1. ISOTECH SEMINAR 2014 Slide 1 Introducing the RBC

2. ISOTECH SEMINAR 2014 Slide 2 Using the RBC Two Models Manual Automatic Principle is the same

3. ISOTECH SEMINAR 2014 Slide 3 Why use an RBC? How can you trust a microK? How can you trust an AC Bridge? How can you trust a high accuracy thermometer?

4. ISOTECH SEMINAR 2014 Slide 4 Why use an RBC? The solution is the RBC

5. ISOTECH SEMINAR 2014 Slide 5 Ratio Measurement Bridges of this type make ratio measurements

6. ISOTECH SEMINAR 2014 Slide 6 The Requirement Historically for ratio bridges “by design” was accepted Today they need validation Requirement Linearity validation to <0.01ppm RBC is the only solution

7. ISOTECH SEMINAR 2014 Slide 7 Solutions Can’t use fixed resistors, why? Wilkins resistors (best available): Tolerance 0.05ppm (DC) / 1ppm (AC) 0.5ppm/°C 2ppm/year £1,200 RBC can generate ratios accurately

8. ISOTECH SEMINAR 2014 Slide 8 Making Resistance Ratios

9. ISOTECH SEMINAR 2014 Slide 9 Insensitivity of Ratio

10. ISOTECH SEMINAR 2014 Slide 10 The RBC

11. ISOTECH SEMINAR 2014 Slide 11 4-Wire Measurement on RBC

12. ISOTECH SEMINAR 2014 Slide 12 70 Ratios Available 4 base resistors 35 combinations 70 ratios (including complements)

13. ISOTECH SEMINAR 2014 Slide 13 Optimum Choice of Resistors 35 Values derived from 4 resistors Values chosen to: Cover typical operating resistance RBC100: 16.8Ωto 130Ω RBC400: 30Ω to 400Ω

14. ISOTECH SEMINAR 2014 Slide 14 Technical Challenges Making a zero-ohm common point Connecting resistors without the added resistance creating errors Keeping resistors constant during measurement period

15. ISOTECH SEMINAR 2014 Slide 15 Combining Networks Current sharing resistors Ensure current divide correctly Potential sharing resistors Average potentials

16. ISOTECH SEMINAR 2014 Slide 16

17. ISOTECH SEMINAR 2014 Slide 17 What’s New with the RBC-A Temperature controllable Much better uncertainty Automation Test of 8-16 hours Difficult to maintain concentration Now just 5 minutes operator time Massive reduction on cost per test

18. ISOTECH SEMINAR 2014 Slide 18 What’s Good about the RBC-A Unrivalled performance Only device capable of validating primary AC & DC bridges Automatic (BIG advantage) Can be temperature controlled Same case as Tinsley Wilkins resistor Never needs calibration

19. ISOTECH SEMINAR 2014 Slide 19 Concept developed by Rod White – at the NMI of New Zealand Patented in 1994 RBC Provenance

20. ISOTECH SEMINAR 2014 Slide 20 “A Method for Calibrating Resistance Thermometry Bridges” Rod White evaluated 38 Bridges, small but significant faults were found with 15% of those tested, but “like the walking wounded” they continued to provide a plausible reading. Trends in Temperature Calibration: Increasing Bridge Confidence

21. ISOTECH SEMINAR 2014 Slide 21 RBC-A – How to Use Connects via USB Controlled by Software Select Bridge Settings

22. ISOTECH SEMINAR 2014 Slide 22 RBC-A – How to Use Select Measurement Settings

23. ISOTECH SEMINAR 2014 Slide 23 RBC-A – How to Use Select the combinations

24. ISOTECH SEMINAR 2014 Slide 24 RBC-A – How to Use The software will set the combinations, read the data, produce a report and print a certificate Manual Model – includes software but the bridge readings and RBC setting has to be managed by hand