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Yuichi Maekawa Akio Yamaguchi Makoto Hara Yasuo Sekii 《Electrical Engineering in Japan》1994,114(8):1-12
This paper describes the development of dc XLPE cable. Through a series of material investigations, an XLPE compound containing highly purified special filler was developed. To check the dc insulation performance of the cable insulated with this new material, a prototype cable with 9 mm insulation thickness was manufactured. It was confirmed that the performance of the prototype cable was excellent. Based on the study of the prototype cable, a 250-kV dc cable with 20 mm insulation thickness was designed and manufactured. Through a series of voltage tests, excellent dc insulation performance of the developed cable was verified. 相似文献
2.
Ginzo Katsuta Atsushi Toya Takeshi Endoh Hiroshi Suzuki Yasuo Sekii 《Electrical Engineering in Japan》1992,112(7):77-91
A new method was used to measure the characteristics of partial discharge (PD) for an active 9.5-km long-distance 275-kV XLPE cable line with insulating joints. It was found that the detection of PD and the calibration of detection sensitivity were carried out safely and easily. The proposed method includes:
- 1 detection of PDs and injection of calibration pulses using two pairs of metal electrodes placed on PVC jackets with anti-corrosion layers separated by a joint sleeve sectionalizing insulator;
- 2 measurement of detection sensitivity with distance using calibration pulses injected from an adjacent insulating joint;
- 3 detection of PDs with a high S/N ratio measured at a frequency corresponding to the lowest noise level; and
- 4 usage of rf cores attached at cross-bonding leads and wires for sheath current limiters to reduce the crosstalk of signal and noise through these lines at insulating joints.
3.
Hiroaki Kawasumi Hiroshi Sekii Nobuyoshi Enomoto Hajime Ohata Akio Okazaki 《Electrical Engineering in Japan》1997,119(1):62-73
This paper describes a method of detecting intruders by video image processing. There are some studies on detecting intruders in video image by analyzing difference-binary images and motion vectors. Because of the use of simple features such as size and motion vectors of changing regions, these methods are not fully able to reduce erroneous detection caused by other factors, such as small animals, swaying of trees, and changes in brightness. We propose a method of detecting intruders by time-series data on the projection pattern of the silhouette. In this method, changing regions in video images are extracted by the interframe differential technique and are transformed into projection patterns. Evaluation scores (a measure of similarity to a human silhouette) are calculated by flexible matching between observed patterns and the standard pattern. Discrimination processing is carried out in terms of a time-series score by tracking a target of each video frame. We have made experiments with a prototype and confirmed the effectiveness of this method. © 1997 Scripta Technica, Inc. Electr Eng Jpn 119(1): 62–73, 1997 相似文献
4.
Watanabe Kiyoshi Yagyu Hideki Sekii Yasuo Marumo Moritada 《Power Delivery, IEEE Transactions on》1986,1(1):27-33
With a view to develop a new water tree suppressive XLPE cable, the authors have investigated the effect of introducing polar groups into crosslinked polyethylene (XLPE) dielectrics. An aliphatic carboxylic acid derivative was found to be the best additive as a water tree suppressor. New cables insulated with XLPE dielectrics containing this aliphatic carboxylic acid derivative were developed. It was confirmed that the cables, having the same physical and electrical properties as those of conventional XLPE cables, showed an excellent water tree suppressive effect and long term performance. 相似文献
5.
Ogata S. Sekii H. Maeda T. Goto H. Yamashita T. Imanaka K. 《Photonics Technology Letters, IEEE》1989,1(11):354-355
A microcollimated laser diode (MCLD) utilizing a 1-mm short focal length, φ0.5-mm small diameter micro Fresnel lens (MFL) as the collimating lens is discussed. The MCLD is assembled with a 780-nm quantum-well laser diode dice and an MFL in the smallest commercially available laser package. The radiated laser beam from the MCLD has a power of higher than 2 mW at 50 mA driving current, a φ2 mm beam diameter with a nearly Gaussian intensity profile, and a low wavefront aberration of less than λ/14 (RMS value) measured at a 1-m distance 相似文献
6.
A black surface was created using electrostatic flocking with polyacrylonitrile (PAN) carbon flock fibers. Reflectance of diffused reflection for ultraviolet, visible, and near-infrared rays was measured using the created flocked surfaces. The resultant surface exhibits extremely low reflectance values. Furthermore, the authors measured thermal emissivity of carbon-fiber flocked surfaces. A sample used for emissivity measurements was fabricated by pasting two pieces of flocked surface samples together, into which a heater and a thermocouple had been embedded. Using a space chamber of 1,050 mm diameter and 1,206 mm depth, emissivity measurements were carried out using calorimetry. The authors obtained 0.98 as the highest thermal emissivity of the flocked surface, demonstrating that the surface emissivity is almost equivalent to the value of a black body. Results of both measurements were discussed. 相似文献
7.
Katsuta G. Toya A. Muraoka K. Endoh T. Sekii Y. Ikeda C. 《Power Delivery, IEEE Transactions on》1992,7(3):1068-1079
Deterioration in the insulation performance of extra-high voltage XLPE (cross-linked polyethylene) cables is believed to be attributable to the deterioration caused by partial discharges. After using an XLPE cable to investigate the behavior of partial discharges under various adverse conditions, the authors succeeded in developing a highly sensitive novel method of measuring partial discharge in XLPE cable lines. Partial discharges in a 275 kV XLPE cable live line have been measured using this method. As a result, a detection sensitivity of 1 pC has been achieved 相似文献
8.
Katsuichi Ohata Ginzo Katsuta Zensuke Iwata Yoshio Maruyama Yasuo Sekii Mamoru Kanaoka 《Electrical Engineering in Japan》1993,113(5):59-70
To study the long-term characteristics of XLPE cables installed in free air and in water, aging tests were conducted under various testing conditions using XLPE cables with both 3.5 mm and 6 mm insulation. From the Weibull plots of lifetime distribution under the voltage stress EL as the minimum breakdown strength, the minimum value of time to breakdown tL under the constant voltage was estimated. The results of accelerated aging tests of XLPE cables installed in free air demonstrated that the V-t characteristics of XLPE cables could not be described by the conventional inverse power law (t ∝ V−n) with a single constant life exponent n. Based on the microscopic observation of a sliced insulation removed from XLPE cables, it was concluded that bow-tie trees with longer tree length observed in cables tested in water were caused by the moisture from outside, whereas the trees in cables tested in free air were caused by the residual moisture originally existing in the insulation. The breakdown strength of the aged cables tested in water increases through cable drying. However, it does not recover to the original values. 相似文献
9.
Ken Hirota Yasukuni Kanemitu Norihisa Kamada Yasuo Sekii 《Electrical Engineering in Japan》2001,135(3):1-7
In conjunction with previous experiments studying the effect of decomposition products of dicumyl peroxide (DCP) and antioxidants (AOs) in cross‐linked polyethylene (XLPE) insulation on electrical tree generation, the authors conducted experiments investigating tree inhibition by phenolic AOs. The experiments were conducted using XLPE slabs containing four different phenolic AOs. Among the specimens containing these AOs, the specimen containing 4,4é‐thio‐bis(3‐methyl‐6‐tert‐butylphenol) was found to show the highest tree inception voltage. To examine the reasons for the significant increase in tree inception voltage in this specimen, further experiments were carried out on XLPE specimens containing both phenolic AO and a sulfur‐containing AO. The results demonstrated that the tree inception voltages of specimens containing both phenolic AO and sulfur‐containing AO were higher than those of the specimens containing only one of these two types of AOs. The roles of antioxidants in XLPE dielectrics are discussed with reference to the mechanisms of autoxidation of polymeric materials. The great increase in the tree inception voltage of XLPE specimens containing 4,4é‐thio‐bis(3‐methyl‐6‐tert‐butylphenol) appears to be due to a synergistic effect between the phenolic AO and the sulfur‐containing AO. © 2001 Scripta Technica, Electr Eng Jpn, 135(3): 1–7, 2001 相似文献
10.
Charge generation in cross-linked polyethylene (XLPE) and ethylene propylene rubber (EPR) under dc stress are influenced strongly by inclusions. The inclusions influencing charge generation are cross-linking byproducts, antioxidants, and moisture. These inclusions particularly influence the generation of negative heterocharges observed near positive electrodes, which produce high electric stress regions in XLPE cable insulation under dc voltage. Because a high electric field might cause dielectric breakdown of high-voltage equipment, it is important to minimize negative heterocharge accumulation. Consequently, the authors performed experiments to clarify the negative heterocharge generation mechanism in XLPE and EPR. The authors first studied the influence of cross-linking byproduct and moisture on negative heterocharge generation to clarify the mechanism. The authors next performed experiments to elucidate the effect of antioxidants on heterocharge generation, which revealed that the negative heterocharge is generated in XLPE insulation containing sulfur-containing phenolic antioxidant, or sulfur-type antioxidant. This heterocharge is presumed to be created by the combined effect of the antioxidant and acetophenone. Furthermore, the authors studied the dissipation of negative heterocharges in XLPE and EPR, clarifying that the dissipation of negative heterocharges in EPR is much faster than that in XLPE. This paper presents results of these studies. 相似文献
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