Traceability Link
Portable measuring instrument used to compare a primary standard in a reference laboratory with a secondary standard in another location. Metrology chains rely on a transfer standard to maintain the continuity of measurement units without moving delicate primary apparatus. It facilitates the dissemination of the volt or the ohm from a national metrology institute to a secondary calibration facility.
This device must possess exceptional short term stability and be rugged enough to survive transportation.
Performance Stability
Resistance to environmental changes and mechanical shock ensures that the calibration value remains valid during the move. A transfer standard is characterized by its low drift rate and high repeatability. Before and after the transfer, the unit is checked against a local reference to confirm that its properties have not changed.
Interlaboratory Comparison
Organizations use these devices to participate in round robin testing where several laboratories measure the same artifact. The data from the transfer standard allow for the calculation of the agreement between results.
Calibration Cycle
Intervals between checks are determined by the historical stability of the instrument and the required uncertainty of the measurements. A transfer standard requires a detailed history of its performance to predict its behavior during a comparison. Historical data guide the calibration cycle.
