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This paper reviews the phasor and directions of a single-phase-ground fault current (s) in a high-resistance grounded (HRG) power system. A brief review of the published literature, which is inconsistent, has caused confusion on what should be the correct phasor and fault current directions to be used in dot standard P3003.1. An application concept that during single-phase-ground fault condition, “distributed capacitive current direction reverses in the two un-faulted phases” compared to the direction under normal system operation. This concept has been applied before [2] [6]; however, some application engineers raised the question on this concept. The concept is currently used in the modern ground fault protection relays used for HRG and ungrounded power systems. It has no impact on the operation of the power system during the phase-ground fault condition, but it helps in providing ground-fault current flow from faulted location to ground, a normal industry convention. The paper will provide guidance on how to update the contents of the HRG system contained in the current edition of IEEE STD. 142 to be used for Dot Standard P3003.1 [23].

Most of the Shearer adopt additional DC power protection, it has to protect a comprehensive, capacitive current compensation, the simple characteristics of action value of the tuning, however, it in the actual production will occur leakage protection device malfunction, tripping phenomenon For the leakage protection circuit in traction motor of coal winning machine is impacted by frequency converter devices in the course of their work, malfunctions appear frequently. This paper makes an in-depth analysis, analyzing the shortcomings of the current protection circuit, After the analysis of the interference signal, it is proposes a solution of using the subtraction circuit to offset interference signals and conducts a simulation analysis. The above scheme, which is simple and easily realized, can improve the reliability of leakage protection device in traction motor. Avoiding unnecessary production halts. The production efficiency can be improved.

Recently, electric power equipments insulated by epoxy resins have been accident-filled, so that we have been interested in the degradation character of epoxy resin insulations at normal temperature to estimate their life. Thus the aging tests on epoxy insulations were accomplished, and then resistive leakage current on their insulations kept in a glass state at 90 and 80°C was measured by the method canceling capacitive current which was applied to degradation estimation of ZnO varistors. Results of reduced resistive leakage current were led to evaporation and migration of hydrogen ions in epoxy insulations, which are compared between new ones and used ones and applied to estimation of aging degradation in this paper.

The grounding capacitive current is one of the most important parameters of ungrounded neutral system. Usually this parameter is obtained with the method of additional capacitor or metal grounding. However, the former is complicated and the additional capacitor has negative effects on measurement results, and the later is dangerous when used in testing. In view of that, the paper proposes a new method to calculate grounding capacitance current based on the data of single-phase-grounding faults in power system with indirectly earthed neutral. This method reduces the error by using the least-square method .The ATP simulation results show that this method is accurate basically.

Digital filtering algorithm is utilized for gathering data of MOA tester by least square method. The interphase interference is analyzed. With the combination of third harmonic wave, the algorithm is proposed about the third harmonic resistive current and capacitive current. Finally the circuit and hardware part is designed.

In this paper, the IrO2 electrode preparation technique consisting in thermal treatment of pure Ir in air was used in order to produce an IrO2-based microelectrode-array (TOIROF-MEA) with low capacitive background current. The TOIROF-MEA was characterized using Fe(CN)64-/3- as model redox couple. It was found that very low concentrations can be detected; this feature makes TOIROF-MEA suitable for analytical applications. Keywords: Microelectrode-array, IrO2, Capacitive current, Thermal treatment of pure Ir

Underground distribution systems are normally exposed to permanent faults, due to specific construction characteristics. In these systems, visual inspection cannot be performed. In order to enhance service restoration, accurate fault location techniques must be applied. This paper describes an extended impedance-based fault location algorithm for underground distribution systems. The formulation is developed on phase frame and calculates the apparent impedance using only local voltage and current data. The technique also provides an iterative algorithm to compensate the typical capacitive component current of underground cables. Test results are obtained from numerical simulations using a real underground distribution feeder data from the Electrical Energy Distribution State Company of Rio Grande do Sul (CEEE-D), southern Brazil. Comparative results show the techniques accuracy and robustness in respect to fault type, distance and resistance.

This paper presents the optimal design of a SF6 gas circuit breaker to improve the capacitive current interrupting performance. The objective function for the optimization is the minimal difference between the breakdown voltage and the applied voltage. To obtain the dynamic gas properties, the axisymmetric Euler equation is solved using the finite volume fluid in cell method. Breakdown voltage is calculated using the empirical equation, which is a function of the gas density and the electric field intensity. To facilitate the optimization process, which is computationally intensive, the Kriging model is employed as an approximation model. A sequential approximation technique is developed to improve the accuracy of the Kriging model and to reduce the number of real function calls. The developed optimization technique was applied to the design of a 145-kV gas circuit breaker. It was verified that the optimized circuit breaker has better interrupting performance than the original model.

This review aims to summarize the current state of research concern- ing the interaction of electrodes with liposomes suspended in solutions. Main at- tention is given to the complex mechanism of adhesion and spreading of liposomes on mercury electrodes. That mechanism can be studied with the help of chronoam- perometry, where each adhesion-spreading event appears as a capacitive current spike. Integration of these spikes produces charge versus time transients that can be modeled and simulated, revealing the details of the multi-step adhesion-spread- ing process. Whereas the number of spikes per time mirrors the macro-kinetics, the analysis of the time behavior of each spike mirrors the micro-kinetics of each adhesion-spreading event. The reviewed studies show that this approach provides a new tool to study the properties of liposome membranes. The adhesion-spreading of liposomes on mercury electrodes has strong similarities to the process of vesicle fusion, which makes these studies a biomimetic model allowing one to deduce the effects of foreign molecules in bilayer membranes.

Inverters with capacitive loads or with additional series capacity and which assure a capacitive current through series circuit usually determine observance of return time, and reactive power delivered by load is adequate for commutation of thyristors, not be necessary auxiliary turn-off circuit. These types of inverters are known below name inverters with load commutation.

Understanding the behaviour of space-charge between two electrodes is important for a number of applications. The Shockley-Ramo theorem and equivalent circuit models are useful for this; however, fundamental questions of the microscopic nature of the space-charge remain, including the meaning of capacitance and its evolution into a bulk property. Here we show that the microscopic details of the space-charge in terms of resistance and capacitance evolve in a parallel topology to give the macroscopic behaviour via a charge-based circuit or electric-field-based circuit. We describe two approaches to this problem, both of which are based on energy conservation: the energy-to-current transformation rule and an energy-equivalence-based definition of capacitance. We identify a significant capacitive current due to the rate of change of the capacitance. Further analysis shows that Shockley-Ramo theorem does not apply with a time-varying applied bias and an additional electric-field-based current is identified to describe the resulting motion of the space-charge. Our results and approach provide a facile platform for a comprehensive understanding of the behaviour of space-charge between electrodes.

A new method to assess the condition of metal-oxide surge arresters is presented. The fundamental component of the resistive current is used as an indicator. This current is obtained by exploiting the linear relationship, which exists between the peak value of the fundamental component of the resistive current and the phase shift between the fundamental components of the capacitive current and the total arrester current. This relationship is independent of temperature for a given type of arrester. Results are presented to demonstrate the accuracy and the reliability of the new technique.

An artificial neural network (ANN) model has been developed for tensammetric determination of a series of Brijes (Brij 30, Brij 35, Brij 56, Brij 96) as nonionic surfactants. The tensammetric method is based on the measurement of the capacitive current of the mercury electrode after adsorption of surfactants. All Brijes were analyzed in the concentration range of 1.0–100.0 μg mL−1. The proposed method shows good sensitivity and applicability to the simultaneous determination of mixtures of four Brijes in aqueous solutions.

Several ways for monitoring the soundness of ZnO lightning arresters have been suggested, and all of which are based on the measurement of leakage current since it is well known that the resistive leakage current is a main indicator of arrester deterioration. In this paper, we proposed an algorithm to measure the resistive leakage current, which is quite different from the conventional method that eliminates capacitive current from the total leakage current. The proposed algorithm is based on that the magnitudes of the resistive leakage current are equal at the same applied voltage levels. To confirm the reliability of the algorithm, we fabricated a leakage current detector and designed an analysis program. Experimental results showed that the method does not need a complex circuitry and is useful to analyze the resistive leakage current.

This paper describes the capacitive current interruption capability of circuit breakers from the viewpoint of flashover characteristics between the contacts of breakers. The authors obtained flashover characteristics between the contacts having a short gap between them by comparing the data for new contacts and the data for contacts eroded after having been exposed to three interruptions at T60 according to amended regulations JEC 2300 (1998) and IEC 62271-100 (2001). Comparison of the flashover characteristics and the electric field calculations obtained by measurements using new and eroded contacts have shown that the deterioration of dielectric strength amounts to 10 to 20%. The authors also conducted flashover tests for the contacts and nozzle after a significant number of interruptions. The total number of interruptions can be considered as the maximum possible number of interruptions according to CIGRE research. The deterioration of dielectric characteristics is 10 to 30%. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(1): 28–37, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10281

Cyclic voltammetry and surface analysis techniques (EDX microanalysis, mapping of elements and SEM images) have been used to study the solid state reactions of Ir in blank solution or Hg(I)-containing solution. The studies in KNO3/HNO3 solution permit to suggest the formation of a thin oxide layer film deposited in the substrate. The RCV process exhibits the decrease of capacitive current associated to the substrate surface restructuring. The electro deposition of Hg occurs initially in UPD condition from Hg(I)-containing solution, CHg(I) = 3.51x10 -7 mol L -1 . The electro deposition of bulk mercury occurs from Hg(I)-containing solution, CHg(I) = 3.51x10 -5 mol L -1 . It was observed the deposition of Hg in the substrate in open circuit for all employed conditions.

The depth of location of electrochrome dyes RH-type in a bilayer is evaluated using the magnitudes of intramembrane field Δ ϕ measured by two methods: from relative change of the rate of transmembrane transport of hydrophobic ions and by means of electrostriction method based on the compensation of the 2nd harmonic of capacitive current, which is generated due to electrostriction phenomenon if sine voltage is applied to the bilayer. The experiments and theoretical analysis are conducted. Comparing the theoretical curves for Δ ϕ measured by the both methods and the experimental data, the depth of location was estimated as follows: 0.7–1 nm for the dyes RH-421 and RH-160, and 0.9–1.15 nm for the dye RH-237.

Under light loading conditions of networks, steady overvoltages can result. This is because at low loading there is not enough consumption of reactive power generated by the lines, with the consequence that excessive capacitive current flows in the system, and active power losses become high. Ultimately, this leads to increased costs of supply which have to be borne by customers. In this paper the authors have investigated the feasibility of using step down transformers in derating operating voltages of lines in a load centre as a potential solution for resolving overvoltages. These transformers are placed at the ends of a corridor, thereby derating the operating voltages of the lines between them. Loadflows were carried out for cases without (Case A) and with (Case B) the step down transformers. The inclusion of step down transformers showed a decrease in the reactive power flow in the lines, lesser steady voltages, and a reduction in active power losses. The proposed use of step down transformers is thus a feasible solution for solving steady overvoltage concerns and should be considered among other options when such problems arise.

A simple linear electromechanical model for an electrostatically driven resonating cantilever is derived. The model has been developed in order to determine dynamic quantities such as the capacitive current flowing through the cantilever-driver system at the resonance frequency, and it allows us to calculate static magnitudes such as position and voltage of collapse or the voltage versus deflection characteristic. The model is used to demonstrate the theoretical sensitivity on the attogram scale of a mass sensor based on a nanometre-scale cantilever, and to analyse the effect of an extra feedback loop in the control circuit to increase the Q factor.

Speed of nerve impulse conduction is greatly increased by myelin, a multi-layered membranous sheath surrounding axons. Myelinated axons are ubiquitous among the vertebrates, but relatively rare among invertebrates. Electron microscopy of calanoid copepods using rapid cryofixation techniques revealed the widespread presence of myelinated axons. Myelin sheaths of up to 60 layers were found around both sensory and motor axons of the first antenna and interneurons of the ventral nerve cord. Except at nodes, individual lamellae appeared to be continuous and circular, without seams, as opposed to the spiral structure of vertebrate and annelid myelin. The highly organized myelin was characterized by the complete exclusion of cytoplasm from the intracellular spaces of the cell generating it. In regions of compaction, extracytoplasmic space was also eliminated. Focal or fenestration nodes, rather than circumferential ones, were locally common. Myelin lamellae terminated in stepwise fashion at these nodes, appearing to fuse with the axolemma or adjacent myelin lamellae. As with vertebrate myelin, copepod sheaths are designed to minimize both resistive and capacitive current flow through the internodal membrane, greatly speeding nerve impulse conduction. Copepod myelin differs from that of any other group described, while sharing features of every group.

The paper is focused on the operational experience with an automatic system for suppression of a fault current during a ground fault by the additional earthing of the faulted phase in a supply substation. Such system was experimentally installed in the Brno-Medlanky 110/22 kV substation. To verify the benefits of the system as well as to assess its possible failings, twenty-four experimental measurements based on a theoretical study were performed. During those experiments, low-resistance and arc ground faults were monitored in the urban and suburban part of the compensated network with a capacitive current of 300 A and 800 A. The results of the crucial experiments and the evaluation of the system functioning are summed up in the final part of the paper.

An after-laying test is required to demonstrate the soundness of XLPE underground cable lines with joints. AC voltage application is desirable for the test; however, the equipment for ac application must be very large because it must supply large capacitive current for cables. DC voltage is normally applied, which can be supplied with small equipment; however, the effectiveness of the dc application is questioned because the electrical stress distribution is quite different from that with ac application and, moreover, dc application could damage insulation properties of cables. The authors targeted the Oscillating Wave (OSW) method and the Very Low-Frequency (VLF) method as alternative after-laying tests. They first developed modeling methods of various defects on underground cable lines and applied OSW and VLF to these defect models. They found that OSW and VLF methods have higher fault detection capability than dc voltage application. They also demonstrated that the defects which can be easily detected with the OSW method are difficult to detect with the VLF method and vice versa. They showed that serial application of both methods highly improve the fault detection ability for XLPE underground cable lines.

This paper presents an extended formulation for fault location on electric distribution systems based on one-terminal measurement of apparent impedance. The method is developed using phase-components analysis to account for the inherent unbalanced operation of distribution feeders. Since distribution loads present a stochastic variation through time, a technique for compensation of load variation in both magnitude and angle is also presented. The proposed developments include two general fault location equations that account for any fault type. An iterative algorithm to compensate the line capacitive current component is also provided, thus enabling the application of the technique to long rural and underground systems, in addition to overhead distribution systems. Test results show the accuracy and robustness of the fault location algorithm to different fault types, distances and resistances, considering system's load profile variations up to ± 50%.

In order to study operational features of resonant grounded system deeply, and test all performance indexes of the control device of arc-suppression coil, this paper comes up with the research ideas and implementation of the low-voltage simulation environment, describing its technology parameters and building principles of the major parts in detail. Functional tests on control device of the arcsuppression coil have been down, including capacitive current measurement, automatic resonance, automatic tracking, singlephase grounding and so on, guiding the work on the research and development of the arc-suppression coil.

The low‐level leakage currents in thin silicon oxide films were measured before and after the oxides had been stressed at high voltages. Four components of current were identified. These components were the tunneling current, the capacitive current associated with the measurement sweep rate, a negative differential current associated with the voltage sweep through the changing oxide C‐V characteristic, and an excess current that occurred after the high‐voltage stress. The excess current was due to the charging and discharging of traps generated inside of the oxide by the high‐voltage stress. The excess current was proportional to the number of traps generated in the oxide. The magnitude of the excess current could be changed by changes in the measurement procedures due to the charging and discharging of traps. A major portion of the stress‐generated excess low‐level leakage current may not be a current that flowed through the oxide, but may be a trap charging/discharging current. This paper will concentra...

There are AC filters in the HVDC substation; it is possible that extremely high recovery voltage occurs when the AC filters are switched with circuit-breaker. So some special requirement is put forward to circuit-breaker, which is the circuit-breaker must break small capacitive current with very low probability of restrike and very high recovery voltage. In this paper, we analyze the electric intensity and gas density of the key position during the process of recovery voltage rising by means of the finite element analysis software, and judge the capacitive current breaking capacity of the circuit-breaker that will be used to switch 800kV AC filters. Basing on the result of analysis, we adjust the velocity of opening, the shape of contactor or number of break series in one pole etc which is the influential factor of breaking capacity and repeat the analysis until the result meet the requirement of capacitive current breaking in theory.

Based on the characteristics of the rectifiers with near sinusoidal input currents (RNSIC-1, with capacitors connected on the DC side and RNSIC-2, with capacitors connected on the AC side), the paper proposes a comparative analysis between the performances of the two variants of RNSIC converters with three-phase six pulse full-bridge diode rectifiers with passive filters. A comparative analysis between the performances (efficiency and generated capacitive current) of the two variants of RNSIC converters with three-phase six pulse full-bridge diode rectifiers with passive filters is presented. Therefore, the technical and economical advantages of the RNSIC converters are demonstrated. The inductors and the capacitors of the RNSIC converters do not belong to the category of resonant circuits tuned to specific frequency.

A series of experiments on the capacitive current interruption using an air-break disconnector (DS) with an Auxiliary Interrupter (AI) is presented. The AI contacts open with much higher speed (average llm/s) than the main contacts of the DS (0.2-0.6m/s). This paper mainly focuses on optical observation of the arc recorded by a high-speed camera. The result shows: (i) The arc brightness is synchronous with the arc current; (ii) The arc brightness increases with the higher current level to be interrupted I d ; (iii) With higher I d , the afterglow of the arc remnants decay slower.

Arc-suppression coil is a widely used apparatus in 10-35KV level power network,which is a controllable reactor essentially and the reactance of the Arc-suppression coil can be regulated accordantly with the variety of capacitive current. The paper proposes a new Arc-suppression coil excited by AC current and analyzes characteristics of the coil by means of simulation and experiment, also gets some useful conclusions that will provide references for the future application.

Instantaneous feedback control technology has obtained the widespread application in the domain of power electronics. This paper conducts the contrast study between single voltage instantaneous feedback control technology and the Dual-loop voltage Feedback Control technology based on Capacitive Current Inner-loop. Taking the PWM inverter as research object, analysis and research is made about the PWM inversion system on the basis of two different control modes. The dynamic response of single voltage instantaneous control is slow with worse stability. In contrast, not only can the dual-loop feedback control enhance the stability and the anti-disturbance capacity of the system, but also it can improve dynamic property of the system with good quality of the inverter output voltage as well as low harmonic content. This paper verifies the applicability and reliability of the dual-loop feedback control technology by Saber simulation and experimental test.

High-speed opening auxiliary contacts ("whip type device") is used to enhance the capacitive current interruption capability of air-break disconnectors. Firstly the paper introduces the basic working principle of this device. Secondly a series of laboratory tests are described. The voltages at both sides of the disconnector and the current through the disconnector are measured. The arc images are recorded by a high-speed camera with 1000 frames/s as well. The test data and arc images are studied for both failed- and successful interruptions. Finally, conclusions and remarks are given.

The tensammograms of several sets of cationic polyacrylamide copolymers are discussed and compared. Tensammograms are not affected by molecular weight, but plots of capacitive current at a chosen potential versus charge density give regular curves. Key words: tensammetry, cationic, polyacrylamide, charge density.

Restrike characteristics on a capacitive current breaking in a vacuum have been investigated. In a small capacitive current breaking test, double voltage from commercial voltage (peak) would be applied between contacts of a VI. The configuration of contacts and the current conditioning dependence of VI practical samples with axial magnetic field contacts were investigated under a simulated capacitive current breaking test. Minimum restrike voltage decreased and voltage dispersion was high due to the presence of slits on the contacts. On the other hand, the minimum restrike voltage increased and restrike voltage dispersion was low due to current conditioning. By practical tests and standardized tests, a new 72 kV VI and dry air insulated VCB has been developed.

In order to study the influence on harmonic characteristics of distribution network with renewable energy, a simplified model of distribution network is established to analyse theory while considering the influence of cable on the system capacitive current. Establishing an actual distribution network model by Digsilent to research the harmonic characteristics impact when photovoltaic power with PV incorporated the distribution network in a variety of different access , while using constant current source model as harmonic source model which often been used in engineering practices. The simulation results show that: optimizing the access location and dispersion of PV can decrease the waveform distortion levels in distribution network and a certain number of high-order harmonic will magnify by a specific grid structure, deteriorating the distribution network power quality.

This paper is designed according to Chinese Standard of GB151665-94, GB110022, GB3988.2, and GB1661.1~5. The rated voltages are 3~35 kV. The rated currents are 12.5~200 A. The interrupting currents are for capacitive current 20-50 times of rated current and for inductive current 3.15~40 kA. The paper gives design processing of high voltage vacuum type hybrid current limiting fuses for double protection characteristics.

Absence of gradients and nernstian equilibrium stripping (AGNES) is a new electroanalytical technique designed to determine free heavy metal ion concentrations in solutions. AGNES had been applied, up to date, with conventional equipment such as the hanging mercury drop electrode (HMDE). Due to their much smaller volume, microelectrodes can reach a given preconcentration factor within a much shorter deposition time, so their use for AGNES has been evaluated in this work. For the particular case of the mercury microelectrode deposited onto an Ir disk (radius around 5 μm), AGNES has been successfully used for speciation purposes in the system Pb + PDCA (pyridinedicarboxylic acid). However, due to a relatively large capacitive current, which decays slowly, the limit of quantification for such microelectrodes has only been reduced by one half with respect to that of the HMDE.

The technological core of automatic compensation arc-suppression equipments lies in the accurate tracing and measuring of system capacitive current to earth. In view of the limitation in present testing methods of capacitive current, a novel measuring and controlling method, which takes the impact of system damping rate into consideration, is proposed and then the method for two extinction coils operating in parallel is obtained. Based on this method, a controller for automatic compensation arc-suppression equipment is developed centering on PC 104 industrial controlling computer. Simulation tests shows that the method proposed in this paper can effectively improve the measuring precision of system capacitive current to earth. (6 pages)

Flow electrification in power transformers has been studied for the last 30 years, since the charge generation phenomenon was suspected to be responsible for power transformer failures. An experimental set-up has been built at the University of Poitiers in partnership with EDF (French utility) to simulate the oil path along the pressboard between transformer windings. The accumulated charge in a pressboard duct can then be estimated by the integration of the measured capacitive current up to infinite time. Among the investigations to reduce the electrostatic hazard, a chemical salt has been injected into new and aged oil at different concentrations. It was found that the accumulated charge was drastically reduced at different salt concentrations for both oils whatever the temperature and the flow rate applied.

Water trees, a type of deterioration that develops in high voltage cable insulation in a humid environment, introduce harmonic distortion in the waveform of the loss current component of the capacitive current of cable insulation. The measurements of the total harmonic distortion could be used as a diagnostic tool to assess the operating conditions of power cables, in particular polymeric-type cables, and their remaining insulation life. A current-comparator technique to accurately measure the total harmonic distortion, including test results obtained on laboratory-aged specimens and short lengths of field-aged cables containing water trees, is presented.