MMU Repository of Academic Resources (Miyazaki Municipal University)
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Development of Optical Current Sensor System for Distribution Lines and Measurement of Harmonic Current in High Voltage Distribution Lines
Get PDFRecently, the fiber optical current sensors based on the Faraday effect have been developed and applied to power distribution systems. However, there are some requirements for putting the sensors on practical power distribution lines, that is, it is desired that they are of compact form and light weight, and also operate in high sensitivity and accuracy in a wide temperature range, etc. It is well known that garnets, especially bismuth-substituted rare-earth iron garnets (hereafter call as RIG), have the Verdet constants of higher sensitivity than other Faraday materials such as Bi12GeO20, while the constants of the sensitive RIG have a temperature dependency.
In this work, first, the same three sets of optical current sensor systems consisting of a RIG films were manufactured. Second, in room laboratory, the sensitivity and temperature dependency of each sensor system were examined by measuring the output voltages of the detecting unit corresponding to the currents flowed in 6kV three-phase power distribution lines. As a result, it was found that the deviation in the linearity of output voltages to applied currents of each sensor was within ±1.2% and these sensors had a high accuracy less than ±1.3% in a tempereture range from -20 to 80℃, and these values are satisfactory ones from the practical viewpoint. Moreover, as a field test, the three sets of sensor systems individually were set without ring core on the actual three-phase power distribution lines at hot-line conditions, the normal load line currents in the three-phase power distribution lines were measured for a long time by using these three set of sensor systems together with the conventional current transformers. As a result, it was found that the optical current sensor system used in this work had successfully good characterstics in practical use. Also, the harmonic current in high voltage distribution lines were measured with these optical current sensor systems, and they were analyzed by a computer.departmental bulletin pape
BASIC STUDY ON LASER-INDUCED DISCHARGE
Get PDFSince the observation of laser breakdown plasmas in gasses was reported for the first time 1963 and the possibility of the laser-induced lighting(LIL) was proposed by L. Ball et al. in 1974, as a basic study of the LIL, the laboratory-scale experiments of discharge induction have been performed with a long gap in the atmospheric air using a high energy laser. To realize the LIL, we need to clarify the mechanism of the discharge induction and the characteristics of the plasma produced by the laser.
So, we measured the electron density, the temperature and the neutral particle density in the plasma produced by the small CO2 laser by means of the laser Thomson scattering and the Rayleigh scattering method. Furthermore, we measured the 50% sparkover voltage for the plate-to-plate electrodes with a short gap and observed the discharge paths for the needle-to-needle electrodes using a CCD camera.
As a result, it was found that the existence of the oxygen molecules having the powerful electron affinity greatly influenced the discharge induction because the electron density in the plasma was decreased by the electron attachment to the oxygen molecules. For the neutral particle density, the thin air region expanded rapidly to the radial direction up to 20㎲ after firing the laser, and it expanded slowly after 20㎲. On the other hand, the neutral particle density near the axis of the plasma at the focal point was getting to recover gradually to the atmospheric level; the thin air shell was made. We confirmed that the discharge paths passed through the most thin air region compared with the spatio-temporal distribution of the neutral particle density.departmental bulletin pape
Autonomy in Language Learning: possible applications at Miyazaki Municipal University
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Comment on the Gender of Genus in the Nomenclature of Zoology and Botany. (1) Genera of Animals and Plants Ending -on.
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Comparison of the Influences of Calculation Error and the Preventive Measures on Two Methods to Discern Intersection
Get PDFTwo important kinds of calculation methods to discern intersection of two-dimensional line segments are theoretically and experimentally compared each other concerning the influence of calculation error: one is that using the position of the intersection of straight line, and the other is that using the mutual relation of position between one line segment and endpoints of another. The result shows that it is possible in the former that topological inconsistency is caused by calculation error when line segments approach each other, but little in the latter. Hence the latter seems to be superior in the measures against calculation error.departmental bulletin pape
A study of Adolescent Body Composition: the Implementation of Dual Energy Absorptiometry.
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Aspect of Dzongkha Language -Predication with Aktionsart Particles-
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