As the salts of multi-valent cation, AlCl3 Al2 (SO4) 3 and Th (NO3) 4 were selected, and effects of these on dielectric properties of un-impregnated paper and oil impregnated paper were studied.
(1) In regard to the dielectric loss of un-impregnated paper at high temperature, all the papers treated with solutions of less concentration than 2.5 x10-4 N were more excellent than the papers washed once with cure water.
In the range of that concentration, the order of the dielectric loss at high temperature w as as follows : Th (NO3) 4> AlCL3> Al2 (SO4) 3, but in the concentration of more than 1 x 10-3N, the order was
AlCl3>Al2 (SO4) 3>Th (NO3) 4.
(2) In regard to the dielectric loss of oil impregnated paper at 100T. the order of dielectric loss was as follows : AlCl3>Al2 (SO4) 3>Th (NO3) 4.
But, only two samples, which were treated with dilute solution of Th (NO3) 4, showed better result than the paper washed with pore water.
(3) Effects of multi-valent cation on the dielectric loss at 20°C of oil impregnated paper could he ignored.
(4) When the effects of cations (from mono-Nalent to tetra-valent) used in this work were compared .AlCl3and Al2 (SO4) 3were excellent in the dielectric loss of un-impregnated paper, but in dielectric loss of oil impregnated paper, they were not so much excellent, and Pb (CH3COO) 2was best and Th (NO3) 4was corn paratively good.