Entity

Time filter

Source Type

Kawasaki, Japan

Ishii M.,University of Tokyo | Saito M.,University of Tokyo | Fujii F.,University of Tokyo | Sugita A.,Franklin Japan Corporation
2010 Asia-Pacific Symposium on Electromagnetic Compatibility, APEMC 2010 | Year: 2010

It was revealed that serious lightning faults of high voltage power transmission lines in winter along the coastal area of the Sea of Japan were due to upward lightning initiated from transmission towers. Wind turbines in the same region, reportedly suffer from high lightning fault rate, must also generate frequent upward lightning. Taking account of the aerological data which indicate the heights of the charged region in thunderclouds, a method to evaluate frequency of upward lightning from tall structures in cold regions of Japan in winter is proposed. With this new method, it is possible to evaluate the probability of lightning hits to tall structures in Japan through the year. © 2010 IEEE.


Fujii F.,University of Tokyo | Ishii M.,University of Tokyo | Saito M.,University of Tokyo | Matsui M.,Franklin Japan Corporation | Natsuno D.,Toyo Sekkei
IEEJ Transactions on Power and Energy | Year: 2011

Wind turbines on the coast of the Sea of Japan have been damaged by lightning in winter. This is due to the frequent occurrence of upward lightning from wind turbines in winter. Occurrence of upward lightning turned out to be closely related to temperature distribution in high altitude. In this paper, correlation between lightning hits of wind turbines and the height of -10°C layer is analyzed. When an upward lightning hits a wind turbine in winter, the height of -10°C layer was lower than 2000 m in most of the cases. Moreover, winter lightning is classified into two types, namely storm type and inactive type, and it is found that parameters of lightning current observed by LLS differ depending on the type of lightning storms. © 2011 The Institute of Electrical Engineers of Japan.


Ishii M.,University of Tokyo | Saito M.,University of Tokyo | Fujii F.,University of Tokyo | Matsui M.,Franklin Japan Corporation | Natsuno D.,Toyo Sekkei
2011 7th Asia-Pacific International Conference on Lightning, APL2011 | Year: 2011

In Japan, transmission lines or wind turbines in the coastal area of the Sea of Japan have suffered from higher frequencies of serious troubles by lightning in winter than those in summer. The thunderstorm days in this area are comparable in winter to those of summer; however, the number of lightning strokes observed by lightning location systems (LLS) in winter is much smaller. In winter, concentration of lightning hits to tall structures is observed by LLS in the coastal area of the Sea of Japan. Out of the observation by LLS, the authors propose an experimental formula to estimate the frequency of upward lightning occurring on tall structures in winter in Japan. © 2011 IEEE.


Saito M.,University of Tokyo | Ishii M.,University of Tokyo | Fujii F.,University of Tokyo | Matsui M.,Franklin Japan Corporation
IEEJ Transactions on Power and Energy | Year: 2012

Seasonal variations of number of high current lightning discharges exceeding 100 kA observed by JLDN (Japanese Lightning Detection Network) were analyzed. The months with averaged altitudes of -10°C level higher than 5.7 km are classified as ordinary summer from the viewpoint of lightning activity. Meanwhile, on the coast of the Sea of Japan, more than 90% of negative high current lightning discharges were -GC (Ground to Cloud) strokes in the months when monthly averaged altitudes of -10°C level are lower than 2.7 km. These months are classified as the winter lightning season when upward lightning flashes frequently occur. Months other than winter or summer are classified as spring or autumn. In these seasons, the proportions of positive high current lightning discharges are higher than those of negative discharges like winter. Thus, the charge structure in the thunderclouds of spring and autumn may be similar to that in winter, and high current lightning strokes tend to occur. Since this variation of seasons is different in each area of Japan, relation of seasons, areas, and densities of high current lightning discharges were analyzed. © 2012 The Institute of Electrical Engineers of Japan.


Yanagawa S.,Shoden Co. | Yamamoto K.,Chubu University | Naito Y.,Shoden Co. | Takahashi N.,Nissan Motor Co. | Matsui M.,Franklin Japan Corporation
Electric Power Systems Research | Year: 2015

Many kinds of electronic equipment have been used in recent automobiles. Eco-friendly automobiles such as electric, fuel-cell and hybrid vehicles have spread rapidly. Those automobiles are usually sensitive to electromagnetic disturbance caused by lightning and so on. When an automobile is struck by lightning, lightning current usually flows into the earth through the vehicle body. The corresponding transient electromagnetic fields appearing inside the vehicle and shunt lightning current through electronics systems are considered sources of malfunctions. From an automobile safety and equipment protection viewpoints, investigations of protective measures are imperative. Before lightning protection methodologies are proposed, existing lightning damages to automobiles must be clarified. The statistical data on automobile lightning damage reports by conducting field surveys and web-based researches had been gathered. In this paper, the result of statistical data has been introduced. Right in the middle of the field surveys of lightning protection for automobiles, the outstanding fire accident of an automobile in Kanto district in Japan occurred. Right after hearing the news, interviews against the fire fighters about their field survey had been conducted; the scene of the accident and burned automobile had also been investigated. In this paper, the results of the interview and investigation have also been discussed. © 2015 Elsevier B.V.

Discover hidden collaborations