DC Arc Resistance Rise by PMMA Cylinder Ablation with Arc Shrinking in Silica Sand Filling Space

摘要

Concerning DC arc quenching phenomenon in silica sand filling space, we have proposed a new method for raising an arc column resistance (r(col)) by use of polymer-material arrangement. This paper reveals physical factors for r(col) rise on the bases of experimental results using the following cylinders made of: (i) Quartz (SiO2) and (ii) PMMA ((C5H8O2)(n)) with various inner diameters phi. For phi = 2 mm case, r(col) measured for a PMMA cylinder arrangement indicated higher r(col) at low current region, while almost same r(col) around current peak. For phi = 3 mm case, r(col) for the PMMA cylinder was lower than r(col) for the quartz case at high current region, while almost comparable between these conditions at low current region. For phi = 5 mm case, r(col) were almost same during the arc quenching process. To discuss the effect of the r(col) rise, the followings were also performed: (i) observation of cylinders after arc quenching and (ii) calculation of the electron density of SiO2/Cu or PMMA/SiO2 mixture vapors. It is concluded that, at high current region, r(col) can increase due to the shrinking of the arc conductive diameter caused by the cylinder hole and the silica sand filled inside the cylinder hole. On the other hand, the admixing of the PMMA ablation vapor increases r(col) at low current region in the present experiment. (c) 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.