Nishi Nippon Electrical Wire and Cable Co.

Ōita-shi, Japan

Nishi Nippon Electrical Wire and Cable Co.

Ōita-shi, Japan
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Aihara S.,Nishi Nippon Electrical Wire and Cable Co. | Shimoji H.,Oita University | Todaka T.,Oita Prefectural Organization for Industry Creation | Enokizono M.,Oita Prefectural Organization for Industry Creation
IEEE Transactions on Magnetics | Year: 2012

This paper presents measured local vector magnetic properties in a transformer type model core made of a laser-scratched grain-oriented electric steel sheet by using a vector-hysteresis (V-H) sensor. The V-H sensor consists of B-needle probes for measurement of the magnetic flux density vector B and double H-coil for measurement of the field strength vector H. The distance between the B-needle probes was shortened to be 2.5 mm and a 2 mm × 2 mm-sized double H-coil was mounted on the sensor head to realize higher resolution. The measurement accuracy of the B-needle probes was confirmed with a spatial probe, which can change the needle distance from 2 mm to 20 mm. The results show that the detailed local two-dimensional vector magnetic properties depending on laser-scratches are measurable with the developed new sensor. © 1965-2012 IEEE.


Aihara S.,Nishi Nippon Electrical Wire and Cable Co. | Aihara S.,Oita University | Shimoj H.,Oita Prefectural Organization for Industry Creation | Shimoj H.,Oita University | And 2 more authors.
IEEJ Transactions on Fundamentals and Materials | Year: 2012

This paper presents a 2.5 ×2.5 mm sized two-dimensional vector magnetic sensor (V-H sensor). The V-H sensor consists of B-needle probes for measurements of localized magnetic flux density vector B and a double H-coil for measurements of magnetic field strength vector H. The H-coil is made in very small size and the outside dimension is 2 mm × 2 mm and the distance between B-needles is 2.5 mm. In this paper, accuracy of the B-needle probe and frequency characteristic of the H-coil are evaluated and detailed two-dimensional vector magnetic properties in a magnetic circuit model made of a grain-oriented electric steel sheet are measured with the developed V-H sensor and results are compared with the crystal grain structure. © 2012 The Institute of Electrical Engineers of Japan.


Kanazawa S.,Oita University | Enokizono M.,Oita University | Shibakita T.,Nishi Nippon Electrical Wire and Cable Co. | Umehara E.,Nishi Nippon Electrical Wire and Cable Co. | And 4 more authors.
IEEJ Transactions on Fundamentals and Materials | Year: 2012

In recent years, inverter drive machines such as a hybrid vehicle and an electric vehicle are operated under high voltage pulse with high repetition rate. In this case, inverter surge is generated and affected the machine operation. Especially, the enameled wire of a motor is deteriorated due to the partial discharge (PD) and finally breakdown of the wire will occur. In order to investigate a PD on a resistant enameled wire, characteristics of PD in the twisted pair sample under bipolar repetitive impulse voltages are investigated experimentally. The relationship between the applied voltage and discharge current was measured at PD inception and extinction, and we estimated the repetitive PD inception and extinction voltages experimentally. The corresponding optical emission of the discharge was also observed by using an ICCD camera. Furthermore, ozone concentration due to the discharge was measured during the life-time test of the resistant enameled wires from a working environmental point of view. © 2012 The Institute of Electrical Engineers of Japan.


Kitajima J.,University of Miyazaki | Sakoda T.,University of Miyazaki | Watanabe K.,Nishi Nippon Electrical Wire and Cable Co.
IEEJ Transactions on Fundamentals and Materials | Year: 2014

To locate partial discharges (PDs) in cross-bonding cables where current pulses due to PDs might be divided, we paid attention to phases of current pulses obtained by six CT sensors arranged at both sides of 3-phase of the cables. The accuracy of PD location, obtained by using time difference between arrival times of current pulses from specified phase, was relatively high even for cross-bonding cables. © 2014 The Institute of Electrical Engineers of Japan.


Aihara S.,Nishi Nippon Electrical Wire and Cable Co. | Aihara S.,Oita University | Todaka T.,Oita University | Enokizono M.,Oita University
Przeglad Elektrotechniczny | Year: 2011

Two-dimensional vector measurement has become popular as an accurate evaluating method, which can measure the relationship between the magnetic flux density vector B and the magnetic field strength vector H. In order to improve the resolution of the two-dimensional vector magnetic measurement, 4mm-square-sized double H-coil was manufactured and evaluated with a developed evaluation system, which consists of a standard solenoid coil and a high-precision turntable. The V-H sensor combined the H-coil with double needles, was applied to measure distributions of local magnetic characteristics in a model core.


Ooka K.,Oita University | Kajiwara T.,Oita University | Aihara S.,Nishi Nippon Electrical Wire and Cable Co. | Enokizono M.,Oita University
IEEE Transactions on Magnetics | Year: 2014

To reduce power loss of transformers further from now on and to raise efficiency, we have measured magnetic property distributions in a three-phase tripod V-connection transformer model core. For the measurement, we have developed a localized vector magnetic property measurement system consisting of a three-axis positioning system, a vector magnetic sensor (V-H sensor), and PC. The measured results showed that rotational magnetic fluxes with a large axis ratio were generated in the V-junction parts of the transformer model core, and large iron loss was observed. To reduce the iron loss near the V-junction parts, we have tried to change local magnetic characteristics of the electrical steel sheet near the V-junction parts by using laser irradiation. The effect of the laser irradiation on the local magnetic properties is evaluated by measuring distributions of the local magnetic properties. © 1965-2012 IEEE.


Aihara S.,Nishi Nippon Electrical Wire and Cable Co. | Todaka T.,Oita University | Enokizono M.,Oita University
Journal of Electrical Engineering | Year: 2013

This paper presents a small-sized vector-hysteresis sensor (V-H sensor), which consists of piercing B-needles and double Hcoil. The B-needle probe can break through the insulation coating of silicon steel sheets like a drill. The H-coil is made in very small size and the outside dimension is 4mm×4mm. The magnetic flux density vector B and the field intensity vector H are measured with the B-needle probe and the double H-coil, respectively. The influence of the insulation coating on distributions of vector magnetic properties in transformer model cores is investigated in measurements with the developed very small-sized V-H sensor.© 2010 FEI STU.

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