1. National Institute of Metrology, Beijing 100029, China
2. Xi′an Institute of Measurement and Testing Technology
Xi′an, Shaanxi 710068,China; 3. Hunan Institute of Metrology and Test, Changsha, Hunan 410014, China
Abstract：The historical verification datum of an amount of reference Pt/Rh10-Pt thermocouples from multiple institutes are statistically inspected . The thermocouples were observed of stable thermoelectric characteristic that the annual mean of the emf drift close to 0μV at freezing fixed points of Cu, Al, Zn with standard deviation 1.0μV,0.6μV and 0.4μV respectively. The histograms of datum at fixed points were nearly normal distribution; the annual emf drift characteristic of individual thermocouple at fixed point appeared in strong biserial correlation. The emf of those thermocouples was observed slightly increasing with time. The inspection demonstrated under the normal condition that no correlation existed between emf drift and frequency in use.
2015, Vol. 36 
