1、Designation: B 615 79 (Reapproved 2006)Standard Practice forMeasuring Electrical Contact Noise in Sliding ElectricalContacts1This standard is issued under the fixed designation B 615; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 the year of last 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 practice describes the practices and factors consid-ered to be most important in the measurement of
3、 electricalcontact 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
4、Data 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 cont
5、acts 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
6、.1.1.1 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 ve
7、rsa) 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 vo
8、ltages, 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 ac
9、ceptance 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
10、 duplicated 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 physi
11、cs 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 shoul
12、d be 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 conside
13、red 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
14、(Note 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 Com
15、mittee B02 on NonferrousMetals and Alloys and is the direct responsibility of Subcommittee B02.11 onElectrical Contact Test Methods.Current edition approved June 1, 2006. Published June 2006. Originallyapproved in 1979. Last previous edition approved in 2000 as B 615 79 (2000).1Copyright ASTM Intern
16、ational, 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 current of 100 mA from a c
17、onstant-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 the contacts being teste
18、d. 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.5.1.1.4 Circuit Arrangemen
19、tWhen 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 single setsof contacts si
20、nce 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 noise from nearby equip-ment
21、 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 Mechanical Parameters:5.1.2.1
22、 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 and lubricants, while le
23、ss 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 Environmental Conditions:5.1
24、.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 Gaseous EnvironmentConditions
25、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 (decreasing fre-quency capability)
26、: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 level or levels.6.3.2 Puls
27、e 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 the electromechanical dev
28、ice. 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 provides the basis forreasonab
29、le interpretation.8.1.1 The power source should be a battery or other powersupply of known characteristics.FIG. 1 Circuit DiagramB 615 79 (2006)28.1.2 The readout should be an oscilloscope or a recorderhaving a time constant appropriate for the application of thedevice under test. Often the time con
30、stant 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),9.1.4 Noise values as a
31、 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 specific typeof test appara
32、tus 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 mentionedin this standard. User
33、s 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 must be reviewed every
34、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 theresponsible technica
35、l 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 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 615 79 (2006)3
