• Title/Summary/Keyword: Capacitive Detector

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Small Capacitance Measuring Circuit For Capacitive Sensors

  • Rerkratn, Apinai;Lertpakdee, Thanakorn;Chitsakul, Kitiphol;Sangworasil, Manas
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.483-486
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    • 2003
  • This paper presents a small capacitance measuring circuit for capacitive sensors. The proposed circuit consists of sinewave generator, detector and demodulator. Results of experiments are shown that the circuit can be able to measure small capacitance exiting in a capacitive sensor filled with a vegetable oil. The sensitivity of the circuit is from 0.4V/pF to 4V/pF and the resolution is from 0.0025 pF to 0.00025 pF.

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Capacitive Parameter Estimation of Passive Telemetry RF Sensor System Using RLS Algorithm (RLS 알고리즘을 이용한 원격 RF 센서 시스템의 정전용량 파라메타 추정)

  • Kim, Kyung-Yup;Lee, John-Tark
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.5
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    • pp.858-865
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    • 2008
  • In this paper, Capacitive Telemetry RF Sensor System using Recursive Least Square (RLS) algorithm was proposed. General Telemetry RF Sensor System means that it should be "wireless", "implantable" and "batterless". Conventional Telemetry RF Sensor System adopts Integrated Circuit type, but there are many defects like complexity of structure and the limitation of large power consumption in some cases. In order to overcome these disadvantages, Telemetry RF Sensor System based on inductive coupling principle was proposed in this paper. Proposed Telemetry RF Sensor System is very simple because it consists of R, L and C and measures the changes of environment like pressure and humidity in the type of capacitive value. This system adopted RLS algorithm for estimation of this capacitive parameter. For the purpose of applying RLS algorithm, proposed system was mathematically modelled with phasor method and was quasi-linearized. As two parameters such as phase and amplitude of output voltage for estimation were needed, Phase Difference Detector and Amplitude Detector were proposed respectively which were implemented using TMS320C2812 made by Texas Instrument. Finally, It is verified that the capacitance of proposed telemetry RF Sensor System using RLS algorithm can be estimated efficiently under noisy environment.

Implementation of Passive Telemetry RF Sensor System Using Unscented Kalman Filter Algorithm (Unscented Kalman Filter를 이용한 원격 RF 센서 시스템 구현)

  • Kim, Kyung-Yup;Lee, John-Tark
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.10
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    • pp.1861-1868
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    • 2008
  • In this paper, Passive Telemerty RF Sensor System using Unscented Kalman Filter algorithm(UKF) is proposed. General Passive Telemerty RF Sensor System means that it should be "wireless", "implantable" and "batterless". Conventional Passive Telemerty RF Sensor System adopts Integrated Circuit type, but there are defects like complexity of structure and limit of large power consumption in some cases. In order to overcome these kinds of faults, Passive Telemetry RF Sensor System based on inductive coupling principle is proposed in this paper. Because passive components R, L, C have stray parameters in the range of high frequency such as about 200[KHz] used in this paper, Passive Telemetry RF Sensor System considering stray parameters has to be derived for accurate model identification. Proposed Passive Telemetry RF Sensor System is simple because it consists of R, L and C and measures the change of environment like pressure and humidity in the type of capacitive value. This system adopted UKF algorithm for estimation of this capacitive parameter included in nonlinear system like Passive Telemetry RF Sensor System. For the purpose of obtaining learning data pairs for UKF Algorithm, Phase Difference Detector and Amplitude Detector are proposed respectively which make it possible to get amplitude and phase between input and output voltage. Finally, it is verified that capacitive parameter of proposed Passive Telemetry RF Sensor System using UKF algorithm can be estimated in noisy environment efficiently.

Measurement of Ultrasonic Nonlinearity Parameter of Fused Silica and Al2024-T4 (Fused Silica와 Al2024-T4의 비선형 파라미터 측정)

  • Kang, To;Lee, Taekgyu;Song, Sung-Jin;Kim, Hak-Joon
    • Journal of the Korean Society for Nondestructive Testing
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    • v.33 no.1
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    • pp.14-19
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    • 2013
  • Nonlinearity parameter is an inherent property of materials measuring fundamental acoustic amplitude($A_1$) and second harmonic amplitude($A_2$). However, measurement of $A_1$ and $A_2$ has complex calibration procedure, many researchers prefer to measure relative nonlinearity parameter rather than absolute nonlinearity parameter. But, relative nonlinearity parameter is only detect materials degradation with various degradation samples, it is limited application in determining third order elastic constants of materials. Therefore, in this study, the piezoelectric detection method is adopted to measure absolute nonlinearity parameter due to experimental simplicity compare to capacitive detector. Linearity of measurement system is verified by $A_1^2vsA_2$ plot, and we measured ultrasonic nonlinearity parameters of fused silica and Al2024-T4.

On-Line Insulation Diagnosis Techniques for Stator Winding of Rotating Machines (회전기 고정자 권선에서의 운전 중 절연열화 진단기법)

  • 윤대희;황돈하;신병철;김용주;이광식
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2000.11a
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    • pp.89-93
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    • 2000
  • Recently many research activities on the diagnosis of stator winding insulation of large rotating machines have been reported. Capacitive couplers are widely used as sensors for on-line partial discharge (PD) measurement of high voltage rotating machines. This paper presents laboratory test to compare Stator Slot Coupler (SSC), Resistance Temperature Detector (RTD), 80 [pF] coupler and 500 [pF] coupler for on-line PD measurement of rotating machines. And a novel on-line monitoring system for an insulation diagnosis is proposed.

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Air detector using the change of dielectric constant for medical applications (의료분야 응용을 위한 유전상수 변화를 이용한 공기감지 장치)

  • Kim, Kyung-Hwa;Shim, Joon-Hwan
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.6
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    • pp.864-870
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    • 2010
  • Air embolism can be a lethal complication of surgical procedures during which venous pressure at the site of surgery is sub-atmospheric or air is forced under pressure into a body cavity. To solve the problem, we developed the air detector using relative dielectric constant change, which is expected to be used broadly in industrial circles. We designed air detection system with air control equipment, detection circuit and LabVIEW system for air sensing. In experiments with a mock system, the proposed system showed a signal difference depending on the amount of air in the Tygon tube of the mock system.

Analysis of Insulation Condition in High Voltage Motor Model Coils (고압전동기 모델 코일의 절연상태 분석)

  • Kim, Hee-Dong;Kong, Tae-Sik;Kim, Byeong-Rae
    • Proceedings of the KIEE Conference
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    • 2003.07c
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    • pp.1612-1614
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    • 2003
  • 80pF capacitive couplers were connected to six 6.6kV motor model coil terminals. The voltage applied to the coils were 3.81kv, 4.76 kV and 6.6kV, respectively. These stator coils have various types of artificial insulation defects such as large voids, semi-conductive coating damage and strand insulation fault. Digital PD detector(PDD) and turbine generator analyzer(TGA) were used to measure PD activity. TGA summarizes each plot with two quantities such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). The PD levels in PD were measured with a conventional digital PD detector. Most of the defect mechanism of large motor stator winding can be associated with PD patterns such as internal and slot discharges. PD patterns coincide with PDD and TGA. These instruments have an input bandwidth of 40-400kHz and 0.1-350MHz. Surge testing detects faults in inter-turn winding of high voltage motor model coils.

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Design of Low Noise Readout Circuit for 2-D Capacitive Microbolometer FPAs (정전용량 방식의 이차원 마이크로볼로미터 FPA를 위한 저잡음 신호취득 회로 설계)

  • Kim, Jong Eun;Woo, Doo Hyung
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.10
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    • pp.80-86
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    • 2014
  • A low-noise readout circuit is studied for 2-D capacitive microbolometer focal plane arrays (FPAs). In spite of the merits of the integration method, a simple and effective pixelwise readout circuit without integration is used for input circuit because of a small pixel size and narrow noise bandwidth. To reduce the power consumption and the kT/C noise, which is the dominant noise of the capacitive microbolometer FPAs with small capacitance, a new correlated double sampling (CDS) is used for columnwise circuit. The proposed circuit has been designed using a $0.35-{\mu}m$ 2-poly 4-metal CMOS process for a microbolometer array with a pixel size of $50{\mu}m{\times}50{\mu}m$. The proposed circuit effectively reduces the kT/C noise and the other low-frequency noise of microbolometer, and the noise characteristics of the fabricated chip have been verified by measurements. The rms noise voltage of the proposed circuit is reduced from 30 % to 55 % compared to that of the simple readout input circuit, and the noise equivalent temperature difference (NETD) of the proposed circuit is very low value of 21.5 mK.

Development of A Capacitive Sensor for The Diagnosis of Electrical Insulating Oil (변압기 절연유 검진용 전기용량 센서 개발)

  • Kim, Han-Jun;Kang, Jeon-Hong;Kim, Ju-Han;Han, Sang-Ok
    • Proceedings of the KIEE Conference
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    • 2004.07c
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    • pp.1848-1850
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    • 2004
  • 변압기에 사용되는 절연유의 열화정도를 변압기의 운전정지 없이 실시간으로 측정할 수 있는 전기용량을 이용한 센서를 개발하였다. 개발된 전기용량형 센서는 3-전극형의 구조와 변압기에 센서의 외부상자가 접지 될 때 2중의 정전차폐가 되도록 하여 외부로부터의 잡음에 영향을 받지 않도록 하였다. 또한 변압기에서 절연유의 온도변화에 따른 유전율 변화를 보상하기위하여 기준용 센서와 측정용 센서를 한개의 변압기에 장착함으로 온도보상이 되도록 하였다. 제작된 센서는 변압기에서 절연유의 사용기간에 따른 유전율의 변화를 정확히 측정하였으며, 절연유의 체적저항의 변화도 감지 할 수가 있다. 따라서 센서에서 출력되는 신호를 phase sensitive detector를 사용하여 유전율의 변화로 혹은 체적저항의 변화로도 나타내 보일 수가 있다.

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Partial Discharge Properties of High Voltage Motor Stator Insulation using Partial Discharge Analyzer (PDA를 이용한 고압전동기 고정자 권선에서 부분방전 특성)

  • Kim, Hee-Dong;Lee, Sang-Kil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2001.05c
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    • pp.225-228
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    • 2001
  • Partial discharge(PD) testing for different capacitive couplers was performed on a 6.6kV, 448kW pulverizer motor. The motor has been in service for twenty years. PD tests were measured using digital partial discharge detector(DPDD) and partial discharge analyzer(PDA), respectively. PDA is used to in the motor stator insulation, which three 80pF or three 500pF epoxy-mica couplers were installed, one per phase. The 500pF couplers did detect more normalized quantity number(NQN) than the 80pF couplers. DPDD and PDA showed that PD and NQN magnitudes increased with increase of ac voltage. Internal discharge was discovered in the motor stator insulation. DPDD and PDA test results are in accordance with the pattern and magnitude of PD.

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