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A renewed interest for dc breakers has evolved owing to the visions of connecting several HVDC links into a HVDC grid. Several breaker concepts have been presented and some also have been implemented and tested. A new approach is proposed in this paper. The fundamental principle is to take advantage of the fast recovery of the voltage withstand capability in a Vacuum Interrupter (VI) when the current is temporarily forced to zero using a low-voltage power electronic converter. The latter excites an oscillating current in a passive resonant circuit during the time interval needed to mechanically separate the contacts in the interrupter. The sum of the line current (to be interrupted) and the oscillating current passes through the vacuum interrupter and experiences zero-crossings when the amplitude of the oscillating current exceeds the line current. The most important benefit of the proposed concept is that a favorable cost can be achieved, because excitation of the oscillating current only requires a low output voltage (compared to the breaking voltage across the VI terminals) from the converter. The total voltage rating of the semiconductors in the latter therefore is only a fraction of that needed in a hybrid HVDC breaker and, additionally, they are not requested to turn off the main current but rather to commutate close to current zero-crossings. Experimental verification of the concept has been performed with current up to 1.6 kA against 1.2 kV.

The current interruption capacity of gas gap can be enhanced by series connecting with vacuum gap in hybrid circuit breaker. For the purpose of compensating the inferior interruption performance of CO 2 gas gap, as the substitute for SF 6 gas gap, the interruption principle and the dielectric strength recovery process of the series gaps of vacuum gap and CO 2 gas gap are studied in this paper. Based on the established test prototype, tests are carried on series gaps to investigate the influences of various arcing times, voltage-dividing capacitor, and CO 2 gas pressure on its interruption performance via synthetic test circuit system. The test results convey that, CO 2 gas gap with gas pressure at 0.8 Mpa can recover its dielectric strength faster and withstand higher recovery voltage under the effect of voltage-dividing capacitor while vacuum gap undertakes initial transient recovery voltage. But limited by the simple structure of gas interrupter and the interruption performance of CO 2 gas, CO 2 gas can't recover its dielectric strength rapidly.

The Redlich-Kwong state equation of the real gas and the governing equations of the flow field were combined to solve the problem. The distribution of physical parameters of the interrupter was attained under the condition of the circuit breaker in small capacitive current interruption by analysis of the 126kV capacitor group SF 6 gas circuit breaker arc extinguishing chamber in air flow field, which is according to enthalpy flow arc model and dynamic model of non-equilibrium arc energy built by microscopic parameters of plasma. The dielectric recovery characteristic curves in arc contacts after the arc extinguished were attained through the coupling calculation in the field of electric and gas flow. Calculation results show that: When the circuit breaker is opening the small capacitive current, the effect of breaking speed on arc burning time is very small and arc extinguished in advance. The arc gap conductivity is about 700S/m, and the thermal conductivity is about 1.1W/m-K at arc extinguishing time. The transient recovery voltage is always lower than that of the breakdown voltage, and the electric arc can successfully break without reburning. To make the short arcing time have a large arc distance, and the large nozzle should be open enough to be strong for the gas blowing condition, the optimum opening speed is 9.6m/s.

Arc faults are a fire-safety risk in both AC (alternating current) and DC wiring, but reliable detection of arc faults and determining the appropriate response is particularly difficult in DC plug-load circuits. This paper presents the development of AFCI testing for DC circuits operating at 24–80 volts. Protecting these circuits from arcing is more difficult than the more prevalent Photovoltaic circuits because of the diversity of loads that may be present. The AFCI testing described in this paper will allow us to identify an effective method to determine DC arcing occurrence. Once identified, an interrupter may then be designed to adequately eliminate the arc. Laboratory test setup and equipment for identifying DC arc will be detailed in this paper. Different scenarios for DC arcing occurrences in the development of the lab test setup will be explained. Several test results of the developed testing tool will also be presented.

When medium-voltage reduced-voltage autotransformer (RVAT) motor starters fail, also referred to as Korndorfer starters, particularly ones in which there is no clear failure to the core or tap-to-tap but just layer-to-layer deep down in the windings, the results are almost always catastrophic. An offshore platform is used as an example to discuss site-specific solutions that are based on the recently developed switching transient analysis, sweep frequency-response analysis, and state-of-the-art electromagnetic transient program (EMTP) simulation techniques. This paper will explain how the power system, interrupter, and transformer interact and outline the steps to solve this long-standing problem as well as present the newly applied solutions. Since the implementation of these new solutions, no further failures have occurred.

The IntelliRupter® PulseCloser® Fault Interrupter offers a gentler alternative to traditional reclosing, reducing the stress on network components and the risk of damage to the 132/11 kV primary substation power transformer, while using just 5% of the energy. Examples of deployment in Chattanooga, USA, and in Birmingham, UK, show how the IntelliRupter® PulseCloser® Fault Interrupter can play a vital role in the wide-scale deployment of smart grids and extending asset life.

In the minds of people health has been a very important parameter, so a monitoring system is required to keep them alert about their health. Monitoring systems are also required in Intensive Care Unit of various hospitals. Hospital staff faces difficulty in handling devices due to their bulkiness and huge number of wires while giving medication to the patient. Monitoring system requirement is of very small size and low power operation. A small size, wearable device is presented in this paper, which consists of PSoC 4, photo interrupter and a very small size Bluetooth module. The system is totally wireless due to the use of Bluetooth module. Different sensors used are attached on the wrist for experimentation. Photo interrupter is used to read the data in the form of analog signal which is further amplified and converted to digital signal by ADC present in PSoC controller. PSoC is used mainly to reduce the system size, as both analog and digital peripherals are available inside a single chip. Due to this the discrete analog components such as OpAmp, ADC and Filter are reduced. Analog signal obtained from sensor is processed by the controller and the values of Heart Rate (Pulse wave) and Temperature are calculated. Temperature is obtained using the LM35 sensor. Total system is mounted on a PCB and sensors are taken out with the help of wires. The PCB design is embedded in a black box. System operates on 3.3V and current requirement is less that 50mA, as the deep sleep mode has been used in both PSoC and Bluetooth. The system is powered by a Lithium Ion battery. A wireless wearable system is built which gives two different parameters of health i.e. heart rate and body temperature. The problem faced by doctors and nurses can be reduced by using this small size and wireless device.

In commercial medium-voltage vacuum contactors, widely used for grid management, the linear motion required for the actuation of contacts is often generated by a linear actuator. Aiming to investigate alternatives from an industrial point of view, a rotary actuation system based on a switched reluctance motor and a suited coupling mechanism was developed. The design process, based on a mechatronic approach using multi-physics modeling and simulation, is recalled first in this paper. A dedicated test rig designed and assembled for validation purposes is then described. Finally, experimental results obtained by testing the prototype motor and coupling mechanism are presented, confirming the expected performances.

Предметом исследования являются контактные соединения. Объектом исследования являются аналитические критерий браковки контактных соединений. Структурно диссертационная работа состоит из введения, восьми глав, библиографии, приложений. В введении обусловлена актуальность выбранной темы, сформулированы цель и задачи исследования; в семи главах раскрываются те или иные аспекты исследуемой темы; после каждой главы представлены обобщающие выводы по проведенному исследованию, также как в заключении; в библиографии содержится список всех используемых материалов для проведения данного исследования; в приложениях приведен список рассматриваемых выключателей с целью более наглядного представления., The subject of research is the contact connection. Object of research are the analytical criteria of rejection temperature of contact connection. Structurally thesis consists of an introduction, eight chapters, bibliography and applications. The introduction is due to the relevance of the chosen topic, formulated the goal and objectives of the study; In the seven chapter reveals the various aspects of the topic and after each topic presents general conclusions on the studyalso in the conclusion; the bibliography contains a list of all the materials used for this study; applications listed analyzed busbars to better visualize.

In SF6 self-blast interrupters, which are being developed as the next-generation switching mechanism, the arc burns within insulating nozzles with an ablation of the nozzle material and leads to an incoming gas flow for the pressure chamber with a pressure-rise during the high-current phase. Close to current zero, the arc can be cooled down and quenched completely by the reverse gas flow from the chamber to the arcing zone according to the pressure gradient between them. Therefore, the interruption of fault currents is dependent on the thermal decay of arcs during the current-zero phase by the blowing-off force, which is generated by the pressure-rise of the chamber during the high-current phase. In this study, we calculated SF6 arc plasmas caused by fault current interruption inside a SF6 self-blast interrupter using a computational fluid dynamics (CFD) technique and investigated the thermal interruption performance with thermal decay near current zero as well as the switching mechanism of the interrupter with an ablation of the nozzle material.

This paper presents the design and development of a customizable force measurement unit (FMU). The sensing mechanism is based on a monolithic structure incorporating a flexure with an interrupter and photo-sensors. The FMU is able to measure force by the deformation of the flexure, which results in a difference in the intensity of infrared light detected. Owing to the simplicity of the proposed structure and the sensing method, the FMU is an adaptable sensing platform with high design flexibility. We performed finite element method (FEM) simulations to systematically determine a set of design variables and characterized the static and dynamic properties of the fabricated FMU. We demonstrated that the FMU shows comparable performance to a widely used off-the-shelf sensor (Mini45, ATI) and can be used as a compact and accurate force sensor for various applications.

In this study, we calculated the whole arcing history of SF 6 thermal plasmas happened inside a puffer-assisted self-blast chamber during the alternative current interruption process with two different turbulence models. It is very difficult to correctly realize all phenomena happened inside the interrupter using the computational schemes; therefore, we have been trying to simplify the physics related in the problem. Because most flows encountered in the process are turbulent, the ability to predict turbulence for this application is invaluable for the engineer to design the chamber reliably. The objective of this paper is to model turbulence by averaging the unsteadiness of the turbulence, which are called Reynolds averaged Navier–Stokes models, and to compare the results with pressure and temperature field distributions during the whole arcing history. It was found that the two-equation turbulent model predicts bigger mixing of momentum, heat and species on the arc discharge of this interrupter than the zero-equation model does.

The usefulness of popular occlusional heads to extended, time-frequency analysis of post-interrupter respiratory data was tested in this study. A portable mobile interrupter module, designed to acquire (also in telemedical system) raw signals of mouth pressure (Qao) and airflow (Pao), enabled flexible valve operation during normal breathing and flow induced by the airflow generator. The potential for algorithmic development of data processing procedures and hardware limitations of the shutter-type valve by Jaeger and Micro Medical is depicted here. The power spectrum density of Pao and input interrupter impedance (Zint), calculated by the Micro Medical interrupter, were sensitive indices of respiratory mechanics measurement, but problematic natural oscillations and leakage during valve closing reduced the clinical relevance of the assessments. These hardware specifications represent prerequisites for prospective research in a sensing technology domain on an optimal valve-transducer unit design.

The scheme of a superconducting fault current limiter (SFCL) rated for operation in the DC electric networks at the maximum current of 300 A, is proposed. This device incorporates a module based on 2G high-temperature superconductors and a quick-action vacuum DC interrupter. Authors present the investigation results relating both to the current-limiting capacity of DC SFCL and to recovery time of the super-conducting state after current disconnection at the voltage of 3.5 kV.

High-power lasers (>+21dBm), because of their ability to transmit long distance signals, have gradually become the common solution for signal transmission systems including regional cable television, Fiber To The Home (FTTH), and gigabit passive optical networks (GPON). However, if protective design is not implemented at the client-side facility, users may be exposed to health hazards caused by the high-power laser, e.g. direct eye exposure to laser beams. High-power optical adapters with photo-interrupters use metal shutter to prevent direct laser beam exposure to the eyes. They have progressively replaced conventional optical adapters and have entered the market mainstream. Our study uses the elastic-plastic theory together with parametric design to investigate the effect of geometry on the initial photo-interrupter spring-back angle. Once the metal spring-back stabilizes after several attempts of insertion and extraction, the initial springing-back angles are found to be the same as the simulated results. In our study, it is observed that factors including the ratio of the notch width to the total width of the metal shutter plate and the relationship with the boundary conditions have significant influence on the springing-back angle. These can be used as references in design control.

Due to deformation of the cantilever and lock, the MEMS explosion interrupter used in fuze often cannot move properly. An explosion interrupter with improved strength is proposed. The caudal shape of the cantilever is improved and its structure is changing from the straight hook to the bend hook. The thickness and the patulous angle of the lock is enhanced. Simulation results show that the improved caudal shape of the cantilever is not stuck by the baseplate boss and the improved lock could enter into the locker successfully. The explosion interrupter moves in-position under centrifugal force and be locked.

Nowadays, computer simulation of processes during current interruption is widely used in design optimization of HV circuit breakers. A simplified physical enthalpy flow arc models provide possibility to get relatively simple, and easy to use, simulation software for HV SF6 circuit breakers. Such software has been developed and successfully used in development of various SF6 circuit breakers, based on classical puffer and puffer assisted self-compensated principle. General outline of the computer program, as well as some simulation results and their experimental verification obtained on a real 245 kV SF6 circuit breaker, are presented. The interrupter is based on puffer assisted selfcompensated principle where arc energy is used to partly compensate compression forces during high current interruptions. It additionally uses a double speed contact stroke created by a simple mechanism placed below the moving contact.

The arc behavior in the current zero region is critical in the case of very steep rising TRV, such as after clearing a short-line fault. Therefore, intensive and abundant short-line fault tests (L90) of a 245 kV SF6 circuit breaker were performed at the KEMA High Power Laboratory. For the purpose of a comparative analysis three different sets of data were obtained during the tests: 1) High-resolution measurements of near current-zero arc current and voltage were carried out. The current zero measurement system (CZM) works as a standalone system in addition to the standard laboratory data acquisition system. The arc conductance shortly before current zero and the arc voltage extinction peak give a clear indication of the interrupting capability of the breaker under test. 2) From the measured traces of every individual test, arc parameters (3 time constants and 3 cooling-power constants) were extracted for the composite black box arc model, which has been developed by KEMA High Power Laboratory and is based on more than 1000 high-resolution measurements during tests of commercial high-voltage circuit breakers. Its aim is to simulate interruption phenomenon in SF6 gas, evaluate performance of HV SF6 circuit breakers in testing and enable the prediction of the performance under conditions other than those tested. 3) After each test, using specially developed computer software, based on a simplified physical enthalpy flow arc model, the values of the arcing contact distance, gas mass flow through the nozzle throat and pressure inside the compression cylinder were calculated. The values of these characteristic quantities at the current zero are relevant indicators for successful interruption. In the comparative analysis, mathematical relations and statistical correlations between the evaluated parameters of the composite black box arc model and the characteristic output quantities are established and discussed. The link has been verified by MatLAB simulation of every indi- - vidual test. This approach enables acceptable prediction of interruption success in a similar circuit and with a similar interrupter without SLF tests and CZM.

The feasibility of using a magnetodynamic current interrupter for switching multimegaampere current pulses is considered. The operation of the interrupter is based on the fast buildup of edge instabilities. A technical solution is suggested, and the performance of the interrupter when used in the second stage of peaking the current of helical explosive magnetic generators (HEMGs) and capacitor banks is predicted. It is shown by computer simulation that the interrupter can operate in the submicrosecond range and switch currents as high as several tens of megaamperes, the operating speed of the interrupter increasing with linear current density. The limit actuation time of the interrupter may be on the order of 100 ns. A prototype of the interrupter is experimentally verified on a capacitor setup by switching currents with an amplitude of 4.3–4.5 MA.

We describe an off-line nanosecond charging device for a short forming line; the device has been created on the basis of an inductive energy storage unit. Energy storage is carried out by the current of an explosive magnetic cumulation generator, and the energy output to the load, by means of an electroexplosive current interrupter. The use of a two-stage, instead of a one-stage, magnetic cumulation generator, consisting of a preamplifier and a dynamic transformer, and two smaller-size generators with sequential connection of secondary windings of dynamic transformers, one of which is connected to the inductive storage unit, and the other, to the current interrupter—has made it possible to substantially increase the line charge voltage. As a result, within a time on the order of 100 ns, it was possible to charge a forming line with an electric length of 5 ns to a voltage of ≥1 MV.

Field electron emission current measurements during the recovery phase of vacuum interrupters are carried out to understand the origin of restrikes in case of interrupting capacitive loads. A special shunt is designed for this measurement. To compensate the capacitive current component due to the stray capacitance of the interrupter, hardware (electronic, on-line) as well as software (off-line) processing are developed for different applications. Measurement and analysis of field emission currents (0.01-5 mA) from current zero until the moment of restrike are performed both in an experimental circuit as well as in full-power test-circuits with commercially available vacuum circuit breakers (up to 36 kV rated voltage). In this context, the influence of capacitive breaking currents on the dielectric recovery of the vacuum gap and the contacts surface condition is studied. Furthermore, the influence of pre-arcing at contact closing under inrush currents in the range of several kilo-amperes and kilo-hertz on the field emission characteristics after capacitive current switching is investigated. The number of making operations as well as the amplitude of the inrush current is varied. A clear relation between inrush current during closing and field emission current after interruption was established.

The breaking ability of a vacuum arc interrupter with a uniform transverse magnetic field formed by a system of permanent magnets was investigated experimentally. The vacuum interrupter with a 0.5-μF shunting capacitor switched off a dc current of up to 150 A at magnetic fields of 100–180 mT. At magnetic fields of 120–160 mT, the breaking ability of the vacuum interrupter was increased to 300 A by introducing a nonuniformity in the magnetic field distribution near the contact surface.

A description is given of the structure of a vacuum interrupter for 110 kV with two breaks per pole. The results of preliminary tests are given.

In this study, we predicted the thermal breakdown of high-voltage interrupter with the characteristics of thermal plasmas such as temperature, pressure and concentration of the ablated material by using a commercial CFD program. The results showed that the pressure build-up inside the chamber was proportional to the magnitude of applied current because the quantities of heat energy and ablated mass also increase together with the current during the compression process. During the decompression process, the reverse flow found did not coincide with the magnitude of current due to the compressibility of the gas through backflow channel. The present method is expected to be useful for the design of guideline and interruption capacity on the thermal breakdown of a PASB chamber.

In recent years, a number of disruptive dielectric failures of unknown cause have occurred on grading capacitors installed on circuit-breakers switching shunt reactors. In an attempt to clarify the origin of these failures, the electrical stresses to which the grading capacitors are subjected in service have been studied. Following initial studies, attention was focused on the first parallel circuit, i.e., the circuit consisting of the grading capacitor and the associated interrupter. It is proposed that the observed failures can be explained by unequal voltage sharing under switching operations, where one interrupter of a pole prestrikes or reignites momentarily before the other interrupter(s) of the same pole. Simulations show that under worst-case conditions, the voltage across one grading capacitor of a pair may then approach a value of 1.5 times the source voltage in the case of a prestrike and three times the source voltage in the case of a reignition. These are substantial dielectric stresses as they correspond to three and six times the stationary voltage across the capacitor. Measurements of voltages and currents inside the first parallel circuit would be very helpful in a further investigation of these phenomena. Copyright © 2010 John Wiley & Sons, Ltd.

Introduction: High frequency ventilation allows clinicians to treat patients when conventional ventilation is not sufficient. Various mechanical methods are used to achieve high frequency ventilation and these differences can have clinical significance. For example, the difference between passive and active exhalation is very significant when comparing the High Frequency Oscillatory Ventilator (HFOV) with the High Frequency Jet Ventilator (HFJV). The HFOV diaphragm creates an oscillatory pressure wave with both positive and negative pressures and gas flows (active ventilation). HFJV uses a flow interrupter to create high frequency pulse “breaths” without generating any negative pressure …

This paper presents the results of current zero measurements during short-line fault interruption tests performed on three variants of an SF6 circuit breaker (CB) (245 kV, 40 kA) with a new mechanism for increasing the contact motion speed, shortly named double-speed mechanism, in order to distinguish between double-motion systems where both contacts are moving. The application of a double-speed mechanism provides the necessary increase of contact separation speed, without a significant increase of opening energy. Besides that, it does not requires any fixed mechanical connection between the stationary and moving contacts through the nozzle. This feature has a positive impact on the CB reliability and creates the possibility of easier assembly and dismantling of the interrupter from its insulator. High-resolution measurements of near current-zero arc current and voltage were carried out during these tests. Different levels of information on the “quality of interruption,” obtained from current zero measurements are presented. Direct observation of arc current and arc voltage data are analyzed. The arc conductivity very shortly (500 and 200 ns) before current zero, as an indicator of the performance of the breaker under test is discussed. All information obtained during current zero measurement is in correlation with the direct results of testing and with design improvements in successive variants of the CB.

An asymmetrical structure GCB that employed the closing resistor method has an interrupter and a closing resistor contact in one shield, and so the shield diameter becomes large. In this study, we investigated the optimum tank diameter and major radius of shield electrode of asymmetrical structure GCB by three-dimensional electric field calculation. We also investigated these optimum structures of symmetrical structure GCB and compared the result with that of the asymmetrical structure GCB. We found that the tank diameter of asymmetrical structure GCB becomes larger than the tank diameter of symmetrical structure GCB by 24%. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(2): 14–20, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20741

Interrupter resistance (R(int)) is a useful measure of airway caliber in young children, but has not been well characterized in infants-in whom there are concerns about the accurate measurement of driving pressure. This study aimed to assess the feasibility and repeatability of measuring R(int) in unsedated newborn infants, and to explore alternative algorithms for calculating driving pressure. R(int) measurement was attempted in 28 healthy term newborn infants during natural sleep using the MicroRint device. Paired R(int) measurements were achieved in 24 infants, but after screening of waveforms only 15 infants had at least 5 technically acceptable waveforms on both measurements. R(int) values obtained were comparable with reported values for airflow resistance in newborns using other methods. However, the repeatability coefficient (CR) was much higher than reported values in preschool children using standard back-extrapolation algorithms, with CR 2.47 KPa L(-1) sec (unscreened) and 2.93 KPa L(-1) sec (screened). Other algorithms gave only marginally better repeatability, with all CR values over 50% of the mean R(int) value. Using current commercially available equipment, R(int) is too poorly repeatable to be a reliable measurement of airflow resistance in newborn infants. Lower deadspace equipment is needed, but anatomical and physiological factors in the infant are also important.

The structure, hardness, strength and plasticity of a microlayer Cu–Cr composite for interrupter contacts in vacuum circuit breakers, which is obtained by electron beam physical vapour deposition, were studied over a temperature range of 290–1070 K. Correlation between the hardness and strength of the composite was established.

This paper is the first in a series devoted to the metrological evaluation of the interrupter technique (IT). The aim of it is to propose effective modification of the classical algorithm and to summarize the research concentrated on evaluating the usefulness of the pressure and flow data frequency analysis on the estimation of the mechanical status of lungs. Based on the Frey et al. reports, a physical–mathematical representation of the respiratory system (modified DuBois’ model) was used. The electrical analog expresses the division of the physiological object into the tissue and airways segments. For such a theoretical structure, the optimal configuration of the measurement signals and the tools of their analysis have been simulated by means of forward–inverse modelling. At this stage, the possibility of expanding the inference on the system mechanics was shown. At the same time, the improvement of repeatability and evaluation precision in relation to the known IT realisation was observed.

The plethysmogram is measured at different points of human body by using the photo interrupter, which sensitively depends on the physical and mental situation of human body. In this paper the statistical method of the data-analysis is investigated to discuss the dependence of plethysmogram on stress and aging. The first one is the representation method based on the return map, which provides usuful information for the waveform, the flucuation in phase and the fluctuation in amplitude. The return map method makes it possible to understand the fluctuation of plethymogram in amplitude and in phase more clearly and globally than in the conventional power spectrum method. The second is the Lisajous plot and the correlation function to analyze the phase difference between the plethysmograms of the right finger tip and of the left finger tip. The third is the R-index, from which we can estimate “the age of the blood flow”. The R-index is defined by the global character of plethysmogram, which is different from the usual APG-index. The stress- and age-dependence of plethysmogram is discussed by using these methods.

塗膜の劣化評価は，主に外観観察により目視評価することが一般的に実施されているが，目視により塗膜の内部や塗膜下の腐食を評価することは不可能である．そこで，非破壊的手法による定量的塗膜評価方法として走査型超音波顕微鏡，カレントインタラプタ法に着目した塗膜評価方法の検討を行った．その結果，走査型超音波顕微鏡は目視では確認できない塗膜層間ふくれを定量的に観察することができたが，カレントインタラプタ法では観察することができなかった．今回の実験からは，走査型超音波顕微鏡観察とカレントインタラプタ法測定の相関関係を得ることはできなかった．

BACKGROUND: The interrupter technique is increasingly used in preschool children to assess airway resistance (Rint). Use of a bacterial filter is essential for prevention of cross-infection in a clinical setting. It is not known how large an effect this extra resistance and compliance exert upon interrupter measurements, especially on obstructive airways and in smaller children. We aim to determine the contribution of the filter to Rint, in a sample of children attending lung function testing at an asthma clinic. METHODS: Interrupter measurements were performed according to ATS/ERS guidelines during quiet normal breathing at an expiratory flow trigger of 200 ml s(-1), with the child seated upright with cheeks supported and wearing a nose clip. A minimum of 10 interrupter measurements was made with and without a bacterial filter. Spirometric and plethysmographic tests were also performed. RESULTS: A small but significant difference (0.12 (95% CI 0.06-0.17) kPa s L(-1), P = 0.0002) with 2x SD of 0.34 kPa s L(-1) was observed between Rint with and without filter in 39 children, with a large spread. This difference was not dependent on Rint magnitude, age or height, nor on lung function parameters (effective resistance, forced expiratory volume in 1 sec, and maximal expiratory flow at 50% of expired vital capacity). CONCLUSIONS: A bacterial filter causes a small difference but is not clinically significant, with a wide spread comparable to the variability of the technique and recommended cut-offs for assessing repeatability and bronchodilation. Age, height or severity of obstruction need not be corrected for in general.

In this paper, we propose the UbiFloorII, a novel floor-based user identification system to recognize humans based on their stepping pattern, the arrays of the transitional footprints from heel-strike to toe-off. To obtain users' stepping pattern from their gait, we deployed photo interrupter sensors instead of switch sensors used in the UbiFloorI. We developed a software module to extract stepping pattern from users' gait. For user identification, we employed neural network trained with users' stepping samples. We achieved about 92% recognition accuracy using this floor-based approach. The UbiFloorII system may be used to automatically and transparently identify users in a home environment.

This paper introduces research work on the development of high-voltage (HV) vacuum circuit breakers (VCBs) in China from its starting point in 1989 to 2006. In this period, a 126-kV two-breaks VCB prototype and a 126-kV single-break VCB prototype were developed. A latest 252-kV single-break interrupter prototype is introduced. Five HV VCBs technologies are discussed, which include HV vacuum insulation, high current interrupting technology with long contact gaps, increasing nominal current, operating mechanism characteristics, and contact bouncing damping. In vacuum insulation, adding a metal ring at the electrode back can decrease breakdown possibilities in the gap between the electrode back and the main shield. A surface melting layer of contact material could have an influence on voltage withstanding capability of a vacuum gap. For interrupting high current with long contact gaps, a strong axial magnetic field (AMF) is needed for better vacuum arc control. Therefore, a single coil AMF electrode is introduced. Heat radiators are effective to increase the nominal current of VCBs. Thermal analysis can help to give appropriate design parameters. There is an optimum opening characteristic that is helpful to improve the interrupting performance of VCBs. Permanent magnet operating mechanism and spring-type operating mechanism are suitable for HV VCBs. Contact bouncing in HV VCBs can be damped by installing contact spring and bellows on the stationary end of VCBs.

In order to examine the ultimate high-voltage interruption ability of a vacuum interrupter, a particle in cell-Monte Carlo collision computer simulation was conducted under the following conditions. Residual charged and neutral particles at current zero were arranged between the electrodes. The particle conditions were obtained from an extrapolated value of experimental data. Secondary electron emission and self-sputtering effects due to ion bombardment were also considered for the simulation. The simulation voltage, which also represents the recovery voltage, was applied between the electrodes. From the results of a simulation on a 168-kV/25-kA 40-mm-diameter one-break interrupter, it was found that the breaking ability is most influenced by the initial neutral particle density. The charged particle density and the secondary electron emission coefficient were found to have a lesser effect on the breaking capability. Consequently, it is estimated that the self-sputtering coefficient from ion bombardment is one of the most important parameters for metal vapor supply after current zero.

In this paper the vacuum arc behaviors of the axial magnetic field (AMF) electrode with single coil structure were investigated at gap distance 10 mm and 40 mm respectively. And the axial magnetic field distribution was computed at 10 mm and 40 mm. A high-speed charge couple device (CCD) video camera was used as a major diagnostics to investigate the arc behaviors. At gap distance 10 mm, the vacuum arc maintained diffuse. With the gap distance increasing from 10 mm to 40 mm, the vacuum arc experienced constricted arc modes only in short time at beginning. In most of time, the vacuum arc kept diffuse. The test results proved that the AMF electrode with single coil structure was feasible to be applied in high voltage vacuum interrupter.

An asymmetrical structure GCB that employed resister closing method equips an interrupter and a closing resister contact in one shield, and so the shield diameter becomes large. In this study, we investigated the optimum tank diameter and major radius of shield electrode of asymmetrical structure GCB by three-dimensional electric field calculation. We also investigated these optimum structures of symmetrical structure GCB and compared the result with that of the asymmetrical structure GCB. In conclusion, the tank diameter of asymmetrical structure GCB becomes larger than the tank diameter of symmetrical structure GCB by 24%.

To understand physical phenomena in gas circuit breaker, we developed a highly accurate analysis method for compressible fluid considering arc behavior. The feature of the method is as follows, (1) To suppress numerical oscillation, the product of density and internal energy is treated as unknown valuable of transport energy equation solved by CIP (Constrain of Interpolation Profile) method. (2) To consider the effect of ablation of nozzle wall the rate of evaporation is assumed to be proportion to the difference between the power emission rate of wall and the intensity of radiation in the space. (3) To solve linear equation systems appeared in pressure, electric and radiation fields, we have improved PCG (Preconditioned Conjugate Gradient) method by reduction of unknowns. We have applied the method to an ablation measurement test stand and an interrupter model of gas circuit breaker, and confirmed the calculation results agree with the experimental ones.

High power testing methods for HV DC circuit breaker (DCCB) were investigated. Short circuit breaking tests using quasi-DC current were performed for DCCB based on the current oscillation scheme with active current injection. This DCCB has a high voltage vacuum circuit breaker as the interrupter unit. The tests were performed using two kinds of testing method (power frequency current peak method and charged reactor method) which have different breaking current waveforms. Interruption performance evaluated with the results obtained from each of the two kinds of testing method. In results, the interruption performance evaluated from these two testing method was same. Moreover, the effect of saturable reactors to the prototype DCCB was investigated in order to improve the DC current interruption performance. Due to the effect of the saturable reactors, di/dt at current zero could be decreased which makes it possible to minimize the parallel capacitance and inductance.

In this paper, the impact of several 145 kV 40 kA GIS (Gas Insulated Switchgear) circuit breaker design parameters, such as length of the main nozzle throat, contact travel and average opening speed, on the estimated breakdown voltage of the contact gap of an interrupter during capacitive current breaking is analyzed. A new approach for breakdown voltage estimation, which provides full correlation between all circuit breaker design parameters and dielectric characteristics of the contact gap and the criterion for breakdown occurrence, was used for this purpose. The estimated capacitive current breaking capability of the circuit breaker was verified by type testing in KEMA High Power Laboratory, the Netherlands.

With the development of more-electric and all-electric aircraft technology, it is a trend to unify secondary energy sources, such as mechanical energy, pressure energy, hydraulic energy and so on, into electric energy gradually. Obviously the capacity of power system, distribution system and consumer equipment will experience a giant promotion. The variable-frequency power system has become the most important development orientation for the future aircraft. It is the most advanced technology around the world that intermediate-frequency (360Hz∼800Hz) electric power is supplied by the variable-frequency generator which is connected to the engine directly. In this paper, intermediate-frequency (400Hz) vacuum arc in the cup-type interrupter with axial magnetic field (AMF) is generated by the oscillating circuit. In the condition of 3mm opening gap, experiments of different current are carried out in interrupters with the diameters being 41mm and 58mm, and the electrode materials being Cu, Cu-W-WC alloy and CuCr50 alloy respectively. The arc voltage and the transformation of arc performance are analyzed contrastively. It is indicated by the experiment results that breaking capacity of vacuum interrupter and properties of intermediate-frequency vacuum arc are closely related to the electrode diameter and material. With the electrode diameter increasing, arc voltage decreases gradually, and diffuse arc tends to be stable, for which the breaking capacity is better. For the same size of electrode diameter, the breaking capacity in CuCr50 is better than that both in Cu and Cu-W-WC.

In this paper, numerical methods to detect series arc fault in lithium-ion batteries are presented. The arc signals which are required for detecting arc fault are obtained using a test bench on which the Current Interrupt Device (CID) opens dynamically by contact release, associated with a 48 V DC battery pack and a resistor which can deliver a maximum of 1000 A. A comparison between the signals with and without arc is done to detect differences that can be used for arc detection. To isolate the arc signature, several methods are used, among them: the spectral analysis of arc signals using a Fast Fourier Transform (FFT) algorithm and a periodogram, the linear regression (moving average), the arc signals derivative and the filtering techniques. The spectral analysis shows a rise of the signal amplitude at high frequencies while the derivative method and the linear regression, among other things, show the instant when the arcing event occurs. Detection criteria may be set according to the type of method implemented. All of these methods mentioned above can be used to develop an Arc-Fault Circuit Interrupter (AFCI) for lithium-ion batteries.

In a SF6 self-blast interrupter with the magnetic-field-producing coil, electrical arcs make hot gas flows driven into the expansion chamber for generating the blowing-off force during the high-current phase. When the fault current approaches natural current zero, this force can be used for cooling down and quenching the residual arcs. And the interaction of electrical arc-gas flow is critical to predict the phenomena happened after current zero such as thermal recovery process. In this study, we calculated SF6 arc plasmas caused by fault current interruption inside a self-blast interrupter using a computational fluid dynamics technique and investigated the thermal recovery process according to the magnetic-field-producing coil with the concept of post-arc current.

The ground fault is one of the most common faults in the Photovoltaic (PV) power generation system. Previously, the ground fault detection interrupter (GFDI) and spread spectrum time domain reflectometry (SSTDR) methods were applied in the PV system to detect the ground fault of PV arrays. However, the limitations of GFDI constrain its ability to detect high impedance ground fault (HIGF) at PV arrays, and the implementation of SSTDR will increase the system cost. A novel approach based on the common mode (CM) model of the full-bridge inverter to detect the HIGF of PV arrays is proposed in this paper. Both the mathematical verification and PSIM simulation prove the effectiveness of CM model in detecting the HIGF for transformerless single-phase PV systems.

In SF6 puffer-assisted self-blast interrupters, which are being developed as the next-generation switching mechanism, the arc burns within insulating nozzles with an ablation of the nozzle material and leads to an incoming gas flow for the pressure chamber with a pressure-rise during the high-current phase. Close to current zero, the arc can be cooled down and quenched completely by the reverse gas flow from the chamber to the arcing zone according to the pressure gradient between them. Therefore, the interruption of fault currents is dependent on the thermal decay of arcs during the current-zero phase by the blowing-off force, which is generated by the pressure-rise of the chamber during the high-current phase. In this study, we calculated SF6 switching arcs caused by fault current interruption inside a SF6 puffer-assisted self-blast interrupter with the reversed stroke of electrode and investigated the thermal breakdown with thermal decay near current zero.

During the closing operation of a capacitive load by a vacuum interrupter, there is always a prestrike arc. An inrush current with high frequency and high amplitude flows through the prestrike arc. This prestrike arc with a high energy density destroys contact surfaces locally, resulting in welding between the mated contacts. Consequently, the opened destroyed surfaces, which enhance the local electric fields and bring metal particles into the contact gap, increase the restrike probability of the interrupter under a DC recovery voltage. The objective of this paper is to establish a kinetic model to investigate the characteristics of prestrike arcs and the energy fluxes to the electrodes during closing capacitive loads. The Particle in Cell-Monte Carlo Collision(PIC-MCC) method was adopted in this model to describe this high density plasma within a small gap. The distance between the contacts was set to 1μm. Three different electrode temperatures were set to investigate their influence on results. Electron-atom elastic collision and electron impact ionization were considered in the model. According to the results, the plasma density, current density and energy fluxes to electrodes increased with electrode temperature. The length of arc column also increased with electrode temperature. Electron current was main component of the current. Electron energy flux was less than ion energy flux at cathode, while it was just the reverse at anode.

Side channel blowers are used in a wide range of applications like the paper and printing industry, dental vacuum, industrial vacuum cleaners or road sweepers. As all these applications occur in the neighborhood of human beings, a low noise emission of the side channel blowers is necessary. To obtain an closer insight to the flow field and the noise produced, this paper is dealing with pressure measurements in the rotating impeller of a double flow side channel blower. Seven thin line pressure sensors are integrated into two opposing blade surfaces to measure the pressure distribution within one blade segment. The necessary modifications to the impeller as well as the housing and the mounting of the telemetric system are demonstrated. A pressure correction will be applied to correct the pressure offset due to the used measurement technique. The results show the exemplary time trend of the pressure, the phase averaged pressure generation for different working points and rotational speeds of 50Hz and 60Hz. Especially, the pressure distribution during the passage of the interrupter region is analyzed. Additionally, the results are presented in the frequency domain. The pressure measurements are linked to the acoustic noise emission by the application of an acoustic analogy and its source definition by the second time derivative of the measured, hydrodynamic pressure.

This paper is connected with investigation of cold rate of rise of electric strength of 525 kV SF 6 live tank circuit breaker. The article describes controlled opening during opening operation of puffer SF 6 Circuit Breaker. The method gives the real estimation of gas flow influence to dynamic breakdown characteristic of puffer interrupter. The purpose of this article is to give the correlation between breakdown voltage characteristic and opening speed of circuit breaker as well from changing of filling pressure value.