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DATA PROOF in Working together with leading
laboratories around the world, we have identified a
variety of automated systems that optimize results for
methods implemented in as many laboratories as
possible. This paper presents various methods for
measuring voltage, resistance and temperature with
uncertainties below 1 ppm. In each case the goal of
automation is not simply to save labor, but also to
improve accuracy as well.
Substantial progress has been made in automating test
systems over the past quarter century. However, they
have not been useful for maintaining reference
standards due to the lack of suitable switches. Most
computer controllable switches generate thermal offsets
of about a microvolt. A scanner with very low thermal
offsets is now available that makes possible many
exceptional improvements in automating precision
measurements. The scanner used to achieve these
results has thermal offsets typically below 20 nanovolts.
It has a high leakage resistance of only 1012 ohms, or
as high as 1014 ohms for the guarded version of the
scanner.
The scanner is presently being used together with a
commercial software package, to maintain the volt in
hundreds of standards laboratories around the world
including the national laboratories of most industrialized
nations. Although the scanner was designed for making
voltage comparisons, more recently it is being precision
measurements as well. Over the last few years, much
innovative work has been done to automate
precision temperature and resistance measurements.
Several methods are achieving errors as low as 0.1
ppm. This paper reviews some recent innovations so
that others can use these techniques to improve the
uncertainties in their laboratories.
laboratories around the world, we have identified a
variety of automated systems that optimize results for
methods implemented in as many laboratories as
possible. This paper presents various methods for
measuring voltage, resistance and temperature with
uncertainties below 1 ppm. In each case the goal of
automation is not simply to save labor, but also to
improve accuracy as well.
Substantial progress has been made in automating test
systems over the past quarter century. However, they
have not been useful for maintaining reference
standards due to the lack of suitable switches. Most
computer controllable switches generate thermal offsets
of about a microvolt. A scanner with very low thermal
offsets is now available that makes possible many
exceptional improvements in automating precision
measurements. The scanner used to achieve these
results has thermal offsets typically below 20 nanovolts.
It has a high leakage resistance of only 1012 ohms, or
as high as 1014 ohms for the guarded version of the
scanner.
The scanner is presently being used together with a
commercial software package, to maintain the volt in
hundreds of standards laboratories around the world
including the national laboratories of most industrialized
nations. Although the scanner was designed for making
voltage comparisons, more recently it is being precision
measurements as well. Over the last few years, much
innovative work has been done to automate
precision temperature and resistance measurements.
Several methods are achieving errors as low as 0.1
ppm. This paper reviews some recent innovations so
that others can use these techniques to improve the
uncertainties in their laboratories.
| available methods spread throughout the worlds measurement community. |
* Simplified Voltage Scaling System * 10-Volt Josephson Junction Array Resistance Measurements * OhmRef: Software * Ring Method for Standard Resistors * Guarded High-Ohm Resistance System Temperature Measurements * Thermocouple Calibration System * Simplified System for Thermocouple Comparisons * PRT Comparisons |
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