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157 results on '"Sakoda, Tatsuya"'

8. Short-Time Fabrication of Degraded Surface on Silicone Rubber Used for Insulators

Author

Khaing, May Thin, Yoshimura, Kosei, Miyake, Takuma, Sakoda, Tatsuya, Goto, Shigehiko, Anjiki, Tomikazu, Chiba, Tomoki, and Kasuga, Yasunori

Abstract

Silicone rubber (SiR) insulators are degraded due to multiple stresses. To develop a degradation diagnostic technique, a lot of aged insulators are required. However, collecting a lot of several decades of used SiR insulators is difficult. Therefore, it is desired to fabricate the degraded SiR surface whose characteristics are similar to those of degraded SiR insulators in outdoor. To grasp the characteristics of the degraded SiR surface, we first investigated the characteristics of aged SiR insulators. Foreign matters on aged SiR specimens made the contact angle larger, and Si–O, Si–CH3, C–H, and O–H bonds decreased. Next, to fabricate the artificially degraded SiR surface, we proposed a 24 h—fabrication—cycle, which consists of a red clay adhesion process, an ultraviolet (UV) irradiation process, a surface heating process, a heat radiation process, and a surface cleaning process. We evaluated the effects of UV irradiation and surface heating, and then, it was found that a combination of UV irradiation for breaking molecular structure and surface heating for promoting low molecular weight (LMW) dispersion played an important role in adhering red clay to SiR. The contact angle and the chemical structure on the artificially degraded SiR surface, which was fabricated by UV irradiation for 6 h and surface heating at 20 °C or 40 °C, were similar to those of a SiR specimen aged ten years with the hydrophobicity of hydrophobicity class (HC) 2.

Published
2024
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19. Measurement of low-frequency ultrasonic wave in water using an acoustic fiber sensor

Author

Sakoda, Tatsuya and Sonoda, Yoshito

Subjects
Ultrasonic waves -- Measurement, Diffraction -- Analysis, Water -- Acoustic properties, Business, Electronics, Electronics and electrical industries
Abstract

Measurement of low-frequency ultrasonic wave in water is examined using a step index fiber operating as a detection sensor, in order to characterize the acoustic fiber sensor as a basic study. The results show that characteristics of detected signals agree with the theoretical prediction based on Fraunhofer diffraction.

Published
2006

21. Evaluation of insulation performance of polymeric surface using a novel separation technique of leakage current

Author

Otsubo, Masahisa, Hashiguchi, Takuhei, Honda, Chikahisa, Takenouchi, Osamu, Sakoda, Tatsuya, and Hashimoto, Yousuke

Subjects
Business, Electronics, Electronics and electrical industries
Abstract

This paper describes a novel method to separate the leakage current, obtained in polymeric materials during a salt fog aging test, into three components of conductive current, corona discharge current and dry band arc discharge current. First, we investigated that the relationship between optical emissions due to discharges and a leakage current. Based on experimentally defined discharge types, the separation of the leakage current was carried out. Finally, the polymer surface was analyzed using an electron spectroscopy for chemical analysis (ESCA), and the change in the polymeric constituents was evaluated. The results showed that the cumulative charges due to the dry band arc discharge and the corona discharge to the total charge were about 20 and 10%, respectively. It was also found that a high temperature vulcanized (HTV) silicone rubber could retain its insulation performance better than a room temperature vulcanized (RTV). Index Terms--Insulation, polymer insulators, leakage current, conductive current, corona discharge, dry band arc current, ESCA, HTV, RTV.

Published
2003

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