• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.204-205
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• 2006

This paper describes the protective ability of lightning arrestor in combined distribution system with power cable. To evaluate the protective ability, change of arrestor and grounding location are considered. On the other hand, arrestor developed by Cooper Power Systems for underground power cable system, is considered to evaluate surge protective ability as in underground system, when arrestor occurs failure has overhead line. The result shows that lightning arrestor in combined distribution system with power cable protect effectively when failure at arrestor in overhead line. On the other hand, arrestor developed by Cooper Power Systems for underground power cable system, is considered to evaluate surge protective ability in underground distribution system, when arrestor of overhead line has failure. The result shows that lightning arrestor installed in underground cable can effectively protected cables from surge when arrestor of overhead line has failure. And also even though grounding locations are decreased, it is revealed that protective ability is nearly similar.

• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.9-11
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• 2008

Lightning has been identified as one of the leading causes of outages on transmission and distribution systems. To protect the transmission and distribution line from lightning, the transmission lightning arrestor can be the effective facility on the power system. This paper will discuss Gapped type Arresters application results by analysing effects of lightning arrestors on transmission and distribution line.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.826-832
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• 1998

In this study the thin films with the structure of Si+SiO$_2$+TiN are made by RF supttering method. TiN, which has small diffusion coefficient and low resistivity, is evaporated between SiO$_2$ and Al layers. It investigates the V-R characteristics depending on the thickness of SiO$_2$ which is used as insulation layer and researches its effects on voltage stability of thin film and varistor. These films show very small resistance valus in negative(-) voltage and large and large value in positive voltage band, and with the increase of voltage, resistance value is rapidly reduced and the satisfactory characteristic of varistor is shown at +1[V]. It is found that resistance value of TiN thin film is small and also TiN thin film has more current than the thin film which is not evaporated by TiN thin film. When Al electrode is evaporated of SiO$_2$ thin film, spiking occurs, but the spiking can be prevented with evaporation of TiN between SiO$_2$ and Al layers and this thin films in made easily because of its good attachment. With the increase of voltage, the resistance is changed into non-linear pattern and the bidirectional varistor characteristic is shown and then its theory can be verified by this experiment. Accordingly, when TiN is evaporated of Si Wafer(n-100), it obtains better voltage-resistance than thin film which is not evaporated and also when varistor character is used electrically to automatic control element such as elimination of flame, power distribution arrestor and constant voltage compensation, satisfactory reproducibilities are expected.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1297-1302
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• 2004

In DC power distribution system for urban rail transits potential relay, 64P, is used to detect the ground faults. The problem with this 64P is that though it detects the ground fault it cannot identify the faulted region. Therefore the faulted region cannot be isolated properly. It could results in power loss of the trains on the healthy regions and the safety of the passengers in the trains could be affected adversely. A new ground fault protective relaying scheme that can identify the faulted region is presented in this paper. The new concept uses the current differential scheme and the permissive scheme to identify the faulted region correctly. A device with similar characteristic to the arrestor is adapted to use the current relay for the ground fault detection. The role of the device is to block the ground leakage current in normal operating condition and enable the ground fault current to flow in ground fault condition. The algorithm of the new relay and the effect of the newly adapted device in the new relaying scheme are discussed.