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La2Ti2O7 ceramic has a perovskite-like structure with super-high Cuire temperature (Tc ~ 1460 ℃), which is an excellent candidate for the application as a high-temperature accelerator sensor used at beyond 1000 ℃. The high temperature electrical conductivity resulting from charge carrier transport has a major influence on the sensitivity of sensors. Here, Zn was introduced as an acceptor into La2Ti2O7 ceramics for high-temperature electrical properties. All the samples show pure perovskite-like structure with P21 space group and compact microstructure. With the introduction of Zn up to x = 0.08, the insulation resistance of the ceramics was enhanced more than 1000 times. Impedance spectroscopy and modulus spectroscopy were used to investigate the high-temperature transport of charged carrier. Interestingly, the acceptor doping resulted in an increasing concentration of oxygen vacancies, but a significant increase in both electrical insulation and activation energy of the ceramics was observed. The thermal activation mechanism is responsible for the high-temperature charge carrier transport. It is suggested that although the concentration of oxygen vacancies increase, Zn doping depresses the motion of oxygen vacancies in perovskite-like structure. The results provide a method to improve the insultation of high-temperature piezoelectric ceramics. [ABSTRACT FROM AUTHOR]

It is known that cable channels, often consisting of multilayer polymer pipes, are used to protect cable lines. Taking into account the fact that cables are heated during operation, important criteria for the reliability of the cable channel are increased heat resistance and flame resistance - for the inner layer of the pipe. Even the most reliable system cannot completely eliminate the possibility of cable damage up to a short circuit in the line. In case of cable breakage, bare wires will be located on the wall of the polymer pipe. In this case, finding the place of cable breakage through the wall of a pipe traditionally made of HDPE dielectric is extremely difficult. When choosing a cable channel of a special design made of special electrically conductive PCM, even in case of damage to the conductive line, it will be possible not only to avoid further destruction, but also to determine the breakdown location. In the assortment of POLYPLASTIC Group there are fundamentally new technical, technological and constructive solutions of current-seeking pipes for cable channels produced under the trademark ELECTROPIPE OS RS OMP, which allows you to determine the place of cable breakdown with an accuracy of up to 12 m. The paper presents a comparative study of multilayer polymer pipes of the ELECTROPIPE RS series, ELECTROPIPE OS RS with an internal refractory layer and ELECTROPIPE OS RS OMP with an internal electrically conductive layer based on a special refractory composition and carbon nanotube concentrate (CNTC). The content of CNTC is 5–10 wt %. All tests were carried out on real pipe samples. The physicomechanical (tensile strength, modulus of elasticity and elongation) and electrophysical characteristics (insulation resistance), as well as resistance to flame (exposure to hot wire, a test for flammability according to the ROSSETI method) were investigated. [ABSTRACT FROM AUTHOR]

Copyright of Techno.com is the property of Universitas Dian Nuswantoro, Fakultas Ilmu Komputer and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The medium-voltage components in the ignition installations for gasoline engines contain electroinsulating materials that lose their properties over time. The purpose of this paper is to measure and analyze the insulation resistance, dielectric absorption ratio and polarization index of the insulation of materials (three types of materials) used for medium-voltage distributors, for several operating periods, in automotive ignition installations. Experiments were conducted with old (operation tens of thousands of km, some with surfaces that have been cleaned) and new medium-voltage distributors, and a megohmmeter was used to measure, over time, the insulation resistance between the central terminal and the output terminals at different test voltages. The insulation resistance of the distributors depends on the use: in the old ones, they have values of tens of GΩ (e.g., up to 100 GΩ) and, in the new ones, of the order of TΩ (e.g., 4–7 TΩ). The more distributors are used, for the same distributor, there are greater differences between the measurements made between terminals and the average values (87% for used distributors, respectively, 2% for new ones). For new or less used distributors, higher values were obtained for the dielectric absorption ratio (1.26–1.27; for used ones, 0.91–0.95) and polarization index (1.15–1.25; for used ones, 0.96–1.15). The results show the importance of the volume insulation resistance of the electroinsulating material compared to the surface resistance and the insignificant improvement when cleaning the internal and external surfaces of the medium-voltage distributors. [ABSTRACT FROM AUTHOR]

The monitoring of electrical insulation resistance is one of the most important parameters characterizing the reliability of the on-board electric-power system and the safety of its operation. A significant part of the faults and failures inherent in elements of the shipboard power system is associated with reducing insulation electric resistance with respect to the ship hull caused by exposure to high humidity and temperature, as well as mechanical damage to the insulating layer, electrical cables, wires, and electrical devices. The rules of technical operation establish the lowest values of insulation resistance of the elements of the onboard electric-power system with respect to the ship hull. At the same time, the presence of highly branched electrical networks on the ship complicates the problem of centralized and localized insulation resistance monitoring. In addition, the increase in the number of power plants and possible changes in the number of concurrent consumers within the power system, as well as an increase in the contribution of high-voltage electrical onboard equipment, requires a more reliable control system for electrical insulation resistance. The author concludes that, to provide more reliable insulation resistance monitoring of the elements of an onboard power system, it seems relevant to additionally use novel principles and methods for controlling the measurement information in the monitoring system and processing this information, which differ from those traditionally used in the construction of such systems. For this purpose, as well as to improve the characteristics of the insulation resistance monitoring of the electric-power system, it has been proposed to apply the queuing theory with the assessment of its parameters. The onboard presence of a system for the continuous automatic monitoring of insulation resistance is an important component that provides the reliability and safety of ship operation by its crew. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Insulation resistance is a vital factor in dry DC link capacitors (DCLCs), and crucially influences their voltage equalization and energy storage performance. However, at present, there is a lack of experimental observation on the insulation resistance characteristics of DCLCs in the presence of high temperatures and operating voltages. In the present study, the insulation resistance and conductivity of DCLCs are methodically analyzed. For this purpose, the corresponding test platform is appropriately fabricated, the insulation resistance measurement experiments are performed at various temperatures and operating voltages, and the factors affecting the insulation resistance and conductivity of the DCLC are carefully examined. The results reveal that the insulation resistance of the DCLC reduces exponentially with the growth in voltage and operating temperature. When the operating voltage becomes greater than 4480 V or the operating temperature reaches higher than 70 °C, the decline in insulation resistance slows down. The conductivity of metalized polypropylene film in the DCLC increases exponentially with increasing voltage and temperature. By increasing the operating voltage from 1960 V to 5600 V and the temperature from 20 °C to 90 °C, the DCLC's insulation resistance exhibits a descending trend from 891.30 MΩ to 2.14 MΩ, while its conductivity grows from 3.49 × 10−16 S/m to 1.47 × 10−13 S/m. The results reveal that the key factors affecting the insulation resistance of the DCLC are the polypropylene film and the metal evaporated from the metal layer. This research is anticipated to provide a valuable reference for the further development of science and technology pertinent to the insulation resistance of DCLCs. [ABSTRACT FROM AUTHOR]

Insulation resistance (IR) is an essential metric indicating insulation conditions of extruded power cables. To deliver reliable IR simulation as a reference for practical cable inspection, in this paper, four IR degradation models for cross-linked polyethylene-insulated cables under thermal ageing are presented. In addition, the influences of methodologies and temperature profiles on IR simulation are evaluated. Cable cylindrical insulation is first divided into sufficiently small segments whose temperatures are simulated by jointly using a finite volume method and an artificial neural network to model the thermal ageing experiment conditions. The thermal degradation of IR is then simulated by dichotomy models that randomly sample fully degraded segments based on an overall insulation (layer) ageing condition estimation and discretization models that estimate the gradual degradation of individual segments, respectively. Furthermore, uniform and non-uniform temperature profiles are incorporated into dichotomy and discretization models, respectively, for a comparison. The IR simulation results are not only compared between different models, but also discussed around the sensitivity of IR simulation to segment sizes and degradation rates. This provides cable assessment engineers with insights into model behaviour as a reference for their selection of appropriate IR degradation models. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Isolators are one of the assets at PT PLN, which serve as separators between the energized and non-energized parts. Maintenance is performed by replacing damaged isolators when there are indications of reduced insulation resistance. In this journal, the insulation resistance values were measured using a Kyoritsu Insulation Tester and six porcelain isolator samples in various conditions were used. The aim was to determine the extent of the decrease in insulation resistance values, as well as the leakage current and touch voltage values based on Ohm's law formula. Based on the measurement results, the sixth isolator in partially damaged condition is the worst, supported by an insulation resistance value of 800 MΩ for a test voltage of 10kV and 400 MΩ for a test voltage of 5kV. In good condition, the measured insulation resistance value of the isolator is 1 TΩ. Based on the calculation results, in the sixth condition, the leakage current values were 6.25 mA and 25 mA, and the touch voltage values, assuming an average human insulation resistance value of 1000 Ω, were 6.25 Volts and 25 Volts. According to 0520-2.K.DIR.2014 standards, the insulation resistance values meet the requirement that 1kV insulation resistance can be sustained by 1MΩ and are still below the maximum touch voltage limit, which is < 50V effective. [ABSTRACT FROM AUTHOR]

Herein, we present results that emphasize the importance of retaining high insulation resistance in polymer backsheets for the reliable operation of photovoltaic installations. By correlating inverter monitoring data, meteorological data, and spectroscopic information from backsheet materials of photovoltaic modules, we derive performance and degradation rates for inverters connected to photovoltaic modules with several backsheet types. The feasibility of evaluating the degradation status of photovoltaic modules in the field through spectroscopic analysis of the water content in backsheet and encapsulant is demonstrated. We show that an increase in water content is a sign for reduced leakage resistance. Ground impedance was measured alongside relative humidity and temperature for three specific backsheet types. Inverters with polyamide and fluorinated coating/polyethylene terephthalate backsheets showed a significant drop in ground impedance at high humidity, RH > 70%. A loss rate of −2 kΩ/day in ground impedance was found for inverters connected to modules with certain fluorinated backsheets. This value is twice as high as for inverters connected to modules with polyamide backsheets. Time series show that the sensitivity to moisture and water ingress increases with time, especially for modules with polyamide and certain fluorinated backsheets. The worst degradation scenario observed had an annual yield loss of 27% due to inverter outages on humid days. About 25% of inverter trip alerts after 8 years of operation included modules with the specific fluorinated backsheet. In general, the study revealed a distinct backsheet impact on ground impedance and operation of inverters and the resulting yield showing an important role of the choice of polymers for reliable and long‐lasting photovoltaic systems. [ABSTRACT FROM AUTHOR]

The results of studying the effect of thermal-treatment modes and finishing conditions on the rupture strength of woven-glass tapes and fiberglass fabrics and electrical insulation manufactured from them are reported. It is shown that the complete removal of the oiling agent "wax emulsion" from the surface of glass tapes is attained after stepwise thermal treatment at 250–400°C, but the rupture strength decreases by 80% in this case. The finishing of glass tapes with 3-glycidoxypropyltrimethoxysilane after the technical oiling agent is completely removed restores their rupture strength to the level of 35–40% of the initial value (before removing the wax-emulsion oiling agent) and makes it possible to create electrical insulation with water resistance to 1100 h at 23°C and to 7 h at 80°C. [ABSTRACT FROM AUTHOR]

Durability of photovoltaic (PV) modules is of great concern not only from the point of view of cost‐effectiveness but also from the point of view of safety and sustainability. The backsheet of a PV module is one of the most critical parts of the PV module from the point of view of protection and also one of the most important sources of PV modules' failure; hence, it is of great importance to understand its different forms of failure. In this paper we analyze the case of an 8‐MW PV plant, which had suffered a rapid degradation of their PV modules' backsheets. The case is especially relevant as all the PV modules are from the same model and manufacturer but with different backsheet materials (polyamide and fluoropolymer) and different times of exposure: on one hand, all PV modules originally installed in the plant (i.e., 6 years under operation when tested), and also, extra modules that had been stored indoors for replacement and had been mounted in the plant for less than 1 year when tested, serving as reference modules. In this paper we present the signs of degradation of these PV modules after different times of exposure under real operation using different on‐field and laboratory tests. We propose different techniques for rapid diagnosis of backsheet degradation so that the problem can be detected at a very early stage, before it results in major energy losses or in safety issues. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An algorithm for processing insulation resistance measurement data in an electrical network with an isolated neutral is proposed. The features of continuous monitoring of insulation resistance in electrical networks with semiconductor energy converters are considered. A description of a technical solution that meets the requirements of regulatory documents for mining equipment and provides an increase in the speed of the insulation resistance control procedure and protection of electrical equipment is given. The device-operation algorithm is based on the use of a periodic test signal. The test voltage source generates bipolar pulses of a special shape into an AC network. During each period of the test signal, two procedures are performed: charging the capacitance of the electrical network and directly measuring the leakage current in the steady-state mode for the measuring current. Based on the results of leakage current measurements at positive and negative test voltage values, the insulation resistance that is used in the protective disconnection circuit is determined. The decrease in the measurement error is provided by interference compensation during algebraic summation of signals proportional to the leakage current, but is shifted in time by half the period of the test signal. The insulation resistance is calculated by averaging the calculated insulation resistance value over a sliding interval equal to the voltage period of the monitored network. The signal averaged over a sliding interval is continuous; therefore, the measurement result is also formed continuously. The delay in determining when the insulation resistance drops is approximately half the period of the test voltage. Continuous monitoring of insulation resistance in dual-current electrical installations is the basis for safe operation of personnel and equipment. Results of modeling the operation of the insulation resistance control device in an electrical network with thyristor rectifiers are presented. [ABSTRACT FROM AUTHOR]

This article investigates the effects of operating current, soil properties, and UV ageing on the insulation resistance of cables used in the photovoltaic (PV) industry. Based on standardized experimental tests, the temperature-dependent conductivity was measured, and therefore the temperature–conductivity relationship for each cable type is extracted. Using the Arrhenius equation, a mathematical model was developed, which provided the basis for subsequent simulations of the cable insulation resistance based on the thermal properties of the insulation material, surrounding soil, and the current flowing through the conductor. The simulation provided insights into the dynamic changes of the insulation resistance based on the operating parameters. Moreover, the experimental UV ageing of cables used in the PV industry provided important insights regarding the downgrading of the insulation resistance upon prolonged exposure to the sun. [ABSTRACT FROM AUTHOR]

Over operation time, there are a number of internal and external factors that change the characteristics of dielectric materials that are part of the electrical equipment. In areas with high pollution, an important requirement is the acidic chemical compounds in the soil in which the power cables are laid, which penetrate the insulation by infiltration, resulting in changes in the parameters of electrical insulation and causing a decrease in operating time. The paper is focused on the analysis, through a series of experimental determinations, of the effects of stresses to which the power cables laid in acidic environments are subjected, by simulating the operating conditions in the laboratory, obtaining concrete results. It also describes the direct current test installation used in the laboratory and presents the two stages of testing the cable sample inserted in the electrolyte, the first being a stage of accelerating the degradation of the insulation by supplying higher voltages to require insulation, and the second stage being the testing in the absence of the electric field, under the direct action of the chemical compounds from the installation tank. Given that in alternating current, the electric field causes an additional heating of the dielectric due to energy losses by electric polarization, the test is performed in direct current, precisely to be able to monitor the variation of insulation resistance in relation to temperature and losses through conduction currents, as a result of the Joule–Lenz effect and not as a result of the dielectric polarization process. At the same time, the power of the direct current source used is lower compared to that of an alternative current test source and does not contribute to the generation of electrical discharges during testing. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gas discharge tube (GDT) breaks down discharge with surge overvoltage during long-term use. Notably, there is a risk of short-circuit failure due to the drop in insulation resistance after a certain number of discharges, which might be mainly caused by cumulative discharge. This article builds a cumulative discharge experiment platform to analyze the failure mechanism, performed the GDT whole life cycle cumulative discharge experiment and focused on the change law of its insulation resistance and breakdown voltage. For samples that are short-circuited, X-ray observation and vibration testing perpendicular to the GDT axis are conducted to examine the internal micro-morphology without damaging their external structure. The GDT is opened and its internal structure and material properties of the GDT cavity are compared and analyzed by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) methods. The results indicated that the insulation resistance of GDT continuously decreased by several orders of magnitude in the last 10% of the life cycle, and the insulation resistance before failure is generally less than 1 $\text{k}\Omega $. Through X-ray observation of the short-circuit failure sample, two different abnormal growth phenomena in the cavity are found, including flocs between the electrodes and deposits on the tube wall. Further analysis and experiments demonstrated that the flocs between the electrodes and the deposits on the tube wall are the primary factors causing the degradation of GDT insulation performance. The formation mechanism of the two short-circuit modes is explained by the difference in the splash angle and mode of metal particles of different sizes on the electrode surface. [ABSTRACT FROM AUTHOR]

The dielectric properties of insulating liquids are very important for their application as insulation and coolant in electrical devices like transformers. It is important to monitor the health condition of transformers for uninterrupted and economical power supply. For this purpose, the simple insulating materials like pressboard and mineral oils are used. This paper presents an eco-friendly alternative to mineral oil in the form of the synthetic ester oil-based nanofluids. This paper aims to present the effect of nanoparticles on the dielectric dissipation factor and electrical resistivity of ester-based oil. In this paper, we are testing synthetic ester oils for DC resistivity and dielectric dissipation factor (Tan-delta) at different temperatures starting from room temperature up to 80°C by incorporating nanoparticles with 0.02 weight% concentration. Nanoparticles used in this study are Fe2O3, TiO2 and Al2O3. Synthetic ester oil is used as the base oil for testing. These oils are manufactured from raw materials that are basically formed by combining acids and alcohols. The heating chamber is used to heat the oil for different temperatures. Insulation resistance (IR) tester and oil dissipation factor meter are used to determine DC resistivity and dielectric dissipation factor (DDF) of simple synthetic ester oil and nano oil respectively. This paper presents the effect of nanoparticles and temperature on dielectric properties of synthetic ester-based oils. [ABSTRACT FROM AUTHOR]

A measuring instrument is used to measure the insulation resistance of a cable system at a railway control centre. Moreover, online weather data is available as the source of data such as the relative humidity. A data-driven technology can be used for signal detection, signal estimation and signal forecasting. The meaningful characteristics of the data can be extracted by an algorithm so that a relationship is established between the insulation resistance of the cable and the relative humidity. In this way, the remaining lifetime of a cable can be predicted based on the previously observed values. [ABSTRACT FROM AUTHOR]

A measuring instrument is used to measure the insulation resistance of a cable system at a railway control centre. Moreover, online weather data is available as the source of data such as the relative humidity. A data‐driven technology can be used for signal detection, signal estimation and signal forecasting. The meaningful characteristics of the data can be extracted by an algorithm so that a relationship is established between the insulation resistance of the cable and the relative humidity. In this way, the remaining lifetime of a cable can be predicted based on the previously observed values. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a new insulation resistance calculation technique to prevent electric shock and fire accidents due to the dielectric breakdown in the primary insulation section of the IT ground system. The solar power generation market is growing rapidly due to the recent expansion of renewable energy and energy storage systems, but as the insulation is destroyed and fire accidents frequently occur, a device for monitoring the insulation resistance state is indispensable to the IT grounding method. Compared to the conventional algorithm that use a method of multiplying a time constant to a fixed coefficient, the proposed insulation resistance calculation method has a fast response time and high accuracy over a wide insulation resistance range by applying a different coefficient according to the values of the insulation impedance. The proposed dynamic time constant based insulation resistance calculation technique reduces the response time by up to 39.29 seconds and improves the error rate by 20.11%, compared to the conventional method. [ABSTRACT FROM AUTHOR]

Au/Pt thermocouples are considered as an alternative to High Temperature Platinum Resistance Thermometers and are one of the prime candidates to replace them as the interpolating instrument of the International Temperature Scale of 1990 (ITS-90) in the temperature range between about 660 °C and 962 °C. This work presents the results of investigation of two Au/Pt thermocouples that used exclusively quartz glass (SiO2) as insulation material. Measurements in fixed points of Zn, Al, and Ag were realized on these thermocouples as well with interchanged inner insulation made of high purity aluminium oxide (Al2O3). The conducted experiments tested the performance of Au/Pt thermocouples with the use of different insulation materials. The measured electromotive forces were found to be sensitive to the replacement of the quartz glass by aluminium oxide as an insulation material of the Au/Pt thermocouples. This change of insulation has resulted in a temperature increase up to about 0.5 K measured at the freezing point of silver. The decreasing insulation resistance of quartz glass at higher temperatures is believed to be the source of thermoelectric instability. [ABSTRACT FROM AUTHOR]

A bismuth oxide-based multicomponent glass system, xH3BO3-yBi2O3-(1-x-y-δ)MO-dδrare earth oxides (REOs) with MO 5 TiO2, BaO, ZnO, Fe2O3, etc., and lanthanum series-based REOs, for making downhole high-pressure and high-temperature electrical feedthrough package has been developed using hightemperature melt-quenching and sintering technologies. By properly controlling phase structures in material-manufacturing processes, the obtained sealing materials have shown moistureresistant properties in their monoclinic and tetragonal mixed phase structures but strongly hydrophobic properties in their covalent bond tetragonal phase. Sealed electrical feedthrough packages have been evaluated under boiling water immersion and 200°C/30,000 PSI water-fluid-simulated downhole harsh environments. The post electrical insulation measurement has demonstrated to be greater than 1.0 × 1014 Ω electrical resistance. This article will show that such a high-bonding strength and high-insulation strength sealing material could be used to seal electrical feedthroughs and connectors for 300°C/30,000 PSI downhole and subsea wireline, logging while drilling, and measurement while drilling tools' signal, data, and electrical power transmissions. [ABSTRACT FROM AUTHOR]

With the increasing usage of cross‐linked polyethylene (XLPE) power cables, it is more and more important to grasp and manage their insulation status. Nowadays, the distribution cables in urban area are of huge numbers, so it is impossible to carry out the preventive test for every cable. Therefore, it is very helpful to determine cables' testing urgency in a scientific way. Meanwhile, the main cable diagnosis methods in China are insulation resistance and withstanding voltage test, but they are difficult to quantitatively determine cable insulation status. Aiming at solving above challenges, according to the cable fault records in recent years, fuzzy evaluation analysis combining with mutual information is utilised to determine the insulation testing urgency (ITU) based on cable information including service year, laying way, load type, and length. At the same time, frequency domain spectroscopy (FDS) is introduced to diagnose the on‐site cable insulation status quantitatively. Its characteristic parameters, including instantaneous electric susceptibility, DC conductivity, and hopping conductivity, are extracted by improved Havriliak–Negami (H‐N) model and studied to analyse the changing trend before and after cable deterioration. The results show that the lower ITU is, the higher testing urgency is. ITU also has negative correlation with FDS characteristic parameters. [ABSTRACT FROM AUTHOR]

Copyright of Scientific Papers of Electrical & Control Engineering Faculty Technical University of Gdansk / Zeszyty Naukowe Wydzialu Elektrotechniki & Automatyki Politechniki Gdanskiej is the property of Gdansk University of Technology, Faculty of Electrical & Control Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The relevance of the study is conditioned by the need to determine the state and residual life duration of high-voltage cable lines to identify faulty and maintainable cables. The aim of the article is to determine a reliable scientifically grounded criterion for assessment of insulation characteristics of the cables in use and to perform a comparative analysis of the results obtained by the traditional method of diagnosing insulation with the results of a new method of assessment by the return voltage. In this regard, the article deals with the issues related to the testing of cables having oil-impregnated paper insulation, as well as with the issue of switching from planned replacement of cables to assessment of their actual state and period of residual life. The authors propose to use the method of examining the cables by the return voltage using the device for testing electrical insulation "UDEI-1" developed at the department of Electrification and Automation of the Nizhny Novgorod State University of Engineering and Economics. The article presents the results of measuring the return voltage of three cables that operated under different conditions. The cables had different technical state. The analysis of the estimation of the residual life of cables by the return voltage was carried out using such criteria as the PIRV polarization index, the LIRV electrical conductivity index, and the P-factor. The P-factor is the physical criterion demonstrating the aging of paper-oil insulation by the shape of the return voltage curve. It represents such characteristics of insulation aging as moistening. To compare the results of testing the cables by the return voltage with the conventional methods of diagnostics and to determine the actual technical condition of power cables, the authors applied the method of spatiotemporal reflectometry and the method of measuring insulation resistance with the determination of such indicators of state as insulation resistance normalized per one kilometer, absorption coefficient, and polarization index. The results of this article confirm that the return voltage gives a qualitative assessment of the state and degree of aging of cables with impregnated paper insulation. The authors proposed a new system for evaluation of cable condition by weighting coefficients. In this approach, the determination of residual life of cables with impregnated paper insulation is based on the values of the return voltage. Application of the new system gives opportunity to improve reliability of the power lines. Recommendations for the further operation of the studied cables are given. The materials of the article are of practical value for carrying out complex assessment of the technical condition of power cables by the return voltage and can be useful for drawing up a schedule for replacement or repair of cable lines depending on their actual state. [ABSTRACT FROM AUTHOR]

Premature or unplanned removal of power transformers from operation can cause significant losses to energy suppliers and consumers. Therefore, knowing the estimated lifetime and, especially, consumed and remaining lifetimes of transformer insulation is of particular importance. This paper presents the results of a study on the use of transformer winding insulating resistance as a diagnostic factor for the determination of the aM,D and bM,D parameters of the lifetimes lines for the Montsinger and Dakin ageing models. The methods to determine these parameters are presented, both by accelerated laboratory tests and by measuring the windings insulating resistance of the transformers in operation, the method of calculating Dakin line parameters based on the Montsinger parameters (and vice versa) and the calculation of these parameters based on the insulation resistance values and the temperature variation curve of the insulation. Finally, it is shown that the parameters aM,D and bM,D change their values during transformers operation and their numerical calculation is presented for 5 transformers in operation. [ABSTRACT FROM AUTHOR]

Copyright of Technical Electrodynamics / Tekhnichna Elektrodynamika is the property of National Academy of Sciences of Ukraine, Institute of Electrodynamics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present article describes how to use multiparametric diagnostics in maintenance. First, the maintenance is defined and its history is briefly analysed. Subsequently, the maintenance is divided according to current considerations. It is stated that the proactive maintenance represents the state-ofthe- art approach to maintenance management. The use of multiparametric diagnostics, such as vibration analysis, electrodiagnostics, tribodiagnostics, etc., is mentioned. A special attention in the present article is paid to the examples of the use of diagnostics in dynamic and static measurements. The so-called route diagnostics focusing on vibrations, as well as diagnostics of current and voltage values, power input monitoring, spectral analysis of current, and temperature, flow and pressure measurements are mentioned. The measurements of insulation resistance and other parameters of the device drive are also given. The text is supplemented with several pictures showing the results of specific diagnostic measurements from industrial practice. [ABSTRACT FROM AUTHOR]

To ensure electrical safety in electric vehicles equipped with a high-voltage battery pack, an insulation monitoring circuit is indispensible to continuously monitor the insulation resistance during charging or driving. Existing methods such as to inject specific signals into the monitoring circuit and earth help to extract the resistance value from the voltage waveform. However, parasitic or stray capacitances in the monitoring circuit, which might introduce higher-order dynamics into the waveform are ignored. Or to avoid estimation error, the insulation resistance must be known in advance to carry out parameter calibration. In this work, one parasitic capacitance is applied in the circuit model and employ a new adaptive algorithm based on Lyapunov stability to estimate the insulation resistance. This new online monitoring method and circuit are verified through simulation and experimentation, respectively. The results demonstrate that the proposed method can quickly react and track variations of insulation resistance on both positive and negative DC lines. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1882-1887, 2017 [ABSTRACT FROM AUTHOR]

Copyright of Electrical Engineering & Electromechanics is the property of National Technical University, Kharkiv Polytechnic Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to evaluate the functionality of an insulating vegetable oil (natural ester) in electric transformers, comparative electric measurements were performed on a 30 /0.4 kV-40 kVA transformer. During the operation of the transformer filled with commercial mineral, the main electrical characteristics were determined, namely: applied voltage test (according to IEC 60076-3: 2013), measurement of partial discharges (according to IEC 60270: 2015), measurement of capacities and of delta tangent (according to IEC 60076-1: 2011) as well as of insulation resistance (according to IEC 60076-1: 2011). These parameters were also determined under the same conditions on the transformer filled with an experimental vegetable oil. The comparative measurements have highlighted the fact that, from the point of view of the applied voltage test (2 kV/rms) and of partial discharges, there are no differences in the behaviour of the two investigated oils. Determination of dielectric losses indicated that when using vegetable oil, tgδ = 3.94 % these are substantially lower than the investigated mineral oil (tgδ = 8.18 %).The measurement of dielectric losses show ed that they are significantly lower when using vegetable oil (tgδ = 3.94 %) than in the case of the investigated mineral oil (tgδ = 8.18 %). In addition, it was found that the insulation resistance when operating the electric transformer with vegetable oil is 2.5 times higher than in the case of mineral oil. [ABSTRACT FROM AUTHOR]

To improve the accuracy of insulation monitoring between the battery pack and chassis of electric vehicles, we established a serial battery pack model composed of first-order resistor-capacitor (RC) circuit battery cells. We then designed a low-voltage, low-frequency insulation monitoring model based on this serial battery pack model. An extended Kalman filter (EKF) was designed for this non-linear system to filter the measured results, thus mitigating the influence of noise. Experimental and simulation results show that the proposed monitoring model and extended Kalman filtering algorithm for insulation resistance monitoring present satisfactory estimation accuracy and robustness. [ABSTRACT FROM AUTHOR]

The integrity of instrumentation cables is an important performance parameter in the brazing process, along with the sealing performance. In this paper, an accurate control scheme for brazing of the instrumentation feedthrough in a vacuum induction brazing system was developed. The experimental results show that the accurate brazing temperature control performance is achieved by the developed control scheme. It is demonstrated that the sealing performances of the instrumentation feedthrough and the integrity of the instrumentation cables are to be acceptable after brazing. [ABSTRACT FROM PUBLISHER]

In order to assess the behavior and lifetime of some metallic pipelines (made with steel pipelines insulated with heat applied polyethylene foil) buried in the ground with medium chemical aggressivity (resistivity between 20 and 45 Ω · m) and with predominant mold species Trichoderma viridae, Aspergillus niger and Chaetomium globosum, two underground metallic pipelines have been monitored (for 146 months) through periodic measurements of insulation resistances. Field measurements have been revealed that during operating, the investigated pipelines are disturbed with alternative voltages ranging from 3.1 and 7.4Vrms. It was also found that in given operating conditions, the specific electrical coating resistance Rsc decreases over time t [months] taking account of relation Rsc [108Ωm2] = -0,0001t2 - 0,0325t + 75,52 - indicating an insulation lifetime of 87 years. [ABSTRACT FROM AUTHOR]

The insulation level of DC control circuits is an important safety-critical factor and, thus, should be subject to continuous and periodic monitoring. The methods used for monitoring the insulation in live circuits may, however, disturb the reliable operation of control relays. The risks of misoperation and failure to reset of relays posed by the operation of various insulation monitoring and fault location systems are evaluated. [ABSTRACT FROM AUTHOR]

Polycrystalline BaTiO3-Bi(Zn1/2Ti1/2)O3 ( BT- BZT) ceramics have superior dielectric properties for high-temperature and high-energy density applications as compared to the existing materials. While it has been shown that the addition of BZT to BT leads to an improvement in resistivity by two orders of magnitude, in this study impedance spectroscopy is used to demonstrate a novel change in conduction mechanism. While nominally undoped BT exhibits extrinsic-like p-type conduction, it is reported that BT- BZT ceramics exhibit intrinsic n-type conduction using atmosphere-dependent conductivity measurements. Annealing studies and Seebeck measurements were performed and confirmed this result. For BT, resistivity values were higher for samples annealed in nitrogen as compared to oxygen, whereas the opposite responses were observed for BZT-containing solid solutions. This suggests a fundamental change in the defect equilibrium conditions upon the addition of BZT to the solid solution that lowered the carrier concentration and changed the sign of the majority charge carrier. This is then also linked to the observed improvement in resistivity in BT- BZT ceramics as compared to undoped BT. [ABSTRACT FROM AUTHOR]

Copyright of Electrical Engineering & Electromechanics is the property of National Technical University, Kharkiv Polytechnic Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electrical Engineering & Electromechanics is the property of National Technical University, Kharkiv Polytechnic Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To ensure the stable operation of Experimental Advanced Superconducting Tokamak (EAST) fast control power supply, a new alternating current insulation monitoring technique is presented in this Letter which is suitable for the high‐frequency and high‐voltage working environment of EAST fast control power supply. The method uses alternately switching resistance in an unbalanced bridge to change the voltage, and detects the voltage in real time, then calculates the insulation resistance. The simulation platform based on Simulink was built to carry out real‐time insulation monitoring analysis of EAST fast control power supply as voltage input, the waveforms of which were consistent with the expected. Through experimental verification, the new method can work well for EAST fast control power supply. [ABSTRACT FROM AUTHOR]

High energy density capacitor is a key device in pulse power system such as Electromagnetic Gun system and Laser Fusion system. The increase of energy density of capacitor is beneficial from emerge of metallized technology in electrode and advancement in manufacturing. In this paper, first, the influences of different temperature, electric field strength and Ω/square on the insulation resistance and voltage drop are compared for proper use of capacitor and for manufacture improvement purpose. Then, influences of different charging rate and temperature on capacitor are compared for selecting a reasonable charging method. A capacitor is united by several metallized capacitors with series or parallel connection. The arrangement method and the difference of circumstance result in the temperature difference among the capacitors and influence the characteristics of capacitor. The test with two series capacitor be charged under different temperature indicates that the difference of temperature results in the difference of the voltage distribution. The difference is greater as the temperature increase. The results of the test also show that the time of charge is an important factor which influences the voltage of the capacitor obviously. [ABSTRACT FROM AUTHOR]

Copyright of Electrical Engineering & Electromechanics is the property of National Technical University, Kharkiv Polytechnic Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper investigates on dielectric condition assessment of high power Insulated Gate Bipolar Transistor (IGBT) modules through modern dielectric and diagnostic test methods. Two groups of IGBT samples (new and aged) are selected for this purpose. The new IGBT samples are grouped as 'set-1/virgin' and marked as 'A', 'B', 'C', 'D' and 'E' respectively. Amongst all, a fault (electric puncture) is introduced into the sample 'E'. The samples 'A' and 'B' are maintained virgin while samples 'C', 'D' and 'E' are subjected to partial discharge measurements as recommended by IEC60270. The samples are qualitatively ranked based on their PD level. Subsequently, the dielectric condition of each sample is measured and analyzed over a wide span and frequency. Following this, similar experiments are carried out on IGBT samples that were aged under service and their behaviour over a wide frequency is analyzed. In conclusion, the present study might provide an opportunity in improvement of diagnostic and quality control test methods that are currently exercised on IGBT modules and power conversion devices. Also, these findings enable discrimination of electrical discharges caused by IGBT modules in power conversion equipments which might help in accurate determination of their dielectric condition and reliability. [ABSTRACT FROM PUBLISHER]

The presence of Corrosive sulphur in mineral transformer oil affects the performance of insulation system of transformers. In this paper results of experimental investigations carried out on voltage current characteristics and insulation resistance of paper oil insulation in presence of copper sulphide are presented and discussed. A model for copper sulphide migration is proposed to explain the increase in leakage current and reduction in insulation resistance. Existence of two regions in voltagecurrent characteristics, one dependent on the insulation properties of paper oil insulation and other due to semi-conducting copper sulphide is discussed and explained. [ABSTRACT FROM AUTHOR]

Ambient and test conditions can affect the analysis results of the insulation system testing in high voltage (HV) electrical machines. In this context, insulation resistance (IR) and polarization index (PI) are two common techniques for winding insulation assessment in offline mode. This paper investigates the influence of main parameters that affects IR/PI tests results. Temperature, humidity, and pressure are the wellknown environmental parameters which could affect dielectric parameters of insulation such as IR and PI. On the other side, test voltage level and voltage polarities connections are two prominent factors in sampling the resistance during the test. Moreover, the insulation resistance value depends on the type of fault and its severity. The variations of insulation resistance with considering the mentioned parameters are evaluated in this paper, to study the possible correlation between IR/PI and changes in other parameters. It was found that with taking the effective parameters into account, the accurate and reliable insulation test interpretation can be achieved in HV electrical machines. A comprehensive review of literature was done and industry experts were surveyed for their ideas and experience under a research project. The main results are summarized in this paper. [ABSTRACT FROM AUTHOR]

The article discusses the state of transformer insulation. For a more accurate determination of the transformer insulation state are used three methods. The measurement of insulation resistance is the basic method and is set in the standard, value demonstrates the state of total insulation of transformer. Because the determination of moisture content of the paper insulation of transformer is very difficult process and it is necessary take a sample of paper, in this case is used method of return voltage. Return voltage measurement is more complex method and in many cases is determine a clear result very difficult. For evaluation of results have mainly impact moisture content and degree of aging of paper insulation and of course, content of conductive impurities in oil. Because the moisture content in oil is much lower than in the paper, return voltage measurement is used to determine the moisture content in paper insulation only. To confirm the results of return voltage measurement is used frequency domain spectroscopy, which clearly, according computational model, calculates the moisture content in the paper insulation. [ABSTRACT FROM AUTHOR]