A method for measuring low capacitance for tomography

Shao, Fuqun; Mong, QinGuo

doi:10.1063/1.1149883

Cited by 7 publications

(5 citation statements)

References 6 publications

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“…Single-shot high-voltage circuit for electrical capacitance tomography W T Smolik, J Kryszyn, B Radzik, M Stosio, P Wróblewski, D Wanta, Ł Dańko, T Olszewski and R Szabatin excitation from many electrodes and signal receiving at one electrode [16]; an implementation of a phase-sensitive demodulator using synchronous switching instead of analogue multiplication, which is simpler in realization [17]; and a digital demodulator based on fractional cycle data sampling, which improves the data acquisition speed [18]. Some investigators proposed an application of high-voltage (HV) excitation to increase the SNR [19,20]. The application of magnetic capacitance/voltage conversion of the signal in which a transformer is used to transform impedance was proposed in [19] as a method of eliminating stray capacitance influence on measurement.…”

Section: Measurement Science and Technologymentioning

confidence: 99%

“…Some investigators proposed an application of high-voltage (HV) excitation to increase the SNR [19,20]. The application of magnetic capacitance/voltage conversion of the signal in which a transformer is used to transform impedance was proposed in [19] as a method of eliminating stray capacitance influence on measurement.…”

Section: Measurement Science and Technologymentioning

confidence: 99%

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Single-shot high-voltage circuit for electrical capacitance tomography

Smolik

Kryszyn

Radzik

et al. 2016

Meas. Sci. Technol.

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A new method of capacitance measurement for electrical capacitance tomography is presented. A single-shot excitation is used to accelerate measurement. A high-voltage pulse and oversampling of received signal are applied to obtain an acceptable signal-to-noise ratio. The results of measurements of standard capacitors and mutual capacitance of electrodes in 16 electrode tomographic sensors are presented. The elaborated circuit is stray-immune. It can measure capacitance in a range from about 1 fF to 1 pF at one gain setting with good linearity and precision at the rate of 20 000 samples per second.

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Section: Measurement Science and Technologymentioning

confidence: 99%

Section: Measurement Science and Technologymentioning

confidence: 99%

Single-shot high-voltage circuit for electrical capacitance tomography

Smolik

Kryszyn

Radzik

et al. 2016

Meas. Sci. Technol.

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“…There are known measurement methods which involve a high excitation voltage, i.e. based on a single high-voltage excitation and a magnetic C/V converting method which is immune to the stray capacitances [16]. A detecting part of the circuit is separated from the excitation circuit with a toroidal transformer, which also transforms impedance.…”

Section: Introductionmentioning

confidence: 99%

Switchless charge-discharge circuit for electrical capacitance tomography

Kryszyn

Smolik

Radzik

et al. 2014

Meas. Sci. Technol.

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The main factor limiting the performance of electrical capacitance tomography (ECT) is an extremely low value of inter-electrode capacitances. The charge-discharge circuit is a well suited circuit for a small capacitance measurement due to its immunity to noise and stray capacitance, although it has a problem associated with a charge injected by the analogue switches, which results in a dc offset. This paper presents a new diode-based circuit for capacitance measurement in which a charge transfer method is realized without switches. The circuit was built and tested in one channel configuration with 16 multiplexed electrodes. The performance of the elaborated circuit and a comparison with a classic charge-discharge circuit are presented. The elaborated circuit can be used for sensors with inter-electrode capacitances not lower than 10 fF. The presented approach allows us to obtain a similar performance to the classic charge-discharge circuit, but has a simplified design. A lack of the need to synchronize the analogue switches in the transmitter and the receiver part of this circuit could be a desirable feature in the design of measurement systems integrated with electrodes.

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“…Low capacitance measurement is involved in many industrial applications, especially in the applications of electrical capacitance tomography [1][2][3][4][5] ͑ECT͒. For instance, the standing capacitances ͑empty sensor͒ of a 12-electrode ECT system are from 0.01 to 0.5 pF and the changes in capacitance when the sensor is filled with polystyrene beads is only from 5 to 80 fF.…”

Section: Introductionmentioning

confidence: 99%

A high voltage method for measuring low capacitance for tomography

Shao

Guo

2009

Review of Scientific Instruments

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Low capacitance measurement is involved in many industrial applications, especially in the applications of electrical capacitance tomography (ECT). Most of the low capacitance measurement circuits employ an ac-based method or a charge/discharge method because of high sensitivity, high resolution, and immunity to stray capacitance; and its excitation or charge voltage are not more than 20 V. When ECT techniques for large industrial equipment such as blast furnaces or grain barns are explored, the existing methods for measuring low capacitance have some limitations. This paper proposes a high excitation voltage ac-based method for measuring low capacitance to improve the resolution of measurement. The method uses a high excitation voltage of several hundred volts and a transformer ratio arms as the C/V transducer. Experimental results indicate that the new method has a resolution of 0.005 fF, a good stability (about 0.003 fF over 4 h) and linearity (0.9992).

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A method for measuring low capacitance for tomography

Abstract: A high precision method for measuring very small capacitance changes Rev.

Cited by 7 publications

References 6 publications

Single-shot high-voltage circuit for electrical capacitance tomography

Single-shot high-voltage circuit for electrical capacitance tomography

Switchless charge-discharge circuit for electrical capacitance tomography

A high voltage method for measuring low capacitance for tomography

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