vol. 20, No. 1

79-86

EN

Dielectric spectroscopy is a very useful experimental method for liquid crystal investigation. Electrodes made from indium tin oxide (ITO) or gold are widely used in measuring cells. During the dielectric spectroscopy measurements performed for smectic liquid crystalline mixture it was found that detection of some important relaxation modes in paraelectric SmA*, ferroelectric SmC* and antiferroelectric SmCA* phases for frequencies higher than 0.2–0.5 MHz is not possible. The measuring setup does not allow us to measure such relaxations due to its own dielectric response covering the dielectric response of liquid crystalline medium. One can observe the spurious contribution for high frequency part of the dielectric spectrum, due to non-zero resistivity of electrode material or non-zero inductivity of connecting wires. In this paper, the new model was introduced. Its final equations show how to calculate parameters of relaxations observed in liquid crystals, from dielectric response of the empty and filled measuring cell. The experimental proof of strong influence of measuring setup properties on effective (measured) values of dielectric permittivities was shown.

15

Techniki spektroskopii dielektrycznej w badaniu jakości materiałów i produktów rolniczych

Skierucha W., Wilczek A.

LAB Laboratoria, Aparatura, Badania

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2012

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R. 17, nr 1

6-14

PL

Spektroskopia dielektryczna opisuje właściwości dielektryczne próbki materiału w funkcji częstotliwości. Takimi materiałami mogą być obiekty agrofizyczne, np. gleba, owoce, warzywa, półprodukty i produkty przemysłu spożywczego, ziarno itp. Techniki spektroskopii dielektrycznej umożliwiają pomiar nieniszczący oraz nieinwazyjny obiektów agrofizycznych dając szybką ocenę ich wilgotności oraz jakości.

16

Numerical elimination methods of ITO cell contribution to dielectric spectra of ferroelectric liquid crystals

Perkowski P.

Opto-Electronics Review

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2011

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Vol. 19, No. 2

176-182

EN

Indium tin oxide (ITO) electrodes are widely used for liquid crystal applications as well as for measuring cells. Unfortunately, ITO layer possesses its own non zero resistivity R which produces (with the capacity C) the cut-off frequency f0 of RC circuit. Dielectric spectroscopy cannot be performed for high frequencies because of high frequency losses caused by the cell behaviour. Four procedures for estimating and extracting high frequency losses in ITO cells are presented and compared in this paper. Their limitations and viability are discussed.

17

How to determine parameters of soft mode from dielectric spectroscopy performed using cells with ITO electrodes?

Perkowski P.

Opto-Electronics Review

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2011

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Vol. 19, No. 1

76-82

EN

Indium tin oxide (ITO) electrodes are widely used for liquid crystal applications as well as for measuring cells. Unfortunately, ITO layer possesses its own non zero resistivity R, which produces (with the cell capacity C₀) the cut-off frequency f₀ of RC₀ circuit. From this reason, dielectric spectroscopy for high frequencies cannot be performed directly. The limits of classical method of extracting high frequency losses are shortly discussed. The new method of extracting high frequency losses is used for the first time for the experimental data. The new method can also evaluate the shrinkage of measuring cell gap after filling with liquid crystal.

18

Influence of geometrical parameters and temperature of oil-paper insulation on analysis results by means dielectric response method

Gielniak J.

Przegląd Elektrotechniczny

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2010

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R. 86, nr 11b

220-222

EN

The paper presents result of analysis of dielectric response in frequency domain for several power transformers. The main goal of this analysis is determination of moisture content in solid insulation. It is result from the authors experiences that same basics information required to correct analysis are unavailable or uncertain in many cases. Authors carried out analysis of dielectric response for power transformers taking into consideration the fact that the geometry and temperature can differ from initially assumed.

PL

W artykule przedstawiono wyniki analiz odpowiedzi dielektrycznej izolacji kilkunastu transformatorów energetycznych, w wyniku których otrzymuje się informacje na temat zawilgocenia izolacji stałej. Jednakże często dane wejściowe niezbędne do przeprowadzenia analizy odpowiedzi dielektrycznej są trudnodostępne lub obarczone dużym błędem. Przeprowadzono zatem analizę odpowiedzi dielektrycznej przy założeniu, że kluczowe parametry (temperatura i geometria izolacji) nie są dokładnie znane. Oceniono wpływ tych czynników na uzyskiwane wyniki analiz.

19

Analiza możliwości zastosowania metody FDS do badania zawilgocenia transformatorów o izolacji lakier-papier-olej

Gielniak J.

Przegląd Elektrotechniczny

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2010

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R. 86, nr 11b

217-219

PL

Artykuł przedstawia analizę możliwości zastosowania techniki FDS (Frequency Domain Spectroscopy) do oceny zawilgocenia izolacji stałej transformatorów energetycznych, których uzwojenie dolnego napięcia wykonane jest w technologii przewodów transponowanych izolowanych lakierami żywicznymi. Badaniom poddano transformator energetyczny o izolacji lakier-papier-olej oraz dwa rodzaje lakieru. Stwierdzono, że cienka warstwa lakieru zastosowana w analizowanym transformatorze nie wpływa znacząco na odpowiedź dielektryczną.

EN

The paper presents an analysis of possibility of the FDS technique application for moisture evaluation in power transformers with varnished transposed wires. The power transformer and two types of insulating varnish were investigated. The author concluded that thin layer of varnish doesn't have the significant influence on the dielectric response of transformer insulation.

20

Dielectric spectroscopy of liquid crystals : theoretical model of ITO electrodes influence on dielectric measurements

Perkowski P.

Opto-Electronics Review

|

2009

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Vol. 17, No. 2

180-186

EN

Indium tin oxide (ITO) layers are widely used to make electrodes in measuring cells, because these layers are transparent and electrooptical investigations can be performed using such prepared cells. It was found during the dielectric spectroscopy measurements, performed for smectic liquid crystalline mixture, that it is not possible to detect some important relaxation modes in paraelectric SmA*, ferroelectric SmC*, and antiferroelectric SmCA* phases for the frequencies higher than 300 kHz. The measuring cell does not allow to measure relaxations, because its own dielectric behaviour covers the dielectric response of a liquid crystalline medium. One can observe the spurious contribution for high frequency part of the dielectric spectrum, due to the finite resistance of ITO layers. The theoretical model was introduced, which shows how to calculate relaxations related to liquid crystals from dielectric response of the empty and filled measuring cell. The proof of strong influence of cell properties on effective (measuring) values of dielectric permittivities was shown.