1,721,027 research outputs found
Review of arcing phenomena in low voltage current limiting circuitbreakers
No full textLow voltage current limiting circuit breakers referred to as miniature circuit breakers (MCBs) are widely used for electrical fault protection in domestic and light industrial installations. Modern designs employ current limiting technology where the arc is forced rapidly away from the contacts through an arc chamber and into a set of splitter plates. The motion of the arc is dependent on a complex interaction of the anode and cathode root and the arc plasma motion. There is a large volume of published research work relating to the study of arc phenomena. The paper presents a selective review of the significant work relevant to the study of arc phenomena in MCBs under short circuit conditions. Studies of arc column, arc root and arc electrode effects, and the physics of arc motion as well as developments in the study of arc motion and arc control in MCBs, are reviewed
Integrated measurement system for high speed unsteady plasma flow and its application to electric arcs
No full textAn integrated measurement system for the study of high speed and high temperature unsteady plasma flows, such as those found in the vicinity of high current switching arcs, is presented. An optical high-speed imaging system is integrated with pressure sensing and spectroscopic measurement to gain insight into the complex unsteady flows in applications such as circuit breakers and internal combustion engines. The system permits direct and non-intrusive measurement to obtain new data on these transient events, which occur over a period of a few milliseconds. The imaging system captures at a rate of 1000 000 images per second. Software techniques have been developed to control light sensitivity, to generate dynamic images of the high-speed flows; to measure trajectories, times, velocities, pressure change, and to analyse gaseous composition in the tested device simultaneously. The range of applications for this system is very wide. For demonstration purposes, a study of the electric arcing process within a low-voltage circuit breaker and an aeroplane engine ignition unit is presented. This is the first time that a system has been developed to provide detailed measurement of arc root immobility time and arc motion
Gas flow and composition effects on arc motion in current limiting circuit breakers
No full textArc motion in low voltage (240 VAC) high current (103-104 A) current limiting circuit breakers is dominated by arc root mobility. This is strongly affected by the gas flow and gas composition in the contact region, but there is little experimental data on these effects. New pressure and spectral data measurement during arc movement are presented using a flexible test apparatus and an arc imaging system. These measurements are used to investigate gas flow characteristics in the arc chamber. The chemical and physical phenomena occurring during the arc motion are discussed. The combination of optical and spectral data provides new insight into the arc motion. Also studied are the influences of arc chamber material, contact material, and contact opening speed. These data are used to improve arc control for a low contact opening velocity of 1 ms-1
Arc motion and gas flow in current limiting circuit breakers operating with a low contact switching velocity
Full text linkArc motion in low voltage (240 VAC) high current (10/sup 3/-10/sup 4/A.) current limiting-circuit breakers is dominated by arc root mobility. The mobility is influenced by the gas flow and gas composition in the contact region, but there is little experimental data on these effects. New pressure and spectral data measurement during arc movement are presented using a flexible test apparatus and an arc imaging system. These measurements are used to investigate gas flow characteristics in the arc chamber. The chemical and physical phenomena occurring during the arc motion are discussed. The combination of optical and spectral data provides new insight into the arc motion. The influences of arc chamber material, contact material, and contact opening speed, are investigated to improve arc control for a low contact opening velocity
Arc root mobility on piezo-actuated contacts in miniature circuit breakers
No full textA novel contact opening mechanism has been developed using a piezo-ceramic actuator to open the contacts in a low contact opening velocity circuit breaker. The arc control on the contacts is critical for successful current interruption (103-104 A) in low voltage (<250V) devices. Previous work has shown how arc root commutation from the contact region into the arc chamber is affected by arc chamber materials, contact materials and the gap behind the moving contact for contact velocities in the range 10 ms-1 and 1 ms-1.This work is further extended by using a commercially available piezo-ceramic actuator to open the contacts. Contact opening speeds are assessed and the arc root mobility is characterised under this operating regime. A flexible test apparatus is used to vary the arc chamber geometry. A solid-state high-speed arc imaging system and pressure transducers are used to gather data on the arc mobility and the gas dynamic interactions occurring during the piezo actuated contact opening. New experimental results are presented on arc root velocity, arc root motion, arc imaging and pressure measurement in the arc chamber with the piezo actuated contact opening. Results are correlated using a semi-empirical model of the arc motion. These results can be used to improve the design of high current low voltage circuit breakers suitable for piezo-ceramic actuation
Arc root mobility during contact opening at high current
No full textThis paper presents a test system, designed for the investigation of short circuit arcs related to miniature circuit breakers operating in a 240 V, AC supply. An optical fiber imaging system is used to identify arc root motion, with short circuit current up to 6 kA. Two methods are used to measure contact motion, a noncontact linear position sensor, and the optical fiber array. The optical fiber array uses software image processing to identify the position of the arc roots in the arc chamber. The identification of the arc roots allows for a study of the arc immobility at the initial stages of the event. Results are presented on variation of peak current level and arc runner materials on arc root motion for one geometry. The cathode root motion is shown to dominate the event
Electrode processes and arc form in miniature circuit breakers
No full textThe electric arc in current limiting circuit breakers is often depicted as a well defined region of current flow. During a short circuit fault the current through the arc in a current limiting miniature circuit breaker can range from 100 to 10000 Amps. This range of current, along with varying electrode conditions, will lead to variation in both the form of the arc and the processes occurring at the electrodes. These electrode processes, in particular the emission mechanism at the cathode root, dominate the mobility characteristics of the arc. Previously proposed electrode processes are reviewed and the interaction of the mechanisms discussed. Using data recorded on a high speed Arc Imaging System observations about the arc behaviour at different intervals of the arc event are related to possible electrode processes. The variation of arc form in miniature circuit breakers is also discussed
The energetics of gas flow and contact erosion during short circuit arcing
Full text linkThe processes governing the movement of short circuit arcs in circuit breakers are complex and variable and the detailed understanding of these processes is incomplete. This paper presents a new approach to our understanding of the short circuit arcing process by concentrating on the bulk thermal behavior and energetics of the arcing and gas flow during contact opening. It is shown how considerations of the arc power and the heating and vaporization of the contact material can be used to examine the flow of gas through the arc chamber and the erosion of contact material. Experimental data from a flexible test apparatus and arc imaging system along with measurements of pressure and arc current and voltage are used as the basis of the analysis. It is demonstrated how the air initially present in the arc chamber will be rapidly expelled from the arc chamber to leave an arc burning in the products of contact volatilization. Data on mass and volume flow rates are presented as well as estimates of the gas velocity in the contact region. These data provide information on the nature of the gas flow in the arc chamber as well as contact erosion during the arcing process. Arcing conditions of interest are short circuit faults (103-104 A) in low voltage (220-380 VAC) circuit breakers
Arc root mobility during contact opening at high current
No full textThis paper presents a test system, designed for the investigation of short circuit arcs related to miniature circuit breakers operating in a 240 Volt, ac supply. An optical fibre imaging system presented previously is used to identify arc root motion, with short circuit current up to 6kA. Two methods arc used to measure contact motion, a non-contact linear position sensor, and the optical fibre array. The optical fibre array uses software image processing to identify the position of the arc roots in the arc chamber. The identification of the arc roots allows for a study of the arc immobility at the initial stages of the event. Initial results are presented on the effect of supply polarity on arc root motion
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