Current transfer between two parallel electrical arcs

Section: Study Of the Re-strikingmentioning

confidence: 79%

Evolution of a low-voltage electric arc

Mercier

Cajal

Laurent

et al. 1996

“…The conductance-probe measurement is the most widespread technique to demonstrate that a medium is still conductive [2,3,12]. However, deriving a gas temperature from it is difficult.…”

Section: Arc Re-strike Mechanismmentioning

confidence: 99%

Optical diagnostics and numerical modelling of arc re-strikes in low-voltage circuit breakers

Fievet

Barrault

Petit

et al. 1997

This paper is devoted to the study of the phenomenon of arc re-striking in low-voltage circuit breakers. The arc re-strike can be described as a sudden re-appearance in the arcing contact region when the arc had been situated in the quenching chamber a few tens of microseconds before. Our experimental investigations have established that the critical arcing contact region is still crossed by a so-called residual current of the order of several amperes. A gas temperature of around 4000 K was derived both from fine electrical measurements and from a molecular spectroscopy technique just before the occurrence of the arc re-strike. We also demonstrate that the re-strike takes place through the growth of the remaining current of several amperes in the arcing contact region. A numerical approach was carried out with a two-dimensional hydrodynamic code. This was found able to describe the arc movement in the model circuit breaker throughout a high-current-interruption operation and, notably, to simulate the arc re-strikes. The simulation exhibits the role of the flow of gas evaporated from the wall in the process of maintaining a slightly conductive medium in the arc ignition region.

“…The important values of the electric field explain that the arc always re-strikes between the bottom of the splitting plate and one of the electrodes. In fact, Haug et al showed that re-strikes are more frequent when the distance between electrodes is small [12]. Moreover, note that re-strikes take place during the decreasing phase of the current.…”

Section: Re-strike Characterizationmentioning

confidence: 99%

Study of re-strike phenomena in a low-voltage breaking device by means of the magnetic camera

Debellut¹,

Gary²,

Cajal³

et al. 2001

To preserve the qualities of the contacts of a circuit breaker, an important phenomenon to be valued is the arc motion. In this paper, the behaviour of a high-current and low-voltage electric break-arc is studied thanks to a means of diagnostics called `magnetic camera'. One hundred probes measure the magnetic induction outside the breaking device. A processing software reconstructs the average line of current representing the arc with a 0.64 µs minimal resolution time, the line being assumed to be composed of segments. The presented study deals with the analysis of a harmful phenomenon for the circuit breaker: the re-strike during which several arcs exist. Tests have been carried out in a quenching chamber composed of a copper or steel splitting plate with an assumed peak current of 4000 A. One of the main difficulties of this study taking into consideration the magnetic effects due to steel splitting plates. Actually, we show that they have a slight influence on the location of the line of current. Thanks to the `magnetic camera', the arc positions and their respective intensity values are both determined. Besides, differences in behaviour have not been noticed between the use of a copper and a steel splitting plate.