放電におよぼす炭じんの影響

抄録

Various fundamental experiments were carried out on the influence of coal dust upon spark discharge, and, the experiments were performed under conditions as similar as possible to those in coal mines. The results-obtained were as follows:
(1) When coal dust is dropped on the electrode in a glass vessel, corona current increases and spark voltage decreases. The smaller the sizes of coal particles are, and the larger the quantity of the dropped coal dust is, the greater the effect will be.
(2) When DC voltage is impressed at the needle to plate electrode, the effect of polarity is remarkable, and this is considered to have certain bearings with the attached quantity of coal dust.
(3) When compared with other dusts, coal dust is observed to be particularly influential on spark discharge.
(4) On the influence upon surface discharge, of accumulated coal dust placed on the insulating plate: coal, dust in small quantity makes electric current increase and makes the break-down, voltage along the plate surface decrease, but as the quantity of coal dust increases, the current decreases, and the voltage increases.
(5) On the relation between the accumulated quantity of coal dust and the breake-down voltage along the plate surface: the break-down voltage shows the maximum value at a certain point of accumulated quantity of coal dust, and when the quantity is over that point, the voltage becomes decreased.