Guarded Hamon transfer standards are used at NIST for scaling to high resistance levels. An improved design for a guarded Hamon transfer standard in the range from 1 TΩ to 100 TΩ is described. Measurements taken to select the primary and guard resistor elements are described, as well as the process used to clean the resistor elements. The selection process for resistor elements focused on choosing the smallest settling times and narrowest range of corrections from nominal value. Key aspects of this guarded Hamon transfer standard are the elimination of charge-storing materials in its connections, selection of resistors to minimize leakage currents, and the hermetic sealing of all the elements inside one enclosure.
CPEM 2014 Conference Digest
August 24-29, 2014
Rio de Janeiro
Conference on Precision Electromagnetic Measurements (CPEM) 2014
Measurement, standard resistor, guarded Hamon transfer standard, settling time, scaling