High-voltage Gas Circuit Breaker Research Articles

Two-dimensional Axisymmetric Modeling of the Magnetic Field for High-voltage Gas Circuit Breakers

High fidelity numerical analyses of high-voltage gas circuit breakers have been conducted at Hitachi Energy Research with an in-house CFD-based arc simulation tool. The tool extends the capability of a commercial flow solver (ANSYS Fluent) to represent physical phenomena at play in a high voltage circuit breaker during a breaking operation, such as magnetostatics, polymeric and metal evaporation, and arc-network interaction. This work describes the implementation of the Biot-Savart law for computing the magnetic field generated by an electric arc under the magnetostatic approximation and in two--dimensional axisymmetric conditions. The implementation is compared to the reference one based on the magnetic vector potential formulation of the Amp`ere’s law in the Coulomb gauge. The limitations of the two formulations are discussed and their numerical accuracy compared.

Comparison of measurement and numerical calculation on spectral profile of ablation arc plasma around current zero in high-voltage gas circuit breakers

A product-scale interrupter with a rated voltage range of 245 kV to 362 kV and current condition of 20 kA root mean square has been examined to study the arc extinguishing process and the appearance of absorption spectrum by C2 molecules immediately before the current zero. The latter has elucidated the presence of C2 molecules outside the arc core, where the temperature is lower. The temporal behaviour of the C2 absorption spectrum and the emission spectrum of the S+ ion have been measured, which have indicated that polytetrafluoroethylene ablation gas is replaced by SF6 because of gas flow from the thermal puffer chamber to the stagnation point. The computed spectra agree well with the experimentally obtained spectra and show similarities to measured profiles. They show evidence of absorption by C2 molecules in the continuous spectrum and the reproduced band heads of the C2 Swan spectrum.

Investigation of Discharge Propagation in Localized High-Temperature SF6 Gas With Breakdown Voltage Measurement

In high-voltage gas circuit breakers (HVCBs), high-pressure gas is blown between the electrodes to cool the arc. The temperature distribution between the electrodes at the current zero point has a large gas temperature difference. This study aims to experimentally clarify the effect of the cold gas region on the breakdown voltage of gases with large temperature differences. In an experiment, a hot gas generator using arc heat was used to create a gas space with a large temperature difference between electrodes, and the breakdown voltage was evaluated. The breakdown voltage in the gas space with a cold gas region was twice that of the case, where the space between the electrodes was filled with hot gas. It was found that the discharge initiated in the hot gas region was suppressed in the cold gas region and that the breakdown voltage in a gas space with the hot and cold region was influenced by the existence of the cold gas.

Simulations for Current Interruption in High-Voltage Gas Circuit Breakers

Simulations for Current Interruption in High-Voltage Gas Circuit Breakers

Development and Validation of Integrated High Voltage Gas Circuit Breaker Analysis Code

Development and Validation of Integrated High Voltage Gas Circuit Breaker Analysis Code

Investigation on Pressure Build-Up and Blowing Processes by Multipoint Pressure Measurement and Fluid Analysis for Self-Blast-Type High-Voltage Circuit Breaker

In high-voltage gas circuit breakers, processes to blow high-pressure and low-temperature gas into an arc are important for efficient fault current interruption. Self-blast-type gas circuit breakers obtain a high pressure by using arc energy to blow the high-pressure gas into the arc. In order to understand the self-blast phenomenon, we carried out multipoint pressure measurements to investigate the pressure build-up mechanism and blowing processes quantitatively. Because the pressure in the nozzle throat was particularly high around the arc area, the nozzle throat with a narrow cross-sectional area and high-current density works as a pressure source at a high-current condition. Blowing gas from a thermal puffer chamber becomes dominant when interrupting current decreases, and then a switch is made to the blowing process a few milliseconds before current zero. The pressure ratio between the thermal puffer chamber and nozzle throat agreed well with the pressure ratio calculated from the sound speed condition thereafter around current zero. Therefore, we confirmed the formation of sound speed flow in the nozzle throat, and supersonic flow was established in the nozzle diverging section. It was possible to use the pressure distribution and influence of pin position around current zero in the nozzle diverging section to evaluate gas flow by a theoretical calculation, and the pressure measurement found the influence of stagnation flow by pin contact. The influence of pin contact could be evaluated from the comparison of measurement and gas flow analyses, and it was confirmed that the evaluation of gas flow and interrupter design was possible.

Spring-Operating Mechanism for High-Voltage Gas-Circuit Breaker by applying 1D-CAE method

Spring-Operating Mechanism for High-Voltage Gas-Circuit Breaker by applying 1D-CAE method

Optimization of Dual Motion Mechanism with Double Grooved Cams for High-voltage Gas Circuit Breaker

Optimization of Dual Motion Mechanism with Double Grooved Cams for High-voltage Gas Circuit Breaker

Online Assessment of Contact Erosion in High Voltage Gas Circuit Breakers Based on Different Physical Quantities

In this paper, an effort has been made to evaluate the online condition of arc contacts as a vital component of interruption chamber in high-voltage puffer-type SF6 circuit breakers. The relationship between eroded mass caused by short-circuit current interruption and different thermal stress indices, such as transferred electrical charge, current squared, and arc energy, is investigated by performing many experiments with different current amplitudes and arcing times. It is demonstrated that none of the known indices can solely determine mass erosion caused by the current interruption. Therefore, the equations including two of the defined parameters are proposed to evaluate mass erosion. The method using arc energy and transferred electrical charge owns the highest accuracy in evaluating mass loss. However, considering the complexity of arc voltage measurements, a second method using current and arcing time can be also utilized. In addition, the development of erosion during the lifetime of arc contacts is studied. It is shown that arc roots tend to form on new uneroded areas of the contacts during current interruption, resulting in different erosion rates between the first few and subsequent interruptions due to change of morphology of the contacts after the first few switching operations.

Development of a multiperspective optical measuring system for investigating decaying switching arcs at the nozzle exit of circuit breakers.

High-voltage gas circuit breakers, which play an important role in the operation and protection of the power grid, function by drawing an arc between two contacts and then extinguishing it by cooling it using a transonic gas flow. Improving the design of circuit breakers requires an understanding of the physical processes in the interruption of the arc, particularly during the zero crossing of the alternating current (the point in time when the arc can be interrupted). Most diagnostic techniques currently available focus on measurement of current, voltage, and gas pressure at defined locations. However, these integral properties do not give sufficient insight into the arc physics. To understand the current interruption process, spatially resolved information about the density, temperature, and conductivity of the arc and surrounding gas flow is needed. Owing to the three-dimensional, unstable nature of the arc in a circuit breaker, especially near current zero, a spatially resolved, tomographic diagnostic technique is required that is capable of freezing the rapid, transient behavior and that is insensitive to the vibrations and electromagnetic interference inherent in the interruption of short-circuit current arcs. Here a new measurement system, based on background-oriented schlieren (BOS) imaging, is presented and assessed. BOS imaging using four beams consisting of white light sources, a background pattern, imaging optics, and a camera permits measurement of the line-of-sight integrated refractive index. Tomographic reconstruction is used to determine the three-dimensional, spatially resolved index of refraction distribution that in turn is used to calculate the density. The quantitative accuracy of a single beam of the BOS setup is verified by using a calibration lens with a known focal length. The ability of the tomographic reconstruction to detect asymmetric features of the arc and surrounding gas flow is assessed semiquantitatively using a nozzle that generates two gas jets, as described in [Exp. Fluids43, 241 (2007)EXFLDU0723-486410.1007/s00348-007-0331-1]. Experiments using a simple model of a circuit breaker, which provides optical access to an ∼1 kA arc that burns between two contacts and is blown through a nozzle system by synthetic air from a high pressure reservoir, are also described. The density in the decaying arc and surrounding gas flow is reconstructed, and the limitations of the technique, which are related to the temporal and spatial resolution, are addressed.

Investigation on the Influence of Gas Pressure on CO2 Arc Characteristics in High-Voltage Gas Circuit Breakers

CO<sub>2</sub> is identified as a promising alternative gas of SF<sub>6</sub>. The magnetohydrodynamics (MHD) arc model is established for a CO<sub>2</sub> circuit breaker. The influence of gas pressure is studied. The simulations are carried out for 0.5 MPa, 0.7 MPa and 0.9 MPa absolute filling pressure, allowing predictions of pressure and temperature distributions. The arc time constant θ and the power loss coefficient <em>Q</em> is extracted. The thermal interruption capability is estimated to grow with increasing filling pressure.

Application of 1D-CAE Tool to Development for High-Voltage Gas Circuit Breaker

Application of 1D-CAE Tool to Development for High-Voltage Gas Circuit Breaker

Prediction of Insulation Capability for Ground Fault to Consider Asymmetry in SF6 Circuit Breaker

Currently, most high-voltage gas circuit breakers (CBs) include asymmetrical geometries in the shield, the tank, the hot-gas exhaust, and the connection parts for bushings. For this reason, a 3-dimensional (3-D) analysis of the insulation capability is necessary, rather than a 2-D analysis. However, a 3-D analysis has difficulties due to the computational time and complex modeling. This paper presents a 3-D analysis considering the asymmetry in high-voltage gas CBs and a technique to reduce the calculation time. In the proposed technique, the arc plasma requiring the most computational time is first calculated by a 2-D analysis. Then, the results such as pressure, temperature, and velocity are input as a source for the 3-D analysis. This technique is applied to a 145kV self-blast-type CB and the analysis result exhibits good agreement with the experimental result.

Perspectives on Research on High Voltage Gas Circuit Breakers

The research on high voltage circuit breakers using SF6 is addressed. The current state of the art in this field is shortly reviewed and future research directions are discussed. These are mainly the radiative energy transport, the understanding and description of ablation processes at the nozzle and contact surfaces, the influence of such vapors on pressure build up and interruption capability, electric breakdown processes, departures from equilibrium, turbulence and the importance of magnetic fields and 3D modelling.

CFD Analysis of Arc–Flow Interaction in a High-Voltage Gas Circuit Breaker Using an Overset Method

A computational analysis of the gas flow in a gas circuit breaker is presented in this paper. A structured grid with a high-order conservative overset method is used for an accurate flow analysis. In addition, this paper includes the modeling of the arc, radiation, and ablation of the nozzle. The results of the flow analysis are compared with the experimental data, showing good agreement with the experimental data.

High-speed Spring Operated Mechanism for High-voltage Large-capacity Gas Circuit Breakers

High-speed Spring Operated Mechanism for High-voltage Large-capacity Gas Circuit Breakers

크리깅 메타모델과 유전자 알고리즘을 이용한 초고압 가스차단기의 형상 최적 설계

We describe a new method for selecting design variables for shape optimization of high-voltage gas circuit breaker using a Kriging meta-model and a genetic algorithm. Firstly we sample balance design variables using the Latin Hypercube Sampling. Secondly, we build meta-model using the Kriging. Thirdly, we search the optimal design variables using a genetic algorithm. To obtain the more exact design variable, we adopt the boundary shifting method. With the proposed optimization frame, we can get the improved interruption design and reduce the design time by 80%. We applied the proposed method to the optimization of multivariate optimization problems as well as shape optimization of a high - voltage gas circuit breaker.

Focused Shadowgraphy in the Heating Volume of a High-Voltage Gas Circuit Breaker

The gas or plasma flow in the heating volume is central for the interruption performance of a circuit breaker (CB). This flow is visualized in a real breaker for the first time. Transparent parts were added to the breaker to use the focused shadowgraphy technique. Several experiments show the flow and distribution of the hot gas in the heating volume. The results can be used for further analysis of the gas/plasma flow in a CB.

Arc-induced turbulent mixing in an SF6 circuit breaker model

Dielectric interruption performance of SF6 high-voltage gas circuit breakers depends on the temperature distribution of the gas during the post-arc phase. Understanding the details of the mixing process occurring inside the breaker during arcing is therefore fundamental for the design. Multiphysics simulations are nowadays used to predict the flow field and the energy distribution inside the interrupter during and after the arcing phase. In this paper we make use of an optical technique to observe the arc-induced SF6 mixing process inside a dedicated test device. We extract qualitative and quantitative information and we compare this with simulations to conclude on the suitability of the models used.

Optimal Design of the Electro-Magnetic Actuator for High Voltage Circuit Breaker

The motor-spring and hydraulic actuators have long constituted as a mechanism for HGCB, regardless of the fatal disadvantages of the malfunction. Although many attempts have been made to cope with them, there is no alternative to replace this mechanism. This paper presents a new type of the electric actuator, electro-magnetic force driving actuator (EMFA) for high-voltage gas circuit breaker (HGCB) and describes the principle of the optimal design. Auto-Tuning Niching Genetic Algorithm combined with deterministic method (Pattern Search Method) is developed to reduce the number of object function calls and used for the optimal design. Fabrication and experiment were performed in order to prove the applicability for HGCB overall class. In comparing the experiment with simulated data, it is confirmed that analysis of the dynamic characteristics of EMFA is appropriate for design.