Complete characterization of Zener standards at 10 V for measurement assurance program (MAP)

A complete characterization of Zener standards for temperature, pressure, and humidity is being performed to improve the uncertainty of a measurement assurance program (MAP) that uses 10 V Zeners as travelling standards. The procedure and equipment used for this work is briefly described. For the Zener standards we have tested, the temperature coefficients range from (1.6 to 5.4) nV//spl Omega/ expressed by Zener output change versus thermistor resistance, and the pressure coefficients range from (1 to 20) nV/hPa. The time constant of Zener response to relative humidity change varies from days to nearly infinity. By choosing low noise and nonhumidity sensitive Zeners as transfer standards and correcting for the pressure and temperature effects, the uncertainties of a MAP can be improved.