Comparative Analysis in Capacity Measurements
V. M. Ivancheva, R. T. Deliyski,K. S. Galabov,
B. P. Dzhudzhev, S. Z. Kachulkova
Abstract: In this paper comparative analysis in capacity measurements is accomplished. Multiple capacity readings are sampled trough RLC meters, Vin’s bridge as well as NI ELVIS II. ………….
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Key-Words: capacity, dissipation factor, AC bridges, conformance measures, Hellinger and Bray Curtis metrics.
1.Introduction
Measuring components of the complex impedance (real and imaginary part, modulus and phase) and the parameters of the circuits …
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2. Methodology
Bridge circuits are among the most commonly used method for capacity measurement. …..
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2.1. Methods for measuring parameters of a capacitor
The state of a linear circuit with a sine AC depends on the complex impedance …..
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2.2. Comparative metrics
When compare measurement readings, variety of metrics can be applied. ……
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Equations defining the metrics used in the analysis are as follow:
(1)
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where: BC is BrayCurtis distance ………….
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3. Experiments
Four different measurement tools were used to collect the data for processing. Every one of the tools measured ten times the applied true value. …………..
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The connection between the measuring instruments and the calibrator is shown in figure 1.
Fig, 1. Experimental set
3.1. Multifunction Calibrator CX 1651.
CX 1651 is used for calibration of measuring instruments for the next values: voltage, current, resistance, capacitance, ….
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Table 1
range / uncertainty of value [%] / max. frequency900 pF - 2.5 nF / 0.5 + 15 pF / 1000 Hz
2.5 nF - 10 nF / 0.5 + 5 pF / 1000 Hz
10 nF - 50 nF / 0.5 / 1000 Hz
50 nF – 250 nF / 0.5 / 1000 Hz
250 nF - 1μF / 0.5 / 500 Hz
1μF – 2.5μF / 1 / 300 Hz
2.5μF - 5μF / 1 / 300 Hz
5μF – 10μF / 1.5 / 300 Hz
10μF - 50μF / 2.0 / 300 Hz
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3.2. Metrological characteristics of measuring instruments.
In table 2 the metrological characteristics of the instruments used for measuring the parameters of the capacitor are given.
Table 2
№ по ред / Measuring instrument / Range / Accuracy for Capacitance / Selectable Test Frequency:1 / Escort ELC-131D / 1,000 pF to 10 mF / 0.7% Basic / 120Hz/1kHz
2 / LCR E7-8 / 0.01 pF to 100µF / n/a / 1000Hz
3 / NI ELVIS II / 50 pF to 500 pF
500 pF to 500 μF / 1% / 10 kHz
1 kHz
4 / Instrumentation module TK2941A by Feedback. / n/a / n/a / 300 to 1000Hz.
4. Results
The statistic gives us lots of tools to process measured data and represent every sample with only one point. …….
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Table 3. True measured values used
True value / 950pF / 2nF / 5nF / 90nF / 200nF / 500nF / 750nF / 1μF / 2μF / 3μF / 5μF / 7,5μF / 10μF / 20μF / 50μFEscort ELC-131D
Measured
average value / 0.960 / 2.013 / 5.011 / 89,986 / 200,2 / 500 / 750,86 / 1,001 / 1,999 / 3,012 / 5,028 / 7,551 / 10,061 / 20,05 / 47,531
LCR E7-8
Measured average value / n/a- / 1.800 / 4.80 / 89,7 / 199,9 / 499,3 / 749,8 / 1,004 / 2,018 / 3,042 / 5,04 / 7,558 / 10,7 / 20,88 / 49,92
NI ELVIS II
Measured average value / n/a / n/a / 5.08 / 90,58 / 201,84 / 503,73 / 756,62 / 1,01 / 2,02 / 3,05 / 5,09 / 7,68 / 10,29 / 20,84 / 50,8
Vine bridge
Measured average value / n/a / n/a / n/a / 90 / 200 / 500 / 750 / 1 / 1,99 / 2,99 / 4,99 / 7,403 / 9,9 / n/a / n/a
Table 3 above presents true and measured average values for the fourth measurement tools when 950 pF, 2 nF and 5 nF were applied. The results clearly show that …..
A bit more readable results are provided by Hellinger distance (Fig. 2). …..
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Fig. 2.Hellinger distance
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5. Conclusions
All methods proved that the most inaccurate measurement tool used in experiments are ………
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6. References
[1] H. K. Radev.Metrologiya i izmervatelna tehnika, tom 1,2,3, Sofiya, Softtreyd, 2010, ISBN 978-954-334-094-1
[2] B. I. Matrakov.Elektricheski izmervaniya, Sofiya, IPK pri TU, 1999
[3]
mathematica/guide/DistanceAndSimilarity
Measures.html, accessed on June 24th, 2013
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Acknowledgments
This paper presents the results obtained from the work of the project ……..
Authors:
Veselka Marinova Ivancheva,MSc in Electronics (1978), PhD in Electronics (2000), Assoc. prof. (2002) in the Department of Electrical Measurements, Faculty of Automatics, Technical University Sofia, Bulgaria. Scientific field and interests: Electrical Measurements, Measurement of Non-electrical Quantities. Workplace:Technical University-Sofia, Faculty of Automatics, Department of Electrical Measurements, Мailing address Sofia 1000, 8 Kliment Ohridski blvd, Web address:
e-mail address:
Radoslav Tsvetkov Deliyski.……………
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Krasimir Simeonov Galabov,…………
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Bozhidar Petkov Dzhudzhev……………
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Silviya ZaharievaKachulkova…………
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