Method for determining the electric strength of insulation materials in small-volume cells

The paper is devoted to the development, validation, and assessment of the applicability limits of a method for determining the dielectric strength of insulating material samples with a volume of several milliliters. For experiments with microcells, a SKAT-70M power source with a specified output test voltage rise rate of 0.5 kV/s in automatic mode was used, which ensured a constant temperature regime for the studied samples in different experiments. Limiting the extent of sample structure destruction was achieved by reducing the average value of current through the breakdown channel, for which a resistor with a resistance of 100 MΩ was used. Statistically (with a significance level of 0.05), it was proven that tests in microcells of the proposed design are equivalent to similar tests according to the requirements of GOST 6581-75 for polymethylsiloxane PMS-10000 and transformer oil. The microcell testing technique allows for a significant (from 0.3 l to several ml) reduction in the volume of the test material for liquid and gel-like dielectrics. The key requirements for the geometric dimensions of the microcell and the materials used in its construction are examined. In particular, the possibility of 3D-printing microcells is discussed. For transparent materials, it is also possible to record processes in transmitted light during and after electrical breakdown. The primary application of this technique is laboratory testing of new materials, where sample volume reduction becomes critical.