1、Designation: B615 79 (Reapproved 2011)Standard Practice forMeasuring Electrical Contact Noise in Sliding ElectricalContacts1This standard is issued under the fixed designation B615; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice describes the practices and factors consid-ered to be most important in the measurement of el
3、ectricalcontact noise of sliding contacts.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 become familiarwith all hazards including those identified in the appropriateMaterial Safety Dat
4、a Sheet (MSDS) for this product/materialas provided by the manufacturer, to establish appropriatesafety and health practices, and determine the applicability ofregulatory limitations prior to use.2. Terminology2.1 Definitions:2.1.1 contact noise, nthe varying voltage across a pair ofelectric contact
5、s due to conditions at their interface. It is to bedistinguished from the variation of signal due to its transmis-sion through electrical conductors (that is, induced voltagesdue to adjacent sources). It is also to be distinguished fromacoustic noise which may be generated by the contact action.2.1.
6、1.1 DiscussionStepwise change of resistance of awirewound potentiometer due to the definite resistance of asingle turn is not electrical contact noise.2.1.2 switching or edge noise, nthe electrical contactnoise occurring during the period of transition from conductionto non-conduction (or vice versa
7、) of a switching device.3. Significance and Use3.1 Resistance or voltage values alone do not providesufficient detail for an engineering evaluation of contact noise.This practice lists the test conditions that should be reportedwith noise measurements and indicates some conditions (opencircuit volta
8、ges, currents, etc.) that have been used for qualitycontrol and research studies. The use of these practices shouldprovide sufficient detail for an engineering interpretation of thenoise data and allow the tests to be repeated by anotherlaboratory.4. Types of Testing4.1 Type IQualification and accep
9、tance testing of electro-mechanical devices when low electrical contact noise isimportant for proper functioning.4.1.1 Electrical and mechanical parameters should closelysimulate the end use of the device.4.1.2 Since the procedure is used as a method of qualitycontrol, the test parameters must be du
10、plicated each time thetest is conducted.4.2 Type IIMeasurement of contact voltage variation as amethod of studying tribological phenomena.4.2.1 Tests are designed with specific diagnostic or researchgoals.4.2.2 Electrical and mechanical parameters are based onconsiderations of basic contact physics
11、and not the engineeringrequirements of the device. Selected parameters may be variedas part of the test. For example, rotational rate of a slip ringmay be varied to determine the surface velocity at whichhydrodynamic lift becomes important.5. Test Conditions5.1 The following test conditions should b
12、e controlled orknown to enable adequate evaluation of test results:5.1.1 Electrical Parameters:5.1.1.1 CurrentContact current and waveform should bespecified. The limitations of the instrument(s) being used tomeasure the noise and adequacy of shielding from extraneousnoise sources must be considered
13、 when current level is chosen.Type I tests may be made either at current levels chosen tosimulate those required in actual use or may be at highercurrent levels in order to enhance test sensitivity provided anysuch higher current magnitude shall be agreed upon betweenthe device user and producer (No
14、te 1).5.1.1.2 Source VoltageThe maximum open-circuit volt-age (to the contacts) and the impedance of the source should bespecified. In Type I tests, the open-circuit voltage levels chosenshould simulate those required in actual use and may be at1This practice is under the jurisdiction of ASTM Commit
15、tee B02 on NonferrousMetals and Alloys and is the direct responsibility of Subcommittee B02.11 onElectrical Contact Test Methods.Current edition approved Oct. 1, 2011. Published October 2011. Originallyapproved in 1979. Last previous edition approved in 2006 as B615 79 (2006).DOI: 10.1520/B0615-79R1
16、1.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.more than one level if representative of the end use (Note 1).In Type II tests, any voltage levels may be used depending onthe objectives of the studies being made (Note 2).NOTE 1A cu
17、rrent of 100 mA from a constant-current (d-c) sourcewith a 6-V maximum open-circuit voltage is often used for Type I testingof miniature slip ring-brush units intended for use in inertial guidancesystems.NOTE 2In Type II tests, one must consider the softening, melting, andarc-sustaining voltages of
18、the contacts being tested. Also, if it is notdesirable to frit (electrically puncture) organic or oxide surface films, anopen-circuit voltage of 20 mV or less must be used.5.1.1.3 LoadThe impedance of the load should be de-fined. Capacitive and inductive loads may affect the observedcontact noise.5.
19、1.1.4 Circuit ArrangementWhen multiple circuits are tobe tested on a sliding contact device the arrangement of thecircuits should be defined (for example, single circuit, pairs,multiple circuits in series). Circuit pairs are often monitored forType I tests. Type II tests will often be conducted on s
20、ingle setsof contacts since fundamental interpretations are simpler.5.1.1.5 Detector CharacteristicsThe type of detectorshould be defined along with its input impedance, resistance,and frequency response.5.1.1.6 ShieldingThe entire circuit must be electricallyshielded to prevent pickup of stray nois
21、e from nearby equip-ment or power lines which will introduce erroneous results. Allmechanical apparatus must be well grounded. The baselinenoise should be recorded while the contacts are static. Thisvalue should be negligible when compared to the noisemeasured from the operating contacts.5.1.2 Mecha
22、nical Parameters:5.1.2.1 Contact Surface VelocitySince the dynamics ofthe contacts are dependent upon the surface velocity, it shouldbe defined for any test.5.1.2.2 Wipe RateThe frequency of wiping across anyspecified point of the contact surface should be defined. Morefrequent wipes disperse films
23、and lubricants, while less fre-quent wiping allows film formation which may cause contactnoise.5.1.2.3 Special ConditionsAdditional description may benecessary to define the mode of operation completely (forexample, amplitude and frequency of oscillation, duty cycle,reversal of direction).5.1.3 Envi
24、ronmental Conditions:5.1.3.1 Temperature of TestTemperature should be speci-fied and held within specific limits.5.1.3.2 LubricationLubrication of the contacts should beheld constant to allow duplication of test. The type, thickness,and method of lubricant application requires control.5.1.3.3 Gaseou
25、s EnvironmentConditions should be de-fined as completely as possible. At least a designation such as“laboratory atmosphere,” “closed glass chamber,” or “enclosedwith drive motor,” should be included in the test description.6. Apparatus and Techniques6.1 Peak (-to-Peak) Instantaneous Noise (decreasin
26、g fre-quency capability):6.1.1 Oscilloscope.6.1.2 Optical Recorder.6.1.3 Peak-Reading Voltmeter.6.1.4 DArsonval Recorder.6.1.5 Servo Recorder.6.2 RMS Noise:6.2.1 True RMS Voltmeter.6.2.2 Average to RMS Converting Voltmeter.6.2.3 Servo Recorder.6.3 Special Techniques:6.3.1 Pulse Count, at specific le
27、vel or levels.6.3.2 Pulse Duration, at specific level or levels.6.3.3 Spectrum Analysis.6.3.4 Power Spectral Density.6.3.5 Missing Pulse Count.6.3.6 Pulse Alteration (phase, amplitude).6.3.7 Transient Recorder.7. Sampling7.1 The sampling plan should be as mutually agreed by theproducer and user of t
28、he electromechanical device. Manyassemblies (for example, slip ring capsules for inertial guid-ance platforms) are 100 % tested.8. Procedure8.1 The procedure that follows is generally accepted bymost organizations performing electrical contact noise tests. Itrequires the minimum equipment and provid
29、es the basis forreasonable interpretation.8.1.1 The power source should be a battery or other powersupply of known characteristics.FIG. 1 Circuit DiagramB615 79 (2011)28.1.2 The readout should be an oscilloscope or a recorderhaving a time constant appropriate for the application of thedevice under t
30、est. Often the time constant is less than 0.01 s.8.1.3 The circuit should be as shown in Fig. 1.9. Record9.1 The report of the noise test should include at least thefollowing details:9.1.1 Type of test (Section 4),9.1.2 Conditions of test (Section 5),9.1.3 Technique of noise measurement (Section 6),
31、9.1.4 Noise values as a function of test time (the noise canbe reported as a resistance or a voltage),9.1.5 Record of base line noise (5.1.1.6), and9.1.6 Specification requirements (Type I tests) or objectivesof test (Type II).10. Precision and Bias10.1 The precision and bias will depend on the spec
32、ific typeof test apparatus and test methods as described in Section 6.11. Keywords11.1 circuit; contacts; electrical; electrical contacts; noise;resistance; sliding; voltageASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentione
33、din this standard. Users of this standard are expressly advised that determination of the validity of any such patent 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
34、must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either 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
35、theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair 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 C
36、700, 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).B615 79 (2011)3
