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Underhållsåtgärder för säkerhetsreläer
RISE, Swerea, Swerea KIMAB.
2012 (Swedish)Report (Refereed)
Abstract [sv]

This project is a continuation of a previous project ”Environmental resistance of and effects of environmental impact on electronic and electro mechanical railway safety equipment – pre-study”, project HK 06-1340/AL50, concerned with climatic effects on and technical life of safety relays. The aim of this project is to increase possibilities of continued use of safety relays, primarily JRK relays, relays presently discarded due to visible surface films on contact areas or due to high contact resistance. Based on EDS-analysis, the main reason for high contact resistance is concluded to be carbon on contact surfaces. The carbon is likely from electrical decomposition of organic substances when closing or opening the contacts. In many cases, silicon is found on contact surfaces; electrical breakdown of silicone can thus be a contributing factor to high contact resistances. As a method to recondition contacts with high resistance, a contact burnishing tool can be used to remove, parts of, the surface film. Removal of loose particles is essential and can be done using a strip of ”bond paper”. Since the cleaning operation will move contaminants around, possibly deteriorating performance, contacts should not be cleaned unless needed. There are further indications of metal being transferred from the contact burnishing tool (stainless steel i.e. iron, chromium and nickel) to the silver surface, at the same time as insufficient contact cleaning will just move surface contaminants around. Since silicone contamination is believed to be one of the causes of high contact resistance, effects of adding a fluoropolymer film to prevent silicone oil spread are investigated. Since it has not been possible to provide a sufficiently clean surface by cleaning contacts without disassembling the relay, adding fluoropolymers to prevent creep of silicone oil is concluded not to be very useful. Besides the relay contact, the contact between the two contact rivets, there is a contact between the rivet and the contact spring. Resistance of this contact is about 0,1mW. Higher resistance has been measured for some relays, indicating low contact force. This is assumed to be due to the manufacturing process and not only to the age of the relay, the oldest relays not being the worst. Contact cleaning instructions are enclosed to the report.

Place, publisher, year, edition, pages
Swerea KIMAB AB , 2012. , p. 128
Series
Rapport / Institutet för metallforskning, ISSN 1403-848X ; KIMAB-2012-112
National Category
Materials Engineering
Identifiers
URN: urn:nbn:se:ri:diva-13031OAI: oai:DiVA.org:ri-13031DiVA, id: diva2:973225
Available from: 2016-09-22 Created: 2016-09-22Bibliographically approved

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CiteExportLink to record
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  • apa
  • harvard1
  • ieee
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  • vancouver
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  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
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Output format
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