1、Designation: B542 07B542 13Standard 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 num
2、ber in parentheses 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 peculiar to electric contacts or general terms that have a specific meaningwhen related
3、 to electric contacts. The definitions were prepared assuming that the reader has a general knowledge in a physicalscience but is unfamiliar with the terminology of the literature of electric contacts.2. Significance and Use2.1 The terms in this standard are used in standards and literature related
4、to electric contacts, materials for electric contacts andtest methods for evaluating electric contacts. These terms may be difficult to locate in a general purpose dictionary or the definitionin such a dictionary may not cover the meaning applied in the field of electric contacts.3. Terminologya-spo
5、tthe areas of two mating contacts through which current flows from one contact to the other.activationa process in which contamination of the surface of contacts causes arcing at lower than usual voltage or arcing persistsat lower than usual current, or both. For example, palladium contacts operated
6、 in an organic vapor produce arcs at voltage andcurrent less than the minimum arcing voltage and current because of the presence of carbon on the contact surfaces.anode fallthe potential difference between the anode and the electrical discharge plasma.anodic (anode) material transfersee material tra
7、nsfer.arc dischargea self-sustaining, high current density, high temperature discharge, uniquely characterized by a cathode fall nearlyequal to the ionization potential of the gas or vapor in which it exists.arc, anodethe arc that occurs at less than a critical electrode spacing (see arc,cathode), a
8、nd results in anode material loss.arc, cathodethe arc that occurs at greater than a critical electrode spacing (see arc,anode), and results in cathode material loss.arc, shortesta limiting state of an arc in which the total arc voltage approaches the sum of the cathode and anode falls.blowoutthe dis
9、placement and lengthening of an arc to facilitate its extinction. The blowout effect can be achieved by a magneticfield, air blast, etc.brusha sliding contact member consisting of one or more sliders (see sliders).cathode fallthe potential difference between the cathode and the electric discharge pl
10、asma.cathodic (cathode) material transfersee material transfer.constriction resistancethe increase in resistance arising from a change in current density distribution. In electric contacts it isthat portion of contact resistance resulting from the convergence of current into the a-spots.contact, n(a
11、)(a) a generic term that applies to a device or part of a device and that has the capability of completing or interruptingthe flow of an electrical signal in a circuit, (b)(b) may also be used with modifiers such as: electrical contact, arcing contact,noble metal contact, separable contact, etc.1 Th
12、is terminology is under the jurisdiction of ASTM Committee B02 on Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee B02.91 onEditorial and Terminology.Current edition approved May 1, 2007Feb. 1, 2013. Published May 2007March 2013. Originally approved in 1932. Last previou
13、s edition approved in 20042007 asB542 04.B542 07. DOI: 10.1520/B0542-07.10.1520/B0542-13.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible
14、to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Co
15、nshohocken, PA 19428-2959. United States1contact, adjcontact area, the part of an electrical device that is actually touching and where the electrical signal is expected topass. Contact member, one of the electrical path parts that can make or break an electrical path.contact, arcingan electrical co
16、ntact whose primary mode of wearout occurs on the contacting surfaces as a result of an arcformed between separating or closing contact pairs.contact bouncethe unwanted operation of contacts immediately following intentional operation.contact(s), buttinga type of contacts in which the direction of t
17、he motion of the moving contact is perpendicular to the contactfaces. The contacts close and open with no appreciable sliding or rolling action.contact chatterthe unwanted operation of contacts resulting from external forces operating on them. For example, vibration maycause contacts to open and clo
18、se or “chatter.”contact-closing forcethe transient force between contacts during closure. At the first instant of closure this force is zero. It thenbuilds up to a maximum value dependent on the forces and inertia of the contact system and finally stabilizes at the static contactforce.contact, compo
19、sitea contact made of two or more distinct materials or alloys bonded to each other. For example, a contact witha facing of a precious metal bonded to a base-metal backing.contact forcethe force to close, maintain, or open contacts. See also insertion force, withdrawal force, and normal force.contac
20、t noisea varying voltage across a pair of electric contacts due to conditions at their interface.contact, non-arcingmating electrical contact surfaces that do not experience wearout due to arc erosion that is opposite of arcingcontacts.contact, pitteda contact that has numerous discrete hollows in i
21、ts surface.contact pressurethe force per unit area of physical contact between two contacts. This term is frequently but improperly usedwhen contact force is meant. The area of physical contact is usually difficult to determine and quite different from the apparentarea of contact.contact resistancet
22、he resistance to current flow offered by the contact interface, comprising the sum of the constrictionresistance plus the film resistance.NOTE 1In a practical measurement, correction must be made for bulk resistance consisting of contact material, lead wires, etc.contact, screwa contact fabricated w
23、ith an external thread for attachment to a support member or for adjustment.contact, slidingan electric contact which is expected to do its primary function during sliding.contact, solida monolithic contact member.contact, springa contact system in which one piece of material is used for both the dr
24、iving spring and electric contact.contact, statican electric junction designed for infrequent separation and connection.contacts, wipingcontacts that have some sliding motion during opening or closing.contact wiperelative tangential motion between contacting surfaces that occurs during the normal co
25、urse of contact closure.corona (discharge)a self-sustaining discharge characterized by highly asymmetrical electric fields with the result that ionizationpredominantly occurs near the electrode with the higher potential gradient.crimp, vto establish an electrical and mechanical attachment between th
26、e two members by mechanically deforming one contactmember around another. In most cases, one member is a stranded or solid wire, or a group of wires, the other is a hollow cylinderor partial cylinder that is deformed around the wire(s).dark (or Townsend) dischargea discharge which may or may not be
27、self-sustaining. It is characterized by a uniform field,current in the microampere range, and a nonluminous inter-electrode space.electromigration(1)(1) Current-induced atomic diffusion in a solid metal due to electron momentum and the potential gradient,(2)(2) electrochemical process of growth of m
28、etallic path across an insulating surface under imposed electric field.DISCUSSIONThe solid state process may cause significant material transport in regions of high current density such as a-spots in contacts. In devices with electricalcontacts, the electrochemical process may form shorts between co
29、nductors under certain environmental conditions.B542 132film resistancethat portion of the contact resistance that is due to the presence of contaminants on one or both of the contactmembers.fine transfersee material transfer, bridge.fretting, nsmall amplitude oscillatory motion, usually tangential,
30、 between two solid surfaces in contact.DISCUSSIONHere the term fretting refers only to the nature of the motion without reference to the wear, corrosion, or other damage that may ensue. The termfretting is often used to denote fretting corrosion and other forms of fretting wear. Usage in this sense
31、is discouraged because of the ambiguity thatmay arise.fretting corrosiona form of fretting wear in which corrosion plays a significant role.DISCUSSIONIn electrical contact interfaces involving non-noble metals, fretting corrosion can cause rapid and substantial increases in contact resistance as a r
32、esultof localized appearance of insulating oxides and other corrosion products at the interface.fretting wearwear arising as a result of fretting. See fretting.friction polymerizationthe process by which organic compounds (such as adsorbed air pollutants) on mating surfaces that moverelative to each
33、 other polymerize to yield compounds of high molecular weight.NOTE 2When this occurs on electrical contacts and the materials formed remain on the surface, contact resistance may increase substantially. Thesolid materials that are produced by the polymerization process are called “friction polymers”
34、 or “frictional polymers.”fritting (A-fritting)an electric breakdown between mating metallic contacts, separated by an insulating film, which occurs whenthe field strength exceeds approximately 1 000 000 V/cm. Metallic bridges are produced through the film if the fritting voltageis above the contact
35、 melting voltage.fritting voltagethe voltage at which fritting occurs.glow dischargea self-sustaining discharge characterized by essentially symmetrical electrodes, low current density, and a highcathode fall of about 200 V.glowing connection (or contact), none that sustains emission of both visible
36、 light and heat while conducting electrical current.high resistancecontact resistance exceeding an arbitrary, specified limit.inrush currenta transient current that exists at the instant of contact closure and persists for a relatively short time.insertion forcethe force required to mate two connect
37、or halves.material transfera general term to describe the carry-over of material from one electrical contact to another.NOTE 3When the discussion becomes specific, the term “gain” or “ loss” is used with respect to a particular contact (for d-c application, anode orcathode; for a-c application, stat
38、ionary contact or movable contact). For example, anode gain, anode loss, stationary contact gain.material transfer, negativesee material transfer.material transfer, positivesee material transfer.material transfer, bridgematerial transfer that occurs without the presence of a gaseous electric dischar
39、ge. The filament ofmolten contact material that connects the two separating contacts does not rupture in the middle; thus there is a gain of materialon one contact and a loss of material from the other.material transfer, cathodemovement of contact metal from the cathode by means of a cathode arc.mat
40、erial transfer, needlematerial transfer that results in a buildup with a smaller diameter and a relatively great length.noiseSee contact noise.normal forcethat component of the force between contacting bodies perpendicular to their interface.opening forcethe force available to open the contacts.plas
41、maa partially or totally ionized gas or vapor.porosityin metallic coatings, the presence of any disontinuity, crack, or hole in the coating that exposes a different underlyingmetal.positive columnthat region of an electric discharge between the cathode and anode falls.B542 133screw contactsee contac
42、t, screw.self-sustaining dischargea discharge in which all carriers necessary for the transport of current in the discharge are producedby this discharge itself.showeringa particular form of corona discharge characterized by strongly ionized streamers or streams of luminous plasma. Itgenerally occur
43、s at a field value just below that which is required for a complete breakdown.sliderthat member of a sliding contact pair, normally the smaller, which may be moved through a range of locations on theopposing member.sliding electrical contactscontacting members that perform their function while under
44、going relative tangential motion.slip ringa continuous metal ring by means of which electrical current can be conducted to or from brush contacts. One electricalcontact member is designed to rotate with respect to the other.slip ring assemblytwo or more slip rings with connecting leads or terminals
45、that have been mounted to a common structure.slip ring capsulean assembly that includes a slip ring assembly, brushes, and bearings for conducting current on multiple circuitsfrom a stationary body to one that may rotate.spark, dischargea non-self-sustaining discharge characterized by high luminosit
46、y and a ratio of lateral dimension to length thatis substantially smaller than unity.sulfide creepin electrical contacts, spontaneous migration of a sulfide based corrosion product that occurs at elevated humidityacross a gold rich surface.DISCUSSIONThis process often involves copper sulfide produce
47、d by corrosion on a copper alloy spring that, under severe conditions, can completely cover a goldcontact mounted on the spring.tarnishthe chemical compound on the surface of a contact resulting from the reaction of the contact material and the inorganicconstituents of the surrounding atmosphere.twe
48、akto make a mechanical adjustment of a spring arm of an electrical contact assembly to adjust the force or position of thecontact.wipersee slider. The term “wiper” is sometimes used interchangeably with the more preferred term “slider.”withdrawal forcethe force required to separate two mated connect
49、or halves.B542 1344. Terminology Defined In Individual Standards For Electric Contact Test Methods And Electric Contact Materials4.1 The following terms are defined in the terminology sections of indicated standards.Aluminum B812Bulk Resistance B539, B812Conductor B868Connectability B896Connection Resistance B539Contact Noise B615Contact Performance B868Contact Resistance B667Contact Resistance Probe B667Corrosion Products B735, B799, B920Crimp B913Crimp Barrel B913Crimped Connection B913Crimp
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