Experimental Research on DC Interruption Characteristics of Vacuum Interrupter by Forced Current Zero

Post-arc current measurement and interruption performance of vacuum interrupter in DC interruption

“…Hence the residual charges are depleted from the contact gap quickly, which leads to a high peak PAC. A linearity relation between the di/dt at CZ and the RRITIV is observed in [9]. So that the dependence of PAC on di/dt and du/dt is unified to dependence on di/dt only.…”

“…The scatter deviates from the measured peak PAC in figure 6 remarkably. We modified the model by substituting the average di/dt with the instantaneous di/dt at CZ and substituting the current decay time with a memory time of 4.5 µs, which was proposed in our previous work [9]. The arcing memory time means that the arcing current before this time has no influence on the post-arc current.…”

“…Based on our previous work in paper [9], this paper contributes to provide new experiment results to support the finding of the arcing memory time, which is based on mathematical models describing the residual plasma density and its influence on the PAC. To explain the influence of electrode separation on PAC, the continuous transient model (CTM) is adopted, in which model the electrode separation is connected to the PAC by the initial residual plasma density.…”

“…The experiments were conducted with a test circuit shown in figure 1, of which detailed description can be found in [9] besides technical parameters of the tested vacuum interrupter in [8]. To facilitate measurement of current in a large dynamic range extending from milli-amperes to tens of kilo-amperes, a special Rogowski coil named M coil is applied in the experiment, together with a high voltage probe for measuring the voltage across the VCB and a data acquisition system isolated by optic fibre to make up a current zero diagnostic system.…”

“…Experiments were carried out to investigate the development of the PAC and ITIV after the forced CZ [8]. It is concluded in [8] and [9] that the arcing current beyond a certain time interval before the current zero has no influence on PAC. Based on the experiment results, the memory time of the PAC was found to be no more than 4.5 µs.…”