scholarly journals Self-Consistent Modeling of Electrode Motion in a Model Circuit Breaker

2019 ◽  
Vol 6 (1) ◽  
pp. 99-102
Author(s):  
R. Fuchs
Keyword(s):  
Gas Flow ◽  
Low Voltage ◽  
Circuit Breaker ◽  
Computational Grid ◽  
Electrical Circuit ◽  
Gas Pressure ◽  
Circuit Breakers ◽  
Self Consistent ◽  
Coupled Solution ◽  
Model Circuit

<span lang="EN-US">Numerical simulations of low-voltage circuit breakers require a coupled solution of gas flow, electromagnetism, electrical circuit, and other aspects. Including electrode motion is challenging because the computational grid is deformed and data is to be exchanged among dedicated solvers. A central issue is to keep them synchronized. This is addressed with a single framework that allows for a continuously morphing grid and accounting for the cumulative effects of mechanics, Lorentz force, and gas pressure. It is shown that gas pressure has negligible effect.</span>

Gas pressure, Volume and Flow Measurement

2011 ◽  
Author(s):  
Patrick Magee ◽  
Mark Tooley
Keyword(s):  
Airway Pressure ◽  
Gas Flow ◽  
Intrathoracic Pressure ◽  
Wheatstone Bridge ◽  
External Pressure ◽  
Electrical Circuit ◽  
Gas Pressure ◽  
Positive Pressure ◽  
Electrical Analogy ◽  
Metal Bellows

The physics of pressure, flow and the gas laws have been discussed in Chapter 7 in relation to the behaviour of gas and vapour. This section will focus on the physical principles of the measurement of gas pressure, volume and flow. Unlike a liquid, a gas is compressible and the relationship between pressure, volume and flow depends on the resistance to gas flow (or impedance if there is a frequency dependence between pressure and flow in alternating flow, see Chapter 4 for the electrical analogy of this) in conduits (bronchi, anaesthetic tubing); it also depends on the compliance of structures being filled and emptied (alveoli, reservoir bags, tubing or bellows). Normal breathing occurs by muscular expansion of the thorax, thus lowering the intrathoracic pressure, allowing air or anaesthetic gas to flow towards the alveoli down a pressure gradient from atmospheric pressure. When positive pressure ventilation occurs, gas is ‘pushed’ under pressure into the alveoli. Depending on the exact relationship between the ventilator and the lungs, different relationships exist between airway pressure (rather than alveolar pressure, which cannot easily be measured) and gas flow and volume. Gas pressure measurement devices were traditionally in the form of an aneroid barometer, a hollow metal bellows calibrated for pressure and temperature, which contracts when the external pressure on it increases, and expands when it decreases. The movement is linked to a pointer and indicator dial. It is often more convenient to make the device in the shape of part of a circular section, but the principle is the same. This is what the Bourdon gauge, which commonly measures pressure in gas cylinders, looks like. The detection of movement of the diaphragm of an aneroid barometer can take several forms. The movement can either be linked via a direct mechanical linkage to a pointer, or diaphragm movement can be linked to a capacitative or inductive element in an electrical circuit, such as a Wheatstone bridge. Airway pressure during spontaneous breathing or artificial ventilation is low. The preferred units of measurement are cm H2O and the range of values is between −20 and +20 cmH2O. The aneroid barometer to measure this will therefore be of light construction, using thin copper for the bellows material.

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

2017 ◽  
Vol 4 (1) ◽  
pp. 95-98
Author(s):  
Z. Guo ◽  
X. Li ◽  
Y. Zhang ◽  
X. Guo ◽  
J. Xiong
Keyword(s):  
High Voltage ◽  
Power Loss ◽  
Circuit Breaker ◽  
Filling Pressure ◽  
Gas Pressure ◽  
Circuit Breakers ◽  
Promising Alternative ◽  
Arc Model ◽  
Arc Characteristics ◽  
Temperature Distributions

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.

scholarly journals Experimental Investigation of the Prestrike Characteristics of a Double-Break Vacuum Circuit Breaker under DC Voltages

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3217
Author(s):  
Yun Geng ◽  
Xiaofei Yao ◽  
Jinlong Dong ◽  
Xue Liu ◽  
Yingsan Geng ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Direct Current ◽  
Experimental Work ◽  
Low Voltage ◽  
Circuit Breaker ◽  
Circuit Breakers ◽  
Vacuum Circuit Breaker ◽  
In Series ◽  
The Difference ◽  
Single Break

The prestrike phenomenon in vacuum circuit breakers (VCBs) is interesting but complicated. Previous studies mainly focus on the prestrike phenomenon in single-break VCBs. However, experimental work on prestrike characteristics of double-break VCBs cannot be found in literature. This paper aims to experimentally determine the probabilistic characteristics of prestrike gaps in a double-break VCB consisting of two commercial vacuum interrupters (VIs) in series under direct current (DC) voltages. As a benchmark, single-break prestrike gaps were measured by short-circuiting one of the VIs in a double break. The experimental results show that the 50% prestrike gap d50 of each VI in a double break, which is calculated with the complementary Weibull distribution, was significantly reduced by 25% to 72.7% compared with that in a single break. Due to the voltage-sharing effect in the double-break VCB, scatters in prestrike gaps of each VI in a double break was smaller than that in a single break. However, without the sharing-voltage effect, d50 of the low-voltage side in the double break was 65% higher than that of the same VI in the single break, which could be caused by the asynchronous property of mechanical actuators, the difference of the inherent prestrike characteristics of each VI and the unequal voltage-sharing ratio of VIs.

Numerical Simulation of Impact Effect of Internal Gas Pressure on Chamber Housing in Low-Voltage Circuit Breaker

2014 ◽  
Vol 4 (4) ◽  
pp. 632-640 ◽  
Author(s):  
Lijun Wang ◽  
Hongwu Liu ◽  
Wensong Zheng ◽  
Chonglong Ge ◽  
Ruiliang Guan ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Low Voltage ◽  
Circuit Breaker ◽  
Gas Pressure ◽  
Impact Effect

3D Thermal Analysis of a Power Supply Busbar Structure

2010 ◽  
Author(s):  
Adrian Plesca ◽  
Alina Scintee
Keyword(s):  
Thermal Analysis ◽  
Power Supply ◽  
Low Voltage ◽  
Circuit Breaker ◽  
Convective Heat Exchange ◽  
Point Of View ◽  
Circuit Breakers ◽  
Transient Thermal ◽  
Supply Systems ◽  
Electrical Apparatus

Busbar technology is more and more used to realize connections within power supply systems in answer to the need of compactness. The integrated problem on heat conduction and radiation-convective heat exchange describes the temperature regime in current conductors and current carrying busbars of power electrical apparatus such as circuit breakers or high breaking capacity fuses. Beside steady-state conditions, the transient thermal regime of busbar has an important influence upon whole power supply system from thermal behaviour point of view. Hence, a 3D thermal analysis of a power system including fuse, low voltage circuit breaker and busbars connections, using a specific software package based on Finite Element Method, has been done. From 3D thermal modelling and simulations, the thermal transient impedance for the busbar has been computed. This allows a better correlation between protection characteristics of the fuse and circuit breaker and busbar design.

scholarly journals Towards an Efficient Arc Simulation Framework

2017 ◽  
Vol 4 (1) ◽  
pp. 79-82 ◽  
Author(s):  
R. Fuchs ◽  
M. Mürmann ◽  
H. Nordborg
Keyword(s):  
Reference Data ◽  
Low Voltage ◽  
Circuit Breaker ◽  
Test Case ◽  
Simulation Framework ◽  
Root Model ◽  
Coupled Solution ◽  
And Control ◽  
Arc Root

Arc simulations require a coupled solution of the flow and electromagnetic equations. Despite of industrial interest, there is no established simulation framework available yet. We assess the usability of STAR-CCM+ for low voltage circuit breaker simulations using a test case of a model arc chamber, since this toolkit allows to define and control the simulation in a single environment. In spite of a partially implemented arc root model, the results agree well with reference data of previous publications.

scholarly journals Decentralized Plug-and-Play Protection Scheme for Low Voltage DC Grids

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3167
Author(s):  
Nils H. van der Blij ◽  
Pavel Purgat ◽  
Thiago B. Soeiro ◽  
Laura M. Ramirez-Elizondo ◽  
Matthijs T. J. Spaan ◽  
...  
Keyword(s):  
Solid State ◽  
Fault Detection ◽  
Low Voltage ◽  
Circuit Breaker ◽  
Circuit Breakers ◽  
Plug And Play ◽  
Zero Crossing ◽  
Protection Scheme ◽  
Selective Protection ◽  
Solid State Circuit Breaker

Since the voltages and currents in dc grids do not have a natural zero-crossing, the protection of these grids is more challenging than the protection of conventional ac grids. Literature presents several unit and non-unit protection schemes that rely on communication, or knowledge about the system’s topology and parameters in order to achieve selective protection in these grids. However, communication complicates fast fault detection and interruption, and a system’s parameters are subject to uncertainty and change. This paper demonstrates that, in low voltage dc grids, faults propagate fast through the grid and interrupted inductive currents commutate to non-faulted sections of the grid, which both can cause circuit breakers in non-faulted sections to trip. A decentralized plug-and-play protection scheme is proposed that ensures selectivity via an augmented solid-state circuit breaker topology and by utilizing the proposed time-current characteristic. It is experimentally shown that the proposed scheme provides secure and selective fault interruption for radial and meshed low voltage dc grids under various conditions.

scholarly journals Circuit Breakers in Low- and Medium-Voltage DC Microgrids for Protection against Short-Circuit Electrical Faults: Evolution and Future Challenges

2021 ◽  
Vol 12 (1) ◽  
pp. 15
Author(s):  
Bayron Perea-Mena ◽  
Jaime A. Valencia-Velasquez ◽  
Jesús M. López-Lezama ◽  
Juan B. Cano-Quintero ◽  
Nicolás Muñoz-Galeano
Keyword(s):  
Low Voltage ◽  
Short Circuit ◽  
Circuit Breaker ◽  
Circuit Breakers ◽  
Medium Voltage ◽  
Advantages And Disadvantages ◽  
General Terms ◽  
Future Challenges ◽  
Electrical Faults ◽  
Medium Voltage Dc

This paper deals with circuit breakers (CBs) used in direct current microgrids (DCMGs) for protection against electrical faults, focusing on their evolution and future challenges in low voltage (<1.5 kV) and medium voltage (between 1.5 kV and 20 kV). In recent years, proposals for new circuit-breaker features have grown. Therefore, a review on the evolution of circuit breakers for DCMGs is of utmost importance. In general terms, this paper presents a review concerning the evolution of circuit breakers used in DCMGs, focusing on fuses, mechanical circuit breakers (MCBs), solid-state circuit breakers (SSCBs), and hybrid circuit breakers (HCBs). Their evolution is presented highlighting the advantages and disadvantages of each device. It was found that although modern circuit breakers have begun to be commercially available, many of them are still under development; consequently, some traditional fuses and MCBs are still common in DCMGs, but under certain restrictions or limitations. Future challenges that would allow a successful and adequate implementation of circuit breakers in DCMGs are also presented.

scholarly journals Aging Characteristics of Contact Electrodes of Low Voltage DC Switches

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6838
Author(s):  
Hyosung Kim
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Low Voltage ◽  
Voltage Drop ◽  
Circuit Breaker ◽  
Zero Point ◽  
Circuit Breakers ◽  
Load Current ◽  
Dc Distribution ◽  
Test Operation

With the present state of the direct current (DC) distribution market, securing the safety of the DC distribution system is emerging as a major issue. Like AC distribution systems, DC switches and circuit breakers are one of the main means to ensure safety. However, in the DC system, since there is no current zero point in the load current, the phenomenon occurring when the circuit is cut off is different from that of the AC system, so technical research is required to cope with this. In this study, the aging characteristics of the contact electrode of a 400 V class low voltage DC (LVDC) switch is studied for the development of wall-mount switches or circuit breakers for residential houses. As an arc extinguishing method to break DC load current, a prototype experimental circuit breaker that uses a magnetic extinguishing method that is effective for blocking low voltage low power DC is invented, and an automated experiment system is established. The DC switch test repeats the operation of turning it on and off 13,000 times, and continuously evaluates the performance of the electric contacts by calculating the voltage drop between the electrode contacts and the corresponding Ohmic resistance value when conducting every 500 times. This paper tests six contact materials to compare the aging characteristics of them by evaluating contact resistance during the test period. AW18-Cu composite material showed the most stable and excellent contact performance for LVDC switches during the entire test operation period.

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