• Title/Summary/Keyword: Sensor installation error

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A Study on Comparison of the Characteristic Test of Discharge Water Flowmeters (Electromagnetic Flowmeter, Parshall Flume) (방류수 유량계(전자기유량계, 파샬플룸)의 특성평가 연구)

  • An, Yang-ki;Kim, Jee-young;Kim, Kum-hee;Jang, Hee-soo;Jung, Jung-pil;Choi, Jong-woo
    • The KSFM Journal of Fluid Machinery
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    • v.18 no.6
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    • pp.57-62
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    • 2015
  • The test of comparing liquid flow calibration system (approved by KOLAS) for accuracy and structure change test was performed in the test bed in order to evaluate the typical characteristics of the electromagnetic flow meters and parshall flume that are generally used in the water discharging facilities. The results of the accuracy comparing test with liquid flow calibration system showed the error of less than 2%. Pharshall plume got error up to -8.3% (low flow) from the flow rate test, but less than 4% from the accumulated flow test because of offset error at high flow rate and low flow rate. Evaluation of structual change test was tested with only parshall flume using structure and it consisted of installation angle (parshall flume and level sensor) and position change. Installation angle, water level sensor angle and position changing test for parshall flume had errors of 3.1%~-9.2%, 0.4%~-5.6% and 0.2%~1.3% respectively. Especially, the error showed the largest increase when the water level sensor measured the point of decreased flow by the structure change. Therefore, error factors (change of straight pipe length, installation of obstacle or effect of foreign substances on water level sensor) that can often occur in the field should be derived and the research for optimized installation method should be carried out continuously.

A Disk-type Capacitive Sensor for Five-dimensional Motion Measurements (5 차원 변위 측정용 원판형 정전용량 센서)

  • Ahn, Hyeong-Joon;Park, Jung-Ho;Um, Chang-Yong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.655-662
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    • 2007
  • This paper presents a disk-type capacitive sensor for simultaneous measurement of five-dimensional motions of a target. The sensor can be manufactured with a printed circuit board (PCB) such that the sensor can be integrated with its electronics in a single PCB board, whereby the manufacturing costs is considerably reduced. The sensor is optimally designed through an error analysis of possible mechanical errors. Furthermore, the sensor can correct the horizontal motion measurement errors due to the sensor installation tilting error. A proto-type PCB sensor, electronics and a test rig were built, and the effectiveness of the developed sensor was proved through experiments.

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Installation Error Calibration by Using Levenberg-Marquardt Method on a Cubic Parallel Manipulator (Levenberg-Marquardt 방법을 이용한 육면형 병렬기구의 설치 오차 보정)

  • 임승룡;임현규;최우천;송재복;홍대희
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.2
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    • pp.184-191
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    • 2003
  • A parallel manipulator has high stiffness and all the joint errors on the device are not accumulated at the end -effector unlike a serial manipulator. These are the reasons why the parallel manipulator has been widely used in many fields of industry. In the parallel manipulator, it is very important to predict the exact pose of the end-effector when we want to control the end-effector motion. Installation errors have to be determined in order to predict and control the actual position and pose of the end-effector. This paper presents an algorithm to find the whole 36 joint error components with joint clearance errors and measurement errors considered, when a link length measurement sensor is used and data more than 36 times are acquired for 36 different configurations. A simulation test using this algorithm is performed with a Matlab program which uses the Levenberg-Marquardt method that is known to be efficient for non-linear optimization.

A Comparison of Signal Processing Techniques in Optical Current Sensor for GIS

  • Kim, Young-Min;Park, Jung-Hwan;Jee, Seung-Wook;Lee, Kwang-Sik;Kim, Jung-Bae;Park, Won-Zoo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.20 no.9
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    • pp.103-109
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    • 2006
  • This research is contents about output characteristic of optic current sensor that use faraday effect. optic current sensor used in an experiment is consisted of three parts.(1) Source of light used laser diode of 1310[nm].(2) Sensor section manufactured circularly according to gas insulated switchgear. And $9/125[{\mu}m]$ standard single mode optical fiber for communication was installed winding 20 [turn] on sensor section core surroundings of diameter 31 [cm].(3) Electrical signal of PD(Photo detector) is collected using NI company's 16bit DAQ board via terminal block. Collected data analyzed by different three signal processing methods. NI company's $Labview^{TM}$ was used to signal processing software. As a result, In signal processing of optic current sensor, we could know that noise greatly more influences the error generation than fluctuation of light intensity. also, 1 class CT(current transformer) manufacture that have error rate less than 1[%] was available by removing these

SPATIAL AND TEMPORAL INFLUENCES ON SOIL MOISTURE ESTIMATION

  • Kim, Gwang-seob
    • Water Engineering Research
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    • v.3 no.1
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    • pp.31-44
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    • 2002
  • The effect of diurnal cycle, intermittent visit of observation satellite, sensor installation, partial coverage of remote sensing, heterogeneity of soil properties and precipitation to the soil moisture estimation error were analyzed to present the global sampling strategy of soil moisture. Three models, the theoretical soil moisture model, WGR model proposed Waymire of at. (1984) to generate rainfall, and Turning Band Method to generate two dimensional soil porosity, active soil depth and loss coefficient field were used to construct sufficient two-dimensional soil moisture data based on different scenarios. The sampling error is dominated by sampling interval and design scheme. The effect of heterogeneity of soil properties and rainfall to sampling error is smaller than that of temporal gap and spatial gap. Selecting a small sampling interval can dramatically reduce the sampling error generated by other factors such as heterogeneity of rainfall, soil properties, topography, and climatic conditions. If the annual mean of coverage portion is about 90%, the effect of partial coverage to sampling error can be disregarded. The water retention capacity of fields is very important in the sampling error. The smaller the water retention capacity of the field (small soil porosity and thin active soil depth), the greater the sampling error. These results indicate that the sampling error is very sensitive to water retention capacity. Block random installation gets more accurate data than random installation of soil moisture gages. The Walnut Gulch soil moisture data show that the diurnal variation of soil moisture causes sampling error between 1 and 4 % in daily estimation.

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Accuracy improvement of FBG temperature sensor system for usage in electric power systems (전력 시스템 보호를 위한 광섬유 격자 온도센서의 정밀도 개선)

  • Lee, Hyun-Wook;Lee, Jun-Ho;Song, Min-Ho
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2005.05a
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    • pp.421-425
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    • 2005
  • A distributed FBG temperature sensor system was constructed for the use in protection of electric power system. A F-P wavelength tunable filter is used converting temperature-induced wavelength variations to temporal peak locations. We used Gaussian line-fitted algorithm to alleviate the error caused by quantization and electrical noises. The experimental results showed much better accuracy than the raw peak-detection scheme.

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Effects of reflective index of fiber sensor coil end on current measurement (광CT 센서코일 끝단의 반사율이 전류측정에 미치는 영향)

  • Park, Hyoung-Jun;Kim, Hyun-Jin;Song, Min-Ho
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2008.05a
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    • pp.74-77
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    • 2008
  • We improved an efficiency of fiber-optic current transformer by using a metal-coated sensor coil. To reduce the linear birefringence, we used a length of spun fiber as sensor coil, and then used a flint glass fiber coil for comparison. To make the sensor coil in the reflection type, we used different reflection mirrors at the end of the sensor coil, such as a Faraday rotator mirror, a simple mirror, a metal-coated fiber end and a simple fiber end. From the experimental results, the linear error of current measurements were less than ${\sim}$ 0.2 % regardless of the mirror types. The metal-coated sensor was the most cost-effective considering the fabrication cost and the simple structure.

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Characteristics of Optical Current Sensors by Sensor Design

  • Kim, Young-Min;Park, Jung-Hwan;Lee, Kwang-Sik;Kim, Jung-Bae;Park, Won-Zoo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.4
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    • pp.80-87
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    • 2007
  • This paper will suggest that the 1 cross orthogonal loop type sensor improves on the orthogonal loop form sensor-head, which is available a calibration of the linear birefringence, when a fiber optic current sensor was composed. An output characteristics of the 1 cross orthogonal loop form, a general closed loop form, the orthogonal loop form are compared by the IEC(International Electrotechnical Commission) 60044-8 standard, and the state of polarization is compared with three forms. As a result, when the closed loop form was changed to the orthogonal loop form, retardation decreased 15.3[%]. When the closed loop form was changed to the 1 cross orthogonal loop type, the retardation decreased 33.8[%]. As a result of the Faraday Effect measurement, the 1 cross orthogonal loop form has the highest output characteristic and the lowest error ratio. It met the 0.5 class of the IEC 60044-8 standard. Thus, in application of the 1cross orthogonal loop form, the possibility to develop high reliability fiber optic current sensors that have a high output and stable error ratio rises is increased.

Distributed fiber-optic sensor network for the over temperature protection relay of electric power systems (전력설비 보호를 위한 온도계전기용 광섬유 분배센서)

  • Park, Hyoung-Jun;Lee, June-Ho;Song, Min-Ho
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2006.05a
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    • pp.86-90
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    • 2006
  • We prosed a distributed fiber-optic sensor system with 10 fiber Bragg gratings, for over temperature protection relay in power systems. We applied Gaussian line-fitting algorithm to compensate the distortion effects in the wavelength-scanned Farby-Perot filter demodulation scheme. Compared with the highest-peak-detection method, the proposed algorithm was proved to minimize the random errors of distorted PD profiles. From experimental results, the overall measurement error was within 1 % compared with the reference thermocouple and the linearity error was less than 0.37 %.

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A Study on Effects of Offset Error during Phase Angle Detection in Grid-tied Single-phase Inverters based on SRF-PLL (SRF-PLL을 이용한 계통연계형 단상 인버터의 전원 위상각 검출시 옵셋 오차 영향에 관한 연구)

  • Kwon, Young;Seong, Ui-Seok;Hwang, Seon-Hwan
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.10
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    • pp.73-82
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    • 2015
  • This paper proposes an ripple reduction algorithm and analyzes the effects of offset and scale errors generated by voltage sensor while measuring grid voltage in grid-tied single-phase inverters. Generally, the grid-connected inverter needs to detect the phase angle information by measuring grid voltage for synchronization, so that the single-phase inverter can be accurately driven based on estimated phase angle information. However, offset and scale errors are inevitably generated owing to the non-linear characteristics of voltage sensor and these errors affect that the phase angle includes 1st harmonic component under using SRF-PLL(Synchronous Reference Frame - Phase Locked Loop) system for detecting grid phase angle. Also, the performance of the overall system is degraded from the distorted phase angle including the specific harmonic component. As a result, in this paper, offset and scale error due to the voltage sensor in single-phase grid connected inverter under SRF-PLL is analyzed in detail and proportional resonant controller is used to reduce the ripples caused by the offset error. Especially, the integrator output of PI(Proportional Integral) controller in SRF-PLL is selected as an input signal of the proportional resonant controller. Simulation and experiment are performed to verify the effectiveness of the proposed algorithm.