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Zinc oxide surge arresters using zinc oxide (ZnO) elements have been widely used for insulation coordination in the world power systems. These ZnO elements have basically reference voltage of about 200 V/mm. Recently, new ZnO elements having about 1.5, 2 times high voltage gradient zinc oxide element have been developed. This paper describes applications of high voltage gradient 300 V/mm ZnO elements to high performance porcelain type surge arresters and oil immersed surge arresters, and 300 V/mm or 400 V/mm ZnO elements to gas insulated tank type surge arresters for power system. Adequate selection of voltage gradient of ZnO elements makes more compact design of the surge arresters.

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High-performance p-channel lateral double-diffused MOS (LDMOS) transistors designed to operate in a wide voltage range from 35 to 200 V and built using silicon-on-insulator LDMOS platform technology were studied. A novel channel structure was applied, and consequently, a high saturation drain current of 172 μA/μm in the 200-V p-channel LDMOS transistor was achieved, which is comparable to that of an n-channel LDMOS transistor. A low ON-resistance of 3470 mΩ · mm 2 was obtained while maintaining high ON-and OFF-state breakdown voltages of −240 and −284 V. The 35-200-V LDMOS transistors with low ON-resistance were also demonstrated by optimizing the layout, i.e., the reduced surface field structure and field plates. Index Terms-High-voltage (HV) techniques, power MOSFETs, power semiconductor devices, silicon-on-insulator (SOI) technology.Satoshi Shimamoto received the M.S. degree from The University of Electro-Communications, Tokyo, Japan.Since 1999, he has been with the Micro Device Division, Information and