1、Designation:B54213Standard Terminology Relating toElectrical Contacts and Their Use1This standard is issued under the fixed designation B542;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parent
2、heses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 The terms included in this list are those that are peculiarto electric contacts or general terms that have a specificmeaning when related to electric conta
3、cts.The definitions wereprepared assuming that the reader has a general knowledge ina physical science but is unfamiliar with the terminology of theliterature of electric contacts.2.Significance and Use2.1 The terms in this standard are used in standards andliterature related to electric contacts,ma
4、terials for electriccontacts and test methods for evaluating electric contacts.These terms may be difficult to locate in a general purposedictionary or the definition in such a dictionary may not coverthe meaning applied in the field of electric contacts.3.Terminologya-spotthe areas of two mating co
5、ntacts through whichcurrent flows from one contact to the other.activationa process in which contamination of the surface ofcontacts causes arcing at lower than usual voltage or arcingpersists at lower than usual current,or both.For example,palladium contacts operated in an organic vapor producearcs
6、 at voltage and current less than the minimum arcingvoltage and current because of the presence of carbon on thecontact surfaces.anode fallthe potential difference between the anode and theelectrical discharge plasma.anodic(anode)material transfersee material transfer.arc dischargea self-sustaining,
7、high current density,hightemperature discharge,uniquely characterized by a cathodefall nearly equal to the ionization potential of the gas orvapor in which it exists.arc,anodethe arc that occurs at less than a critical electrodespacing(see arc,cathode),and results in anode materialloss.arc,cathodeth
8、e arc that occurs at greater than a criticalelectrode spacing(see arc,anode),and results in cathodematerial loss.arc,shortesta limiting state of an arc in which the total arcvoltage approaches the sum of the cathode and anode falls.blowoutthe displacement and lengthening of an arc tofacilitate its e
9、xtinction.The blowout effect can be achievedby a magnetic field,air blast,etc.brusha sliding contact member consisting of one or moresliders(see sliders).cathode fallthe potential difference between the cathode andthe electric discharge plasma.cathodic(cathode)material transfersee material transfer.
10、constriction resistancethe increase in resistance arisingfrom a change in current density distribution.In electriccontacts it is that portion of contact resistance resulting fromthe convergence of current into the a-spots.contact,n(a)a generic term that applies to a device or partof a device and tha
11、t has the capability of completing orinterrupting the flow of an electrical signal in a circuit,(b)may also be used with modifiers such as:electrical contact,arcing contact,noble metal contact,separable contact,etc.contact,adjcontact area,the part of an electrical device thatis actually touching and
12、 where the electrical signal isexpected to pass.Contact member,one of the electrical pathparts that can make or break an electrical path.contact,arcingan electrical contact whose primary mode ofwearout occurs on the contacting surfaces as a result of anarc formed between separating or closing contac
13、t pairs.contact bouncethe unwanted operation of contacts immedi-ately following intentional operation.contact(s),buttinga type of contacts in which the directionof the motion of the moving contact is perpendicular to thecontact faces.The contacts close and open with no appre-ciable sliding or rollin
14、g action.contact chatterthe unwanted operation of contacts resultingfrom external forces operating on them.For example,vibration may cause contacts to open and close or“chatter.”1This terminology is under the jurisdiction of ASTM Committee B02 onNonferrous Metals and Alloys and is the direct respons
15、ibility of SubcommitteeB02.91 on Editorial and Terminology.Current edition approved Feb.1,2013.Published March 2013.Originallyapproved in 1932.Last previous edition approved in 2007 as B542 07.DOI:10.1520/B0542-13.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19
16、428-2959.United States1 contact-closing forcethe transient force between contactsduring closure.At the first instant of closure this force iszero.It then builds up to a maximum value dependent on theforces and inertia of the contact system and finally stabilizesat the static contact force.contact,compositea contact made of two or more distinctmaterials or alloys bonded to each other.For example,acontact with a facing of a precious metal bonded to abase-metal backing.contact forcethe force to clo
