Author:Gary Bennett – National Instruments Metrology Laboratory Manager
description
Transcript of Author:Gary Bennett – National Instruments Metrology Laboratory Manager
NCSLI 2013 Conference1
How to Achieve a 0.01 µV/V Deviation on Your 10 Vdc Proficiency Test
Without using a Josephson Array
Author: Gary Bennett – National InstrumentsMetrology Laboratory Manager
Speaker: Jorge Martins – National InstrumentsPrincipal Metrology Engineer
NCSLI 2013 Conference2
Learning Objectives
• Activities required to maintain a 10 Vdc reference standard
• Tools available to make precision 10 Vdc transfer measurements
• Overview of techniques to track measured values and project future values of precision standards
NCSLI 2013 Conference3
Opportunity for Internal Support
Need to perform artifact calibrations on Fluke 5720A to maintain the 90 day specifications
• Purchased:– 4x 10 Vdc Reference Standards– Data Proof VoltRef SW and 160B scanner– Nanovoltmeter
NCSLI 2013 Conference4
Requirements
30 Days 90 Days 1 Year10 V 0.3 0.8 2.0
Stability (± µV/V)Output Voltage
10 Vdc uncertainty for calibrator adjustment is:±1.5 µV/V
10 Vdc Reference Stability Specification
NCSLI 2013 Conference5
Options• Expand the 90 day specification of the 57x0 as
per mfg. manual
• Shorten interval of 10 Vdc Zener references
• Buy a 10 Vdc with history … that you can trust!
• Devise a process to expedite the characterization of our Zener References
NCSLI 2013 Conference6
NCSLI 2013 Conference7
NCSLI 2013 Conference8
Our Chosen Method
• Calibrate all 4 using MAP program after six months.– Measure the travelling standard
• Create procedure to measure the travelling standard• Review the previous 6 months of VoltRef data• Determine uncertainty
– Measure all our 10 Vdc references against the travelling standard using the MAP provider’s procedure
NCSLI 2013 Conference9
Measurements Prior to 2nd Calibration
NCSLI 2013 Conference10
Result of 1st Proficiency Test
NCSLI 2013 Conference11
What Happened?
NCSLI 2013 Conference12
2nd Calibration
NCSLI 2013 Conference13
2nd Calibration Results
NCSLI 2013 Conference14
3rd Calibration 2nd Proficiency Test
NCSLI 2013 Conference15
3rd Calibration, 2nd Proficiency Test
NCSLI 2013 Conference16
Proficiency Test #2
NCSLI 2013 Conference17
Projected Values and 3rd Calibration
NCSLI 2013 Conference18
3rd Calibration
NCSLI 2013 Conference19
Proficiency Test #3
NCSLI 2013 Conference20
4th Calibration
NCSLI 2013 Conference21
Proficiency Test #4
NCSLI 2013 Conference22
5th Calibration
NCSLI 2013 Conference23
5th Calibration Cell #1
NCSLI 2013 Conference24
Uncertainty Components
• Calibration Uncertainty (Travelling standard)• Atmospheric Pressure• Temperature• Noise• Type A Statistical • Uncertainty of Projected Value• Hysteresis Error
NCSLI 2013 Conference25
Conclusion• VoltRef works very well with the proper drift
information for each cell• Tools are available to make the data gathering
less painful• Understanding the normal differences in
performance of individual references is important• Gathering history on reference standards is
expensive
NCSLI 2013 Conference26
Questions