Analysis of Pressure Rise in a Closed Container Due to Internal Arcing

Abstract

Abstract:When an arc fault occurs in a medium-voltage (MV) metal enclosed switchgear, the arc heats the filling gas, resulting in a pressure rise, which may seriously damage the switchgear, the building it is contained in, or even endanger maintenance personnel. A pressure rise calculation method based on computational fluid dynamics (CFD) has been put forward in this paper. The pressure rise was calculated and the arc tests between the copper electrodes were performed in the container under different gap lengths by the current source. The results show that the calculated pressure rise agrees well with the measurement, and the relative error of the average pressure rise is about 2%. Arc volume has less effect on the pressure distribution in the container. Arc voltage Root-Mean-Square (RMS) has significant randomness with the change of arc current, and increases with the increase of gap length. The average arc voltage gradients measure at about 26, 20 and 16 V/cm when the gap lengths are 5, 10 and 15 cm, respectively. The proportion (thermal transfer coefficient k p ) of the arc energy leading to the pressure rise in the container is about 44.9%. The pressure is symmetrically distributed in the container before the pressure wave reaches the walls and the process of the energy release is similar to an explosion. The maximum overpressure in the corner is increased under the reflection and superimposition effects of the pressure wave, but the pressure waves will be of no importance any longer than a few milliseconds in the closed container.

Influence of buffer volume on the effect of pressure relief for the metal‐enclosed switchgear due to arc fault

“…When the U c is fixed to 7 kV, the waveforms of arc voltage and current for different models are obtained, and the parameters of arc voltage and current are given in Table 2. The calculation method of the arc voltage root mean square (RMS) can refer to [17]. It can be seen that the parameters of arc voltage and current are basically the same for models M1, M2, and M3, and the maximum relative error of the arc energy in different models is only about 5%, which indicates that the arcing experiments have good repeatability.…”

Explainable artificial intelligence modeling of internal arc in a medium voltage switchgear based on different CFD simulations

“…The domain of solving will be divided into small cells and then coupled mass, momentum, and energy equations will be solved [ 22 ]. To solve the above equations, the ideal gas equation which relates the density of gas with its temperature and pressure should be involved [ 8 , 23 ].…”