Alignment uncertainties of the NIST watt experiment

Author

Gillespie, Aaron D. ; Fujii, Ken-ichi ; Newell, David B. ; Olsen, Paul T. ; Picard, A. ; Steiner, Richard L. ; Stenbakken, Gerard N. ; Williams, Edwin R.

Author_Institution

Electr. Div., Nat. Inst. of Stand. & Technol., Gaithersburg, MD, USA

Volume

46

Issue

2

fYear

1997

fDate

4/1/1997 12:00:00 AM

Firstpage

605

Lastpage

608

Abstract

The effects of alignment uncertainties of the NIST watt balance with respect to local gravity and the magnetic flux density of the balance have been analyzed. Techniques for measuring all quantities relevant to misalignment have been developed. The components of the relative combined standard uncertainty of the measured value of the watt due to alignment uncertainties have been reduced to 20 nW/W, and potential improvements in the balance design have been identified which could ultimately lead to a reduction of that uncertainty to below 10 nW/W

Keywords

balances; light interferometry; measurement errors; measurement standards; position control; power measurement; units (measurement); NIST watt experiment; alignment uncertainties; balance design improvement; laser interferometers; local gravity; magnetic flux density; misalignment; relative combined standard uncertainty; Angular velocity; Electric variables measurement; Force measurement; Magnetic flux density; Mechanical variables measurement; NIST; Superconducting coils; Uncertainty; Velocity measurement; Voltage;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.571933

Filename

571933