1、Designation: B 576 94 (Reapproved 2005)Standard Guide forArc Erosion Testing of Electrical Contact Materials1This standard is issued under the fixed designation B 576; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers the major variables which affect therate of arc erosion of electrical contact materials and serves asa
3、 guide in developing more detailed specifications for arc-erosion tests.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine t
4、he applica-bility of regulatory limitations prior to use.1.3 Arc erosion testing involves some vaporization of ma-terial. It is the responsibility of the user to become familiarwith all hazards including those identified in the appropriateMaterial Safety Data Sheet for the material being tested.2. S
5、ignificance and Use2.1 The significance of the variables set forth in this guidewas proved by various laboratories using several test systemsat test currents ranging from 100 to 35 000 A. These variableswill be significant for any case where voltage and current aresufficient to produce arcing.3. Maj
6、or Variables3.1 Shape, Area, and Thickness:3.1.1 The area, shape, and thickness of the contact affect theerosion rates. As an example of shape effects, the radius of thespherical crown affects the erosion in at least two ways: (1)itchanges the effective diameter of the contact and, ( 2) it affectsth
7、e manner in which the arc moves about on the surface of thecontact. A contact with a hemispherical crown presents nosharp edges that would result in different amounts of erosionproducts for a given amount of arcing and aids in the control ofthe arc when operating in air and other gases.3.1.2 The con
8、tacts may be given a type of normal shape andsurface roughness by a number of arcing operations prior torecording the contact loss. There may be a difference in theeffect of shape and diameter for different environments.3.1.3 Contact mounting, attachment, and bond integrity canaffect the arc erosion
9、 of materials and should be specified.3.2 Contact Velocity and Maximum Arc LengthThe veloc-ity of separation and the maximum arc length affect the erosionrate and, therefore, should be specified in formulating a test.3.3 Contact Orientation:3.3.1 The orientation of the contacts with respect to theea
10、rths gravitational field may affect the erosion rate and,therefore, should be specified. For example, the mating planesof the contacts might be vertical or horizontal.3.3.2 If the contacts mating planes are horizontal and adirect test current is used, the specifications should statewhether the anode
11、 or cathode is in the upper position.3.4 Environment:3.4.1 The type, pressure, temperature, and humidity of thegas atmosphere or the type, pressure, and temperature of thesurrounding oil, affect the erosion rate and should be specified.3.4.2 The erosion rate in air may be quite different than thatun
12、der oil.3.5 Arcing Current:3.5.1 An increase in arc current will cause an increase in thearc-erosion rate per coulomb of arcing, and thus it must bespecified.3.5.2 It follows then that the wave form of the arc current isimportant and source voltage and load current should bespecified.3.6 Arcing Time
13、The time duration of individual arcs on anelectrical contact affects the erosion rate and thus it should bespecified.3.7 Closing Force, Speed, and BounceThe severity of thedamage caused by the closing arcs depends on the closingspeed, closing force, and the number of bounces. All thesethree can be m
14、easured. The arc erosion that occurs because ofclosing arcs caused by contact bounce can be duplicated byproperly specifying other items in this list with particularemphasis on contact velocity and maximum arc length. Un-wanted closing arcs can be effectively eliminated from acontact test device, fo
15、r example, by causing the test current toflow through the contacts after the contacts have been closed.1This guide is under the jurisdiction of ASTM Committee B02 on NonferrousMetals and Alloys and is the direct responsibility of Subcommittee B02.05 onPrecious Metals and Electrical Contact Materials
16、.Current edition approved Nov. 1, 2005. Published November 2005. Originallyapproved in 1973. Last previous edition approved in 1999 as B 576 94 (1999).1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.8 Contact Body TemperatureThe ma
17、ting contacts of acontact pair might have different temperatures and both shouldbe measured or specified just before the arcing operation.3.9 Total Number of Arcing OperationsThe total numberof arcs or, in other words, the time duration of the tests, mustbe specified for several reasons. First, the
18、shape of the contactmay change as the test progresses; secondly, chemical actionsmay take place to change the erosion rate as, for example, byformation of silver oxide on silver or tungsten oxide ontungsten.3.10 Arc MotionArc motion produced by any means, suchas magnetic fields, is important and sho
19、uld be specified.3.11 Polarity:3.11.1 Polarity may affect erosion rates and should bespecified, that is, is it constant or alternating.3.11.2 Tests in which the polarity is constant may givedifferent erosion rates than those in which the polarity changes.Polarity effect could cause different surface
20、 conditions forsuccessive arcs.3.12 Operation RateThe operation rate affects the oper-ating temperature of the contact and, therefore, the erosion rate.3.13 Opening Speed and Opening ForceThese two fac-tors affect the severity of the damage caused by the openingarc.4. Keywords4.1 arcing contacts; ar
21、c erosion; contacts; electrical con-tacts; electrical erosionASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such p
22、atent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited e
23、ither for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fai
24、r hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).B 576 94 (2005)2
