ASTM D4496-13 pdf free download.Standard Test Method for D-C Resistance or Conductance of Moderately Conductive Materials.
ASTM D4496-13 is useful for the comparison of materials, as a quality control test, and for specification purposes.
ASTM D4496-13 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.
4. Summary of Test Method
4.1 Specimens of the test material are conditioned at prescribed conditions and subjected to direct-voltage stress. Resistance or conductance is measured and used with the dimensional aspects of the specimen to compute the resistivity of the material. The apparatus and techniques used in this test method are selected in accordance with the general principles set forth in Test Methods D257.
5. Significance and Use
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.
7. Specimen Preparation and Selection
7.1 Take specimens from a sample of material that has been obtained in a random manner. Take care to protect the sample and the specimens from any contamination, which will affect the results of the resistance or conductance tests. Such contamination can include, in particular, salts or moisture from human hands. Be aware of elevated temperatures. extremes of high or low humidity. and the presence of chemical vapors. etc.
7.2 Prior to testing, condition all specimens to equilibrium in the standard laboratory atmosphere prescribed in Practice D6054. For many materials the time of conditioning to equilibrium will require only a few hours (that is. less than 24 h). Equilibrium with standard laboratory conditions is declared attained if two consecutive volume resistance measurements on the same specimen agree within ± 1 %. The two consecutive measurements are to he made at the intervals separated at least by4h.