High Current Arc Erosion on Copper Electrodes in Air

Abstract

An arc fault inside metal enclosed switchgear will cause the pressure to rise and vaporization of electrode material may contribute to the pressure rise. An experimental study of high current arc erosion on copper electrodes in air has been performed, with an evaluation of fraction lost by gross melting and vaporization. All experiments were performed at NEFI High Voltage Laboratory in Skien, Norway. The measured mass loss from vaporization in our experiments seems to be negligible compared to erosion by gross melting.

Investigation into limitation of electric arc energy in LV switch installed in AC circuit through application of time-controlled contact separation

“…As it can be observed in the measured waveforms, a high steepness of the current (over 40 A/ms) is observed between the time of the contacts separation and before the current zero-crossing. So high the di/dt steepness causes to generate significant switching overvoltages, which can be observed in the arcing voltage, and in the TRV peaks in (see Figures 5,6). This phenomenon is related to the weak ionization conditions of the gas localized between the separated contacts of the operated switch: the relatively small value of the electric field and the small instantaneous value of the interrupting current, insufficient to achieve the significant temperature rise between the contact surfaces, which is necessary to obtain the powerful gas ionization.…”

“…Therefore, finding an effective way for the limitation of the arc erosion is a complex issue. To limit the electric arc erosion in the considered switch, the electrical arc energy should be limited during the current interruption process . For this purpose, various methods for more effective arc quenching that are focused on the design of switches are being developed (e.g.…”

“…For this purpose, various methods for more effective arc quenching that are focused on the design of switches are being developed (e.g. an optimization of parameters of the quenching arc chamber, an application of an appropriate shape of the contacts, and a suitable type of the contact material) . On the other hand, there are electrical methods for limiting the electrical arc energy that are based on a connection of parallel branches to the operated switch .…”

“…an optimization of parameters of the quenching arc chamber, an application of an appropriate shape of the contacts, and a suitable type of the contact material). [6][7][8][9][10][11][12][13] On the other hand, there are electrical methods for limiting the electrical arc energy that are based on a connection of parallel branches to the operated switch. [14][15][16][17][18] In AC systems, the A list of the symbols: e S , the energy of the electric arc [J]; i S , interrupting current [A]; p A , the power of the electric arc [W]; u N , the voltage of the voltage source [V]; u S , the measured voltage across the operated switch [V]; t 0 , time, when the contacts of the operated switch start to separate [ms]; TRV, Transient Recovery Voltage [V]…”

Energy based evaluation of gas cooling related to arc faults in medium voltage switchgear

“…The thermal transfer coefficient or "k p -factor", defined as the fraction of arc energy causing the pressure rise (until disc rupture), was 0.44. Energy required for heating, melting, and vaporizing the electrodes, "electrode arrangement", in Figure 7, is based on Oyvang et al [4]. The maximum temperature recorded at the surface of the arc compartment (T 11 ) was about 373 K. Assuming that effectively about 75 % of the total mass of the 100 kg arc compartment is heated to this temperature, the energy required is about 3000 kJ, or approximately 2/3 of the total energy input.…”