Hiroshi Hatano

Total-dose characterization of a high-performance radiation-hardened 1.0- mu m CMOS sea-of-gates technology

A radiation-hardened CMOS sea-of-gates technology with 1.0- mu m geometry is developed which is fully compatible with commercial technologies. Total-dose and postirradiation effects are investigated in detail on transistors and circuits designed on a 2K-gate test chip. The data show that this technology is radiation hardened up to a total dose of 1 Mrad(SiO/sub 2/) and may be functional at 10 Mrad(SiO/sub 2/). Moreover, using a simple analytic model for switching of CMOS circuits, it is shown that the changes in circuit performance are well correlated with those in transistor characteristics. >

Development of the world's largest hydrogen indirectly cooled turbine generator

Water-cooled stator-winding generators are widely used for large capacity turbine generators of thermal power plant. However, simpler stator cooling system is preferred considering easy operation and maintenance and lower cost. Hydrogen indirectly cooled generator is one of the solution with expansion its capacity. TOSHIBA has developed, manufactured and tested 670MVA hydrogen indirectly cooled generator.

Current progress in high thermal conducing insulation technology for large capacity turbine generator

We have enlarged the capacity of indirectly hydrogen-cooled turbine generators to improve the efficiency, simplify the machine structure and save the maintenance cost over the past decade. The one of the key technologies is the heat transfer from a stator bar conductor to iron core, because indirectly hydrogen-cooling performance is inferior to directly water-cooling one. So, we have developed High Thermal Conducting (HTC) insulation technology and achieved twice of thermal conductivity compared to conventional epoxy-mica insulation [1]. Recently, we have achieved further improvement in thermal conductivity of HTC insulation. The progress of HTC insulation technology is reported in this paper.

A study of trace gas detection based on cavity enhanced absorption spectroscopy (CEAS) for power transformer diagnosis

We apply CEAS technique to monitor trace acetylene gas in oil as marker of power transformer diagnosis. Developed CEAS sensor can detect trace acetylene gas as low as 8ppb in a few seconds.

Off-line and on-line detection of PD in inverter-fed random-wound motor considering IEC technical specifications

In the inverter-fed motor, the surge voltages with fast rise time and high voltage peak may cause partial discharge (PD) which potentially damages the electrical insulation system. Offline tests with an impulse generator are executed under the IEC technical specifications of TS60034-18-41 (2006) and TS61934 (2011) for insulation systems of low-voltage motors fed from inverters, which are required of PD free in their expected service lives. On-line tests are executed during operation of an actual motor fed from a PWM inverter, since the PD properties may differ from the off-lines ones. This paper mainly discusses the detection sensitivity of PD for off-line and on-line tests using the PD detector at motor terminal. Firstly, effects on PD signal at the motor terminal in the stator windings under surge voltage are examined, when PD signal propagates through some coils after generating PD in the twisted pair that is connected to the motor winding purposely. In our test conditions, it is confirmed that PD signal propagating through the motor winding to the motor terminal can be detected correctly. Secondly, effects of noises on detection sensitivity are examined. It is concluded that the residual surge noise signals from an inverter or an impulse generator can be excluded using the high-pass filter of the appropriate selected frequency, then PD signals can be easily recognized, even for on-line tests. Finally, the transient noises hardly have effect on the PD detection of offline tests under an IEC-TS61934, since the time range required for the PD distinction of off-line tests is extremely shorter than of power frequency tests. These testing results and considerations may be useful for the standardizations of the IEC TS60034-18-41 and TS 61934 in the near future.

Performance characteristics of a passively locked cavity-enhanced absorption spectrometer with wideband-tunable multimode near-infrared light source

A trace material detection system was developed on the basis of cavity-enhanced absorption spectroscopy (CEAS) using a fiber-coupled passively locked external cavity diode laser (PLEC-DL) in the near-infrared (NIR) wavelength region. The oscillation range of an antireflection-coated diode laser (AR-DL) coupled into an external cavity could be simply selected with a narrowband bandpass filter (1 nm), resulting in a stable wavelength oscillation in the wideband tunability between 1640 and 1680 nm. The external cavity acts as a trace material sensor that exhibits excellent flexibility because it is free from the DL source and is carefully designed with mirrors having reflectivities of ca. 99.995 and 99.99%. Trace-level detection was successfully demonstrated with the developed sensor having a minimum detectable absorption coefficient of 2.4 × 10−8 cm−1, which corresponds to 0.15 ppm for CH4 concentration without interference from H2O absorption lines under atmospheric pressure.

Advanced technology of stator winding insulation system for HV motors

To improve the reliability and the productivity of insulated windings for high voltage motors, we have developed the refined vacuum pressure impregnation (VPI) system. Higher thermal resistance and better impregnability have been achieved by new mica paper with small amounts of milled glass fibers in it. In this paper, we described the impregnability, the voltage endurance and the thermal resistance of our new VPI.