Fluke RUSKA 7050, Руководство пользователя

Страница: 83 / 88

Summary of Specifications
Uncertainty Analysis
A
A-3
In this approach, it is important to define the level of confidence that all of the
uncertainty components are defined. For instance, all of the uncertainty specifications
that Fluke Calibration publishes are at the 2 sigma level which would be at a 95%
confidence level. Some manufacturers may state their uncertainty at different confidence
level and therefore, you would need to be able to convert from one to the other in order to
compare the two devices. For instance, if a manufacturer states that they have an
uncertainty of 0.005% FS and that the uncertainty is expressed at the 1 sigma level, then
it would be doubled to express it at the 2 sigma level (i.e. it would be an 0.01% FS device
at a 2 sigma or 95% confidence level.)
The following two tables are uncertainty analysis examples for a 7050i based on a three
month and a yearly calibration.
Table A-1. Uncertainty Analysis for 7050i—Three Month Analysis
Uncertainty Analysis – 3 Month Calibration Interval
RUSKA 7050i from 25 to 100% of Range
Uncertainty
(2 sigma)
A. Performance – (Linearity, Hysteresis, Repeatability and Temperature) 0.005% of Reading
B. Stability – (3 months) 0.0019% of Reading per 90 days
C. Calibration Standard – (RUSKA 2465 DWG) 0.0010% of Reading
D. Environmental –
Temperature (Included in A. above) 0.000% of Reading
Head Pressure 0.001% of Reading
2 sigma Expanded Uncertainty (RSS) 0.0055% of Reading per 90 days
Table A-2. Uncertainty Analysis for 7050i—One Year Analysis
Uncertainty Analysis – One Year Calibration Interval
RUSKA 7050i from 5 to 100% of Range
Uncertainty
(2 sigma)
A. Performance – (Linearity, Hysteresis, Repeatability and Temperature) 0.005% of Reading
B. Stability – (1 year) 0.0075% of Reading / year
C. Calibration Standard – (RUSKA 2465 DWG) 0.0010% of Reading
D. Environmental –
Temperature (Included in A. above) 0.000% of Reading
Head Pressure 0.001% of Reading
2 sigma Expanded Uncertainty (RSS) 0.009% of Reading per year