Metrological characterization of a 1 N m torque standard machine at PTB, Germany

摘要

A few years ago, a 1 N m deadweight torque standard machine was developed, constructed and put into operation at PTB in Germany. Since then, this machine has been used for measurements, but also, investigations of its stability and reproducibility have been carried out. The machine utilizes calibrated stainless-steel masses as weights and a lever made of Invar which is supported by an H-type air bearing. The measurement range starts at 1 mN m. Depending on the weights used, various torque steps are possible. The best expanded (k = 2) relative uncertainty of measurement is 0.01%. In the following, technical details and metrological characteristics of this machine will be given.