【国外标准】 Standard Test Method for D-C Resistance or Conductance of Moderately Conductive Materials

5.1 This test method is useful for the comparison of materials, as a quality control test, and for specification purposes.5.2 This test method is useful in the selection and use of materials in wires, cables, bushings, high-voltage rotating machinery, and other electrical apparatus in which shielding or the distribution of voltage stress is of value.5.3 Commercially available “moderately conductive” materials frequently are comprised of both conductive and resistive components (that is, cellulose fibers with colloidal carbon black particles attached to portions of the surfaces of those fibers, or discrete conductive particles adhered to the surfaces of electrical insulating polymers). Such commercially available materials are often manufactured in a manner that results in anisotropy of electrical conduction. Hence, the significance of tests using this test method depends upon the orientation of the specimen tested to the direction of the electric field and the relationship between this orientation and the orientation of the material in the electrical apparatus, which uses these materials.1.1 This test method covers the determination of electrical resistance and electrical resistivity of materials that are generally categorized as moderately conductive and are neither good electrical insulators nor good conductors.1.2 This test method applies to the materials that exhibit volume resistivity in the range of 100 to 107 Ω-cm or surface resistivity in the range of 103 to 107 Ω (per square).1.3 This test method is designed for measurements at standard conditions of 23 °C and 50 % relative humidity, but its principles of operation can be applied to specimens measured at lower or higher temperatures and relative humidities.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 8.3.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.