Improving the mechanical stability of a standard capacitor

Abstract

The CSIR - NML (Council for Scientific and Industrial Research, National Metrology Laboratory) of South Africa, manufactured a 10-pF ultra-low expansion quartz capacitors in the early 1970s. Although the capacitors were extremely stable and had low temperature coefficients of capacitance, they were susceptible to mechanical shock. During 1999, a project was initiated to improve the mechanical stability of the capacitors after two capacitors were damaged during transit, while being transported as separate airfreight packages at the beginning of an international intercomparison. The assembly of a capacitor of improved design was completed in April 2001 and the capacitor was subjected to various tests to determine its robustness, thus a development of a standard capacitor with improvements to increase its robustness is presented. The capacitor withstood the tests to which it was subjected and the objective of the project to improve the mechanical stability was met. The results of the mechanical test show that the new capacitor design has improved its characteristics and its mechanical stability.