DIN EN 61340-2-3:2017-05

Resistance measurements and the associated calculations of resistivity, together with voltage and current measurements, are among the fundamental tasks of electrical metrology. The resistivity is the electrical quantity with the largest range of values, extending over some thirty orders of magnitude (decades) from the most conductive metal to the almost perfect insulator. The basis for the measurements is Ohm's law, which is valid for direct currents and instantaneous values of alternating currents in electron conductors (metals, carbon and so on). Measured values based on resistance measurements with alternating current can be influenced by frequency-dependent capacitive/inductive reactance. Therefore, existing national and international standards dealing with resistance measurements on solid materials usually require the use of direct current. Most non-metallic materials, such as plastics, are classified as polymers and ionic conductors. The charge transport can depend on the existing electric field strength during the measurement. In addition to the measuring current, there is a charging current that causes polarization and/or electrostatic charging in the material, which is indicated by an asymptotic decrease in the measuring current over time and a resulting apparent change in the material resistance. If this effect is detected, it is advisable to repeat the measurement immediately after the specified measurement time has elapsed with the reverse polarity of the measuring current and to average the two measured values obtained. This Part 2-3 of the IEC 61340 "Electrostatic" series of international standards describes test methods for the determination of the electrical resistance and resistivity of solid materials in the range from ten-exponent-four ohms to ten-exponent-twelve ohms, used to avoid electrostatic charge accumulation. It takes account of existing IEC/ISO standards and other published information, and gives recommendations and guidelines on the appropriate method. The responsible committee is DKE/K 185 "Elektrostatik" ("Electrostatics") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.