The dielectric properties of non-conductors

✍ Scribed by Phillips Thomas

• Publisher: Elsevier Science
• Year: 1913
• Tongue: English
• Weight: 783 KB
• Volume: 176
• Category: Article
• ISSN: 0016-0032
• DOI: 10.1016/s0016-0032(13)90439-7

✦ Synopsis

THIS paper presents the results of an attempt to find some connection between the various electrical properties of certain insulating materials, and to secure evidence as to whether or not general relations hold between such properties of nonconductors as a class. The plan was to select, by preliminary tests, a few subs,tances that differ greatly in specific inductive capacity, and to make extensive and accurate tests on the materials chosen. The data thus found were to be reduced to some form permitting ready inter-comparison.

The materials chosen for test were mica, paraffined paper, celluloid, and ice. The dielectric constants of these substances range from about 4 to about ioo, when measured by alternating current o,f high frequency. The tests were made upon condensers having these materials as dielectrics, and were as follows :

(I) Tests of capacity and power-factor at high frequencies.

(2) Tests of insulation resistance by direct current, and of capacity on very short times of charge.

(3) Tests of the breakdown strength of portions of the dielectrics, removed from the condensers.

(4) Tests upon the change in capacity, due to varying the direct voltage applied to the condensers.

The condensers tested, with the exception of that in which ice was the dielectric, were parallel plate condensers of the ordinary type, and consisted of a number of sheets o.f dielectric, separated by sheets o.f conducting material, the whole being impregnated with paraffin and placed under pressure until the paraffin was nearly all crowded out. The mica condenser had not been so treated, however: in this case the leaves had been simply stacked without permanent compression and without paraffin.