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Dive into the research topics where Nobuo Takatsu is active.

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Featured researches published by Nobuo Takatsu.


holm conference on electrical contacts | 2009

Melting and Discharge Phenomena of Breaking Ag Contacts Using a Precisely Controlled Piezoelectric Actuator

Noboru Wakatsuki; Nobuo Takatsu; Toshiteru Maeda; Takayuki Kudou

Using a laminated ceramic piezoelectric actuator for a very slow (4 m/s) precisely controlled make/break operation, contact voltage Vc and contact current Ic, residue of melt surface and discharge for breaking hinge relays with Ag contacting electrodes are measured. To control mechanical conditions, the movable electrode had a finely shaped convex surface (curvature radius: 0.5 mm) and a flat fixed electrode. Make/break operation was attempted only once due to transformation of contact surface. Then, Vc and Ic were measured at 1.5 to 25 V and 0.1 to 5 A. Fusion spots and residue of electric discharge on the contact surface were quantitatively measured using a laser microscope. Even when Vc and Ic were larger than the minimum arc voltage and minimum arc current, respectively, a continuous arc discharge occasionally did not occur. For the case of Vc=25 V and Ic=1 A, electric discharge was spontaneously suppressed to less than 100 s. The displacement of the movable electrode was estimated to be several nanometers for the discharging time interval. The residues of discharge were multiple damaged spots in the range of 100 m in radius, which had a black and/or white rectangular convex and concave shape.


holm conference on electrical contacts | 2013

Equivalent Circuit Analysis for Transient Phenomena from Elastic Contact to Breaking Contact through Metal Melting

Takayuki Kudou; Noboru Wakatsuki; Nobuo Takatsu; Daisuke Hara

This paper explores the proposal of equivalent circuits of electric breaking contacts to analyze the transient phenomena from elastic metal contact to rupture. The time dependency of elastic contact resistance is derived from the actual measurement values with the low current condition. The equivalent circuit for the phenomena is divided into the three stages: the first stage from the energizing to the softening voltage Us, the second stage from Us to the beginning of the latent heat, and the third stage from the start of the latent heat to the melting at the melting voltage Um. The accumulation of Joule heat at the contacts is shown with the capacitor in the circuits. The analytical result was able to qualitatively explain the complicated contact transient response characteristic of the Au crossing 1.0 mm φ rod experiment with source voltage 25 V, load current 2.5 A. Experimental results are compared with the fusion phenomena of conventional current fuse.


holm conference on electrical contacts | 2010

Two Melting Phenomena in Breaking Ag Contacts Decided by Energizing Electric Circuit

Noboru Wakatsuki; Masahiro Oikawa; Takayuki Kudo; Nobuo Takatsu


電子情報通信学会技術研究報告. EMD, 機構デバイス | 2014

Finite element analysis of contacting cross-rod electrodes : Static Analysis of Mechanical contact, Joule heat, and Lorenz force (Electromechanical Devices : 国際セッション IS-EMD2014)

Masaki Ishigaki; Noboru Wakatsuki; Nobuo Takatsu


holm conference on electrical contacts | 2011

Transient Phenomena from Melting to Electric Discharge during Making and Breaking Operations of Electric Contacts

Takayuki Kudo; Noboru Wakatsuki; Nobuo Takatsu


IEICE technical report. EMD | 2010

Measurement of Breaking Phenomena of Ag and Au Crossbar Electric Contacts Depending on Contacting Spots

Takayuki Kudo; Noboru Wakatsuki; Nobuo Takatsu


電子情報通信学会技術研究報告. EMD, 機構デバイス | 2009

Analysis of electric contacts using an electric conductive cluster and an electric field effect cluster

Noboru Wakatsuki; Masahiro Oikawa; Takayuki Kudo; Nobuo Takatsu


電子情報通信学会技術研究報告. EMD, 機構デバイス | 2009

Examination of cluster model of arc ignition at electric contacts

Takayuki Kudo; Noboru Wakatsuki; Masahiro Oikawa; Nobuo Takatsu


電子情報通信学会技術研究報告. EMD, 機構デバイス | 2009

Examination of Cluster Model for Metal Melting of Electric Contacts

Masahiro Oikawa; Takayuki Kudo; Nobuo Takatsu; Noboru Wakatsuki


IEICE Transactions on Electronics | 2009

Analytical Model of Melting Phenomena for Breaking Relay Contacts

Noboru Wakatsuki; Nobuo Takatsu; Toshiteru Maeda; Takayuki Kudo

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Takayuki Kudo

Ishinomaki Senshu University

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Masahiro Oikawa

Ishinomaki Senshu University

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Toshiteru Maeda

Ishinomaki Senshu University

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Takayuki Kudou

Ishinomaki Senshu University

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Daisuke Hara

Ishinomaki Senshu University

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