1. Snubber capacitor

2. Sealing current

3. Contact cleaner

4. See also

5. References

6. Further reading

In electrical engineering, wetting current (sometimes also spelled as whetting current in archaic sources) is the minimum electric current needing to flow through a contact to break through the surface film resistance. It is typically far below the contact's nominal maximum current rating.^[1]

The film of oxidation occurs often in areas with high humidity. Providing a sufficient amount of wetting current is a crucial step in designing systems that use delicate switches with small contact pressure as sensor inputs. Failing to do this might result in switches remaining electrically "open" when pressed, due to contact oxidation.^[3][4]

Snubber capacitor

In some low voltage applications where switching current is below the manufacturer's wetting current specification, a capacitor discharge method may be employed by placing a small snubber capacitor across the switch contacts to boost the current through contact surface upon contact closure.^[3][6]

Sealing current

A related term sealing current (aka wetting current or fritt current) is widely used in the telecommunication industry describing a small constant DC current (typically 1-20 mA) in copper wire loops in order to avoid contact oxidation of contacts and splices. It is defined in ITU-T G.992.3 for "all digital mode ADSL" as a current flowing from the ATU-C (ADSL Linecard) via the phone lines to the ATU-R (CPE).^[7][8]

Contact cleaner

See also

• Wetting current in switches
• Coherer
• Contact resistance
• Contact protection
• Cathodic protection
• Anodic protection
• Electromigration
• Electrowetting

References

Further reading

• {{cite book |title=Ney Contact Manual - Electrical Contacts for Low Energy Uses |author-first=Kenneth E. |author-last=Pitney |edition=reprint of 1st |date=2014 |orig-year=1973 |publisher=Deringer-Ney, originally JM Ney Co. |asin=B0006CB8BC |url=http://www.deringerney.com/techpapers/abstract/?DocumentId=pnk8SYvTdl5PBEYgylFWFjQO5IfWmXnrKiYltdIYKjM%3d}} (NB. Free download after registration.)
• {{cite book |title=Electrical Contacts: Principles and Applications |author-first=Paul G. |author-last=Slade |edition=2 |date=2014-02-12 |orig-year=1999 |publisher=CRC Press, Taylor & Francis, Inc. |isbn=978-1-43988130-9 |work=Electrical and Computer Engineering |series=Electrical engineering and electronics |volume=105}}
• {{cite book |title=Electric Contacts: Theory and Application |author-first1=Ragnar |author-last1=Holm |author-link1=Ragnar Holm |author-first2=Else |author-last2=Holm |author-link2=Else Holm |editor-first=J. B. P. |editor-last=Williamson |edition=reprint of 4th revised |date=2013-06-29 |orig-year=1967 |publisher=Springer Science & Business Media |isbn=978-3-540-03875-7}} (NB. A rewrite of the earlier "Electric Contacts Handbook".)
• {{cite book |title=Electric Contacts Handbook |author-first1=Ragnar |author-last1=Holm |author-link1=Ragnar Holm |author-first2=Else |author-last2=Holm |author-link2=Else Holm |edition=3rd completely rewritten |date=1958 |publisher=Springer-Verlag |location=Berlin / Göttingen / Heidelberg, Germany |isbn=978-3-662-23790-8}} https://web.archive.org/web/20180520151548/http://www.gbv.de/dms/ilmenau/toc/176968075.PDF --> (NB. A rewrite and translation of the earlier "Die technische Physik der elektrischen Kontakte" (1941) in German language, which is available as reprint under {{ISBN|978-3-662-42222-9}}.)
• {{cite book |editor-first1=Eduard |editor-last1=Vinaricky |editor-first2=Karl-Heinz |editor-last2=Schröder |editor-first3=Josef |editor-last3=Weiser |editor-first4=Albert |editor-last4=Keil |editor-first5=Wilhelm A. |editor-last5=Merl |editor-first6=Carl-Ludwig |editor-last6=Meyer |author-first1=Manfred |author-last1=Huck |author-first2=Eugeniucz |author-last2=Walczuk |author-first3=Isabell |author-last3=Buresch |author-first4=Josef |author-last4=Weiser |author-first5=Lothar |author-last5=Borchert |author-first6=Manfred |author-last6=Faber |author-first7=Willy |author-last7=Bahrs |author-first8=Karl E. |author-last8=Saeger |author-first9=Reinhard |author-last9=Imm |author-first10=Volker |author-last10=Behrens |author-first11=Jochen |author-last11=Heber |author-first12=Hermann |author-last12=Großmann |author-first13=Max |author-last13=Streuli |author-first14=Peter |author-last14=Schuler |author-first15=Helmut |author-last15=Heinzel |author-first16=Ulf |author-last16=Harmsen |author-first17=Imre |author-last17=Györy |author-first18=Joachim |author-last18=Ganz |author-first19=Jochen |author-last19=Horn |author-first20=Franz |author-last20=Kaspar |author-first21=Manfred |author-last21=Lindmayer |author-first22=Frank |author-last22=Berger |author-first23=Guenter |author-last23=Baujan |author-first24=Ralph |author-last24=Kriechel |author-first25=Johann |author-last25=Wolf |author-first26=Günter |author-last26=Schreiner |author-first27=Gerhard |author-last27=Schröther |author-first28=Uwe |author-last28=Maute |author-first29=Hartmut |author-last29=Linnemann |author-first30=Ralph |author-last30=Thar |author-first31=Wolfgang |author-last31=Möller |author-first32=Werner |author-last32=Rieder |author-first33=Jan |author-last33=Kaminski |author-first34=Heinz-Erich |author-last34=Popa |author-first35=Karl-Heinz |author-last35=Schneider |author-first36=Jakob |author-last36=Bolz |author-first37=L. |author-last37=Vermij |author-first38=Ursula |author-last38=Mayer |title=Elektrische Kontakte, Werkstoffe und Anwendungen: Grundlagen, Technologien, Prüfverfahren |language=German |edition=3 |location=Berlin / Heidelberg / New York / Tokyo |publisher=Springer-Verlag |date=2016 |orig-year=1984 |isbn=978-3-642-45426-4}}
• {{cite web |title=Overcome Wetting Voltage and Current Limitations With an External Wetting Power Supply |author-first=Martin |author-last=Lee |publisher=Schweitzer Engineering Laboratories, Inc. (SEL) |type=Application note |id=AN20 16-01 |date=2016-01-11 |url=https://cdn.selinc.com/assets/Literature/Publications/Application%20Notes/AN2016-01_20160111.pdf?v=20160406-152853 |access-date=2018-05-21 |dead-url=no}}
• {{cite web |title=The Test, Usage and Maintenance of Power Switching Subsystems |author-first=Kevin |author-last=Paton |publisher=Teradyne, Inc. / IEEE |location=North Reading, MA, USA |isbn=978-1-4244-9363-0 |date=2011 |url=http://www.teradyne.com/File%20Library/Defense-Aero/Technical%20Papers/2011/Paton_The-Test--Usage-and-Maintenance-of-Power-Switching-Subsystems_2011.pdf |access-date=2018-05-21 |dead-url=no |archive-url=https://web.archive.org/web/20170916192848/http://www.teradyne.com/File%20Library/Defense-Aero/Technical%20Papers/2011/Paton_The-Test--Usage-and-Maintenance-of-Power-Switching-Subsystems_2011.pdf |archive-date=2017-09-16}}
• {{cite |title=Fretting corrosion in power contacts: Electrical and thermal analysis |author-first1=S. |author-last1=El Mossouess |author-first2=N. |author-last2=Benjemâa |author-first3=E. |author-last3=Carvou |author-first4=R. |author-last4=El Abdi |author-first5=L. |author-last5=Benmamas |author-first6=L. |author-last6=Doublet |date=2014 |url=https://hal.archives-ouvertes.fr/hal-01104802/file/Holm%202014%20fin%20(1).pdf |access-date=2018-05-21 |dead-url=no |archive-url=https://web.archive.org/web/20180521175550/https://hal.archives-ouvertes.fr/hal-01104802/file/Holm%25202014%2520fin%2520(1).pdf |archive-date=2018-05-21}}

• Genoplesium woollsii
• Geno Renard Atkins Jr.
• Genostomatidae
• Geno Studio
• Genota
• Genota mitriformis
• Genota nicklesi
• Genota papalis
• Genotina genotae
• Genotoxicant
• Genotype (album)
• Genotype (Textures album)
• Genotyping by sequencing
• Genoud
• Genova-Casella railway
• Genovaite Galenite
• Genovaite Sidagite
• Genova, Missouri
• Genova–Casella railway
• Genov, Daniel
• Genovefa Weber
• Genovesa cactus finch
• Genovesa cactus-finch
• Genovesa ground-finch
• Genovesa ground finch