Extension and Improvement of Capacitance and Induction Measurement Capabilities at NMISA. Name: Michael Khoza Date:

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1 Extension and Improvement of Capacitance and Induction Measurement Capabilities at NMISA Name: Michael Khoza Date: NMISA 2013

2 Table of contents Project overview Instrumentations Traceability Chart Methodology Uncertainty Contributors and Evaluation New Measurement Capabilities: Inductance and Capacitance Conclusion NMISA 2013

3 Project overview Project was initiated by NMISA impedance laboratory aimed to address the shortfall of impedance measurement services required by industry. Industry required traceability of capacitance and inductance measurements at test frequency from 50 Hz to 1 MHz, and uncertainty of measurements better than 400 ppm. Laboratory offered capacitance and inductance traceable measurements up to 200 khz, and uncertainty of measurements better of 400 ppm. LCR Meter operating at a frequency from 20 Hz to 2 MHz was acquired. Measurements were performed and new uncertainty of measurements calculated, frequency measuring range extended to 1 MHz.

4 Instrumentations Agilent E4980A 20 Hz 2 MHz Precision LCR meter & Quadtech Hz 200 khz RLC Digibridge AH2700A 50 Hz 20 khz Ultra Capacitance Bridge, AH2500A 1 khz Ultra Capacitance Bridge & 1 pf 100 pf Andeen Hagerling standard capacitors 1 nf 1 µf General Radio 1409 series standard capacitors 100 µh 10 H General Radio 1482 series standard Inductors 4 Terminal 1 pf 10 µf series standard capacitors

5 Traceability Chart National Metrology Institute: Physikalish Technische Bundesa nstalt, inductance and capacitance National Metrology Institute: NMISA Natio nal capacitance and inductance Measurement Standards National Metrology Institute: Bureau International Des Poids ET Measures, capacitance Imported accuracy and traceability transferred to internal laboratory standards Research institutes and a ccredited facilities Manufacturing industries, customers

6 Methodology Substitution method was used, and the national standard used as calibrated reference standard, laboratory standard as UUT (unit under test) New LCR meter measured both the national and laboratory standards Drift of the national standard determined and correction applied. Equation (1) used for capacitance and (2) used for inductance (1) Where: C x = Calculated value value of the UUT (unit under test) LCR cx = Measured value of the UUT LCR cs = Measured value of the reference standard Cs (certified) = Certified corrected value of the reference standard

7 Methodology: Cont (2) I x = Calculated inductance value of the UUT (unit under test) LCR Ix = Measured inductance value of the UUT LCR Ls = Measured inductance value of the reference standard I s (CERTIFIED) = Corrected certified value of the reference standard

8 Uncertainty Contributors and evaluation RLC Meter Resolution Temperature coefficient of the laboratory standards UoM of the laboratory standards RLC Meter Stability RL C Meter accuracy Voltage coefficient of the laboratory standards Drift of the laboratory standards ESDM of the mean value Expanded UoM of the measurand

9 Uncertainty Contributors and evaluation: cont Source of Uncertainty Estimated Uncertainty Type of Distribution Divisor Factor Standard Uncertainty Reliability Degree of Freedom Calibration Uncertainty of Measurement of the Laboratory Standards A Normal 2 = A/2 100 % ESDM of the Mean Value B Normal 1 = B/1 100 % Temperature coefficient of the Laboratory Standards C Rectangular 3 = C/ % Voltage coefficient of the laboratory standards D Rectangular 3 = D/ % Drift of the laboratory standards E Rectangular 3 = E/ % RCL/ LCR Meter stability F Rectangular 3 = F/ % RCL/ LCR Meter resolution RCL/ LCR Meter accuracy G Rectangular 3 = G/ % H Rectangular 3 = H/ % Combined standard uncertainty = ( A/2^2+. H/ 3^2) Expanded uncertainty =2* Combined standard uncertainty

10 New Measurement Capabilities: Inductance Inducatnce measurement capabilities Inductance value Test Frequency 100 Hz 1 khz 100 µh X 300 ppm 1 mh X 70 ppm 10 mh X 60 ppm 100 mh X 60 ppm 1 H 80 ppm 80 ppm 10 H 80 ppm 80 ppm Note: X means not accredited

11 New Measurement Capabilities: Capacitance Capacitance measurement capabilities Capacitance value Test Frequency 1 khz 10 khz 100 khz 1 MHz 1 pf 0,4 ppm 30 ppm 300 ppm 300 ppm 10 pf 0,4 ppm 30 ppm 300 ppm 700 ppm 100 pf 0,4 ppm 30 ppm 300 ppm 600 ppm 1 nf 2 ppm 30 ppm 300 ppm 600 ppm 10 nf 2 ppm 90 ppm 300 ppm 700 ppm 100 nf 3 ppm 300 ppm 300 ppm 2000 ppm 1 µf 20 ppm 400 ppm 600 ppm X 10 µf 100 ppm 600 ppm X X Note: X means not accredited

12 Conclusion NMISA Impedance laboratory sucessfully extended the capacitance and frequency range from 1 pf to 10 µf at 200 khz to 1 MHz The capacitance measurement capabilities improved from 400 pppm to 0,4 ppm. The inductance measurement range (traceable) remained unchanged from 100 µh to 10 H at 100 Hz and 1 khz, and the measurement capabilities improved from 400 ppm to 60 ppm.

13 THANK YOU