IEICE Transactions on Electronics
Online ISSN : 1745-1353
Print ISSN : 0916-8524
Special Section on Recent Development of Electromechanical Devices (Selected Papers from IS-EMD2007)
A Study on Contact Spots of Earthquake Disaster Prevention Relays
Yoshitada WATANABEYuichi HIRAKAWA
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2008 Volume E91.C Issue 8 Pages 1211-1214

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Abstract
This paper reports on the effect of switching action on the contact surfaces of earthquake disaster prevention relays. Large-scale earthquakes occur frequently in Japan and bring extensive damage with them, and fire caused by electrical equipments is one example of the serious damage which can occur. Earthquake sensors capable of maintaining a high level of reliability when earthquakes occur play an important role as a means of minimizing this damage. For this reason, we carried out observations by focusing on samples which had either been subjected to an electric current of 10mA or 0.1A. The samples of 10mA exhibited low and constant contact resistance despite the addition of seismic motion, while the samples of 0.1A samples exhibited varying contact resistance and damage on their contact spots resulting from the addition of seismic motion. The sample surfaces were then observed using an atomic force microscope (AFM) in tapping mode and a surface potential microscope (SPoM). As a result, we found that even the unused earthquake disaster prevention relay (standard sample) which had a surface lined with asperities on its parallel striations formed by irregular protrusions due to dust and other deposits. In addition, scanning the contact surface with the SPoM at the same potential revealed the occurrence of differences in surface potential which varied in response to the asperities on the striations.
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© 2008 The Institute of Electronics, Information and Communication Engineers
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