Plenary Lecture
Lightning Protection for Power Apparatuses
Professor Hitoshi Kijima
Polytechnic University
Japan
E-mail: hkijima@uitec.ac.jp
Abstract: This paper proposes a new technology for protecting power apparatuses against overvoltage or overcurrent caused by lightning surge. Surge Protective Devices (SPDs) are used for protecting apparatuses against overvoltage or overcurrent caused by lightning surge. SPDs are mainly divided into two categories. One is clamping type and the other is switching type. Typical clamping type SPD is a variable resitor (varistor). Typical switching type SPD is a Gas-filled Discharge Tube (GDT). Both varistors and GDTs have problems when using them alone. This paper proposes a lightning surge response improvement by combinations of both varistors and GDTs in order to solve the problems of them. It is that three or more GDTs are connected in series and two or more varistors are connected in parallel. Problems of both them can simultaneously be solved by reducing the operating voltage with high response time. A disconnector for an overvoltage protector is equipment that disconnects a circuit when the overvoltage protector may fail in a short circuit mode. The disconnector and the overvoltage protector are connected in series. A fuse or a circuit breaker is normally used as a disconnector. However there are problems with both methods. A fuse is not recyclable once it goes out. Even a circuit breaker is resettable, a lightning surge current causes switchgear of circuit breaker to open unnecessary. This malfunction spoils the overvoltage protective function which eliminates a lightning surge current into an instrument. If the problem which a switchgear of circuit breaker comes floating can be solved, even when a lightning surge current flows through it, an instrument can be protected by the overvoltage protector. This paper presents several approaches preventing circuit breaker type disconnectors from the malfunction.
Brief Biography of the Speaker:He was born in Yamanashi; Japan in 1952. He received his BS in Electrical engineering from Yamanashi University (1975), his MS in Electrical engineering from Yamanashi University (1977), and his Ph.D. from Tokyo University (1999).. His field is all EMC aspects such as lightning protection, noise reduction, earthing systems. He served 20 years in R&D center of NTT (Nihon Telegraph and Telephone public corporation). He was leader of EMC Department. Then He became professor of Polytechnic University. He published many books such as Recent Lightning Protection (ISBN4-542-30397-7) 2006, Electrical Engineering (ISBN4-87563-022-0) 2003, Earthing & Lightning Protection (ISBN4-88552-147-5) 2002. He obtained the best paper award for the 9th WSEAS International Conference (EHAC '10) University of Cambridge, UK, February 20-22, 2010, Electromagnetic Force Analyzed Results on Switchgear of Disconnector for Overevoltage Protector, pp.135-140 Hitoshi Kijima, Tomooki Hasegawa. Recent papers are as follows. [1] H. Kijima, K. Takato, K. Murakawa, Lightning protection for gas-pipelines installed under the ground, International Journal of systems and applications, engineering & development, Issue 1, vol. 5, pp117-126, 2011? [2] H. Kijima, T. Hasegawa, Electrical force analyzed results on switchgear of disconnector for overvoltage protector, WSEAS Transactions on power systems, Issue 1, vol. 5, pp32-41, 2010 [3] H. Kijima, M. Shibayama, Circuit breaker type disconnector for overvoltage protector, WSEAS Transactions on power systems, Issue 5, vol. 4, pp167-176, 2009 [4] H. Kijima, A Development of Earthing-Resistance-Estimation Instrument International Journal of geology, Issue 4, vol. 4, pp112-116, 2009.