Characteristics Of Breaker Research Articles

Modeling of the Dynamic Characteristics of Spring-Operated Gas Circuit Breakers

Modeling of the Dynamic Characteristics of Spring-Operated Gas Circuit Breakers

Comparison of numerical models in radiative heat transfer with application to circuit-breaker simulations

Two different modeling approaches for the numerical computation of the radiation energy exchange in the context of the simulation of high-voltage circuit breakers are investigated. These are the basic Radiative Transfer Equation method and the P1 model which are compared with respect to the modeling methodology and their predictive capabilities. For each of these two models, two distinct implementations, the present code and the commercial package Fluent, are compared to a classical analytical solution. A more demanding evaluation using a configuration exhibiting typical complex circuit breaker characteristics is presented with a critical assessment.

A Novel Smart High-Voltage Circuit Breaker for Smart Grid Applications

In this paper, we propose a new “intelligent operation” concept for high-voltage SF6 gas circuit breakers, in which the moving contacts are self-adaptively controlled from one position to an adjacent position to improve the circuit breaker life cycles. To analyze the concept intelligent operation, a new model of high-voltage SF6 gas circuit breaker is developed, and the moving characteristics of the new type circuit breaker are computed based on the newly designed model. Then both mechanical and electrical wears are quantitatively analyzed according to the breaker's new moving characteristic. Finally, we demonstrate the life cycle improvement of the new type of high-voltage SF6 gas circuit breaker. Our analysis can also be used to estimate the remaining life cycle of a breaker based on the tallied data collected by our intelligent modules.

Dielectric characteristics of vacuum circuit breakers with CuCr and CuBi contacts before and after short-circuit breaking operations

This paper presents the results of the degree of irreversible changes of dielectric properties of vacuum circuit breakers with CuCr and CuBi contacts before and after short-circuit breaking operations. Tests of dielectric properties were performed on four different types of switching vacuum chamber with RMF electrodes in the form of a spiral disk with slots. The paper describes the configuration of measuring system for determining the dielectric properties of circuit breakers with DC, AC and pulse voltage. It also describes the measuring procedure. The results were analyzed and the experimentally obtained random variable breakdown voltage is found to belong to Weibull distribution in all cases. Based on these results it was found that for the vacuum circuit breakers with CuCr contacts and CuBi breakdown occurs by the emission mechanism after stopping of diffuse arc with the initial breakdown at the anode. It was also found that significant reduction of the breakdown voltage occurs only after a short-circuit current breaking for a constricted arc. Only in this case, the significant difference between circuit breakers with CuBi and CuCr contacts is observed. This difference is explained by the fact that breakdown voltage for a constricted arc strongly depends on the shape of the applied voltage by the action mechanism of micro particles generated during the breaking of the arc current for the vacuum circuit breakers with CuBi contacts and it is caused by material of contacts. The results confirm the lower degree of irreversible changes of dielectric properties of vacuum circuit breakers with CuCr contacts in operation.

Experience in using recorders of synchronized current and voltage measurements on 110 kV overhead power lines

The results of an investigation of the functioning of recorders of synchronized measurements of electromagnetic transients on the Pugachi – Akbulak 110 kV overhead transmission lines (a branch of the JSC “IDGC of Volga” — “Orenburgenergo”) when checking the technical characteristics of oil-filled circuit breakers and when determining the location of a fault on the line by the wave method of bilateral measurements are presented.

Transformer Failure Due to Circuit-Breaker-Induced Switching Transients

Switching transients associated with circuit breakers have been observed for many years. Recently, this phenomenon has been attributed to a significant number of transformer failures involving primary circuit-breaker switching. These transformer failures had common contributing factors such as the following: 1) primary vacuum or SF-6 breaker; 2) short cable or bus connection to transformer; and 3) application involving dry-type or cast-coil transformers and some liquid-filled ones. This paper will review these recent transformer failures due to primary circuit-breaker switching transients to show the severity of damage caused by the voltage surge and discuss the common contributing factors. Next, switching transient simulations in the electromagnetic transients program will give case studies which illustrate how breaker characteristics of current chopping and restrike combine with critical circuit characteristics to cause transformer failure. Design and installation considerations will be addressed, particularly the challenges of retrofitting a snubber to an existing facility with limited space. Finally, several techniques and equipment that have proven to successfully mitigate the breaker switching transients will be presented, including surge arresters, surge capacitors, snubbers, and these in combination.

Study of commutation characteristics of fast controlled vacuum circuit breaker in single phasing

An original scheme for a fast-acting vacuum switch based on the hybrid control of a vacuum discharger with vacuum switches is proposed and substantiated. We developed and prepared an experimental model of for single-pole switching and present results of a study of its commutation characteristics.

Effects of Various Factors on Gas Blast Characteristics of Auto-Expansion Type Gas Circuit Breaker

Auto-expansion type gas circuit breaker has a feature that operating energy can be reduced. However, the optimum design is very difficult, because this type of breaker has the gas chambers, one of which generates high gas pressure by using the heat of the arc and the other chamber generates high pressure by mechanical compression. Therefore, before designing this type of breaker, it is desirable to know what factors influence the gas blast characteristics. In this paper, we describe the influences of various factors on the gas blast characteristics using our own pressure calculation program.

IEC 60364 기반 접지계통 비교 분석

본 논문에서는 IEC 60364에서 제시하고 있는 접지계통(TT접지계통, TN-S 접지계통 및 TN-C)의 누전차단기 동작특성 및 보호도체의 임피던스변화에 따른 Loop Impedance 특성분석을 실시하였다.<BR> 분석결과 Loop Impedance의 경우 저항성분과 인턱턴스성분에 영향을 받는 것으로 나타났다. 접지계통별 전류?전압특성은 TN-S 접지계통 및 TN-C 접지계통의 경우 사고전류가 높고 접촉전압이 낮은 특성을 나타낸 반면 TT 접지계통의 경우 사고전류는 낮고 접촉전압이 높게 나타남을 확인하였다.

Relationship Between the Voltage Distribution Ratio and the Post Arc Current in Double-Break Vacuum Circuit Breakers

In many cases, single-break vacuum circuit breakers are used as circuit breakers, and so the characteristics of double-break vacuum circuit breakers have not received sufficient attention. This report describes our investigations of the interruption characteristics of double-break vacuum circuit breakers. We have investigated and clarified the relationship between the voltage distribution ratio and the post arc current in double-break vacuum circuit breakers by measuring the post arc current in the single-break vacuum circuit breaker, the voltage distribution ratio, and the post arc current in double-break vacuum circuit breakers. Our investigation has shown that the post arc current scatter of the spiral contact is much larger than that of the axial magnetic field contact. This result shows that the bias of the voltage distribution ratio was caused by the imbalanced post arc current in each vacuum interrupter in the double-break vacuum circuit breaker. Therefore, we conclude that axial magnetic field contacts are suitable for double-break vacuum circuit breakers.

Improvements of protective characteristics of automatic low-voltage circuit breakers

Suggestions on how to improve the protective characteristics of automatic low-voltage breakers, namely, to increase the sensitivity to remote short-circuits (faults), to raise the speed of selective protection, and to enhance the reliability by long-distance (remote) backup are considered. The use of the power function of a current to quickly identify the reason for a circuit disturbance and determine the rms current value of the current’s periodic component is grounded. Advantages of the use of the Joule integral as a criterion to selectively operate breakers are shown.

Impact Research of Inductive FCL on the Rate of Rise of Recovery Voltage With Circuit Breakers

Fault current limiter (FCL) is expected to ease the burden on circuit breakers by limiting the fault current to a desired level. However, the burden on the circuit breakers depends not only on the interrupting current but also on the rate of rise of recovery voltage (RRRV). Based on an equivalent model of the inductive FCL and with respect to FCL terminal fault and short-line fault respectively, strict mathematical formula are presented to describe the relationship between the RRRV and the current limit factor, the stray capacitance as well as the short-line fault distance. Further, detailed computations were carried out regarding a 220-kV transmission line with three-phase-to-ground faults to fully account for the concrete impacts on the RRRV from key influential factors. The calculation results by the proposed theoretical formula in this paper coincide well with the simulations in some previous publications. The specific investigation presents analytical basis and theoretical reference for optimal parameter design of inductive FCLs and reliable selection of the interrupting characteristics of HV circuit breakers.

An Analysis of Let-through I 2 t Variations of a Current-limiting Circuit Breaker by Non-simultaneous Closing in Short-circuit Conditions

The let-through I2 t characteristics of a current-limiting circuit breaker are provided by a manufacturer and generally determined by a desk study during the design stage and then verified by tests. However, under short-circuit conditions, they can be different from that given when the non-simultaneous closing of the current-limiting circuit breaker occurs; this causes an unintentional operation of the upstream protective device to clear the fault. This article presents the influence of non-simultaneous closing on the let-through I2 t variations of the current-limiting circuit breaker in short-circuit conditions by using a simulation study. The simulation results indicate that the let-through I2 t values obtained by the non-simultaneous closing of the current-limiting circuit breaker have significantly more variations than that obtained by simultaneous closing.

Interruption characteristics of double-break vacuum circuit breakers

Since the majority of vacuum circuit breakers in use are of the single-break variety, there have been few studies of double-break vacuum circuit breakers. This report describes our investigations of the interruption characteristics of the double-break vacuum circuit breaker. In this investigation, the post arc current and recovery voltage distribution ratio were measured in order to clarify the relationship between them. The results show that a bias of the voltage distribution ratio occurs when the post arc current value becomes imbalanced. In addition, the measurements of the post arc current for circuit breakers with spiral contacts are very scattered as compared with those with axial magnetic field contacts. Normally, the double-break vacuum circuit breaker consists of two contacts of the same type. However, when two spiral contacts are used, the scattering of post arc current causes a current imbalance. As a result, a bias of the voltage distribution ratio may occur. It appears to be preferable to use double-break vacuum circuit breakers with axial magnetic field contacts.

Analyses of mechanical characteristics of vacuum circuit breaker during the closing process taking electrodynamic force into account

A dynamic model for the closing process of a medium-voltage vacuum circuit breaker (MVVCB) is constructed, and the automatic dynamic analysis of mechanical system software is applied to construct the model by taking electrodynamic force into account. After the electrodynamic force is worked out, the model is employed to investigate the mechanical characteristics during the closing process of a MVVCB under the influence of electrodynamic force. The characteristics are also investigated through experiment. Moreover, the simulation and experimental results are in close agreement. The results show that the electrodynamic force not only reduces the moving speed of the main axle&apos;s angle to a certain degree but also influences the four parameters used to describe the performance of mechanical characteristics. The simulation and experimental results presented here can be used to highlight the design criteria on the optimal operation and condition monitoring of MVVCBs.

Calculation of the interruption Process of a self-blast circuit breaker

Because the physics occurring during an interruption process is not well known, it is not easy to analyze the characteristics of a self-blast circuit breaker neither theoretically nor experimentally. Fortunately, the available computational power and the numerical method improved recently made it possible to predict an interruption process as precisely and fast as possible. Therefore many researches using computational methods have been done for the interruption process of interrupters and applied to extend the information such as thermal and dielectric reignition. In this paper, we have simulated the interruption process of SF/sub 6/ self-blast circuit breakers with the arc plasma during the fault interruption of a 10-kA current. The computational fluid dynamics program used here is coupled with the electromagnetic field analysis, the radiation model, and the effects of turbulence. Through this work, we have obtained further information about the thermal performance as well as the behavior of the arc. The results have been compared with the measured arc voltage.

Theoretical and experimental analyses of the mechanical characteristics of a medium-voltage circuit breaker

A dynamic model for a medium-voltage vacuum circuit breaker is constructed using the ADAMS software. The model is used to investigate the mechanical characteristics of the circuit breaker under the influence of electrodynamic forces. The characteristics are also investigated experimentally. The simulated and experimental results are in close agreement. It is shown that electrodynamic force increases the breaking speed of the moving contacts by 0.2 m/s. The model can be used to highlight design criteria for the optimal operation of medium-voltage circuit breakers.

The Influence of Vacuum Circuit Breakers and Different Motor Models on Switching Overvoltages in Motor Circuits

Switching of induction motors with vacuum circuit breakers continues to be a concern. In this paper the influence on statistical overvoltages of the stochastic characteristics of vacuum circuit breakers, high frequency models of motors and transformers, and network characteristics, including cable lengths and network topology are evaluated and a general view of the overvoltages phenomena is presented. Finally, a real case study on the statistical voltage levels and risk-of-failure resulting from switching of a vacuum circuit breaker in an industrial installation in Hong Kong is presented.

Prospects for Using Nuclear Power Systems in Commercial Ships in Northern Russia

The experience gained over many years of operating nuclear-powered ice breakers in conquering the northern sea route is described. The conditions which must be met for year-round navigation of cargo ships in the Arctic are presented. For such navigation to be realistic, it must be profitable and Russian national interests in the region must be protected in accordance with the Maritime Policy of the Russian Federation for the period up to 2020. Information is also given concerning the technical status of operating nuclear-powered ice breakers and the characteristics of ice breakers and new-generation nuclear power systems.

Boundaries of the plasma-free regime of electroexplosion of a foil

Results of the experimental studies of the commutation characteristics of an electroexplosive breaker upon heating of a copper foil by a current pulse of duration τ≈1msec are given. The dependences of the electric-field strength and the specific power of the circuit breaker during an electroexplosion of the foil on the specific power of the source Ps are found and it is shown that the transition of the plasma-free regime of electroexplosion of the foil to a plasma regime occurs for Ps=30–40GW/g.