ASTM F2249-2018 Standard Specification for In-Service Test Methods for Temporary Grounding Jumper Assemblies Used on De-Energized Electric Power Lines and Equipment.pdf

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1、Designation: F2249 18Standard Specification forIn-Service Test Methods for Temporary Grounding JumperAssemblies Used on De-Energized Electric Power Lines andEquipment1This standard is issued under the fixed designation F2249; the number immediately following the designation indicates the year oforig

2、inal adoption or, in the case of revision, the 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 These specifications cover the in-service inspection andelectri

3、cal testing of temporary protective grounding jumperassemblies which have been used by electrical workers in thefield.1.2 These specifications discuss methods for testing ground-ing jumper assemblies, which consist of the flexible cables,ferrules, clamps and connectors used in the temporary protec-t

4、ive grounding of de-energized circuits.1.3 Manufacturing specifications for these groundingjumper assemblies are in Specifications F855.1.4 The application, care, use, and maintenance of thisequipment are beyond the scope of this specification.1.5 Units of measurement used in this specification are

5、inthe Metric system (SI) with English units given in parentheses.1.6 The following safety hazards caveat pertains only to thetest portions of this specification. This standard does notpurport to address all of the safety concerns, if any, associatedwith its use. It is the responsibility of the user

6、of this standardto establish appropriate safety, health, and environmentalpractices and determine the applicability of regulatory limita-tions prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the D

7、ecision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2B172 Specification for Rope-Lay-Stranded Copper Conduc-tors Having Bunch-Stran

8、ded Members, for Electrical Con-ductorsB173 Specification for Rope-Lay-Stranded Copper Conduc-tors Having Concentric-Stranded Members, for ElectricalConductorsF855 Specifications for Temporary Protective Grounds to BeUsed on De-energized Electric Power Lines and Equip-ment2.2 IEEE Standards:3IEEE St

9、andard 802013 IEEE Guide for Safety in ACSubstation GroundingIEEE Standard 10482016 IEEE Guide for the ProtectiveGrounding of Power LinesIEEE Standard 12462011 IEEE Guide for Temporary Pro-tective Grounding Systems Used in Substations3. Terminology3.1 Definitions of Terms Specific to This Standard:3

10、.1.1 grounding jumper assemblygrounding cable withconnectors and ground clamps attached, also called a ground-ing jumper or a protective ground assembly installed tempo-rarily on de-energized electric power circuits for the purpose ofpotential equalization and to conduct a short circuit current fora

11、 specified duration (time).1This specification is under the jurisdiction of ASTM Committee F18 onElectrical Protective Equipment for Workers and is the direct responsibility ofSubcommittee F18.45 on Mechanical Apparatus.Current edition approved April 15, 2018. Published August 2018. Originallyapprov

12、ed in 2003. Last previous edition approved in 2015 as F2249-03(2015). DOI:10.1520/F2249-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Su

13、mmary page onthe ASTM website.3Available from the Institute of Electrical and Electronics Engineers, Inc. (IEEE)1828 L St., NW, Suite 1202, Washington, DC 200365104.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international sta

14、ndard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.14. S

15、ignificance and Use4.1 Grounding jumper assemblies can be damaged by roughhandling, long term usage, weathering, corrosion, or a combi-nation thereof. This deterioration may be both physical andelectrical.4.2 The test procedures in this specification provide anobjective means of determining if a gro

16、unding jumper assem-bly meets minimum electrical specifications. These methodspermit testing of grounding jumper assemblies under con-trolled conditions.4.3 Each responsible entity must determine the requiredsafety margin for their workers during electrical fault condi-tions. Guidelines for use in t

17、he determination of these condi-tions are beyond the scope of this specification and can befound in such standards as IEEE Standard 802013 and IEEEStandard 10482016, and IEEE Standard 12462011.4.4 Mechanical damage, other than broken strands, may notsignificantly affect the cable resistance. Close m

18、anual andvisual inspection is required to detect some types of mechani-cal damage.4.5 The test procedures in this specification should beperformed at a time interval established by the user to ensurethat defective grounding jumper assemblies are detected andremoved from service in a timely manner.4.

19、6 Retest the grounding jumper assembly after performingany maintenance, in order to ensure its integrity.5. Inspection of Grounding Jumper Assemblies5.1 Visual inspection shall be made of all grounding jumperassemblies prior to testing.5.1.1 If the following defects are evident, the groundingjumpers

20、 may be rejected without electrical testing:5.1.1.1 Cracked or broken ferrules and clamps,5.1.1.2 Exposed broken strands,5.1.1.3 Cut or badly mashed or flattened cable,5.1.1.4 Extensively damaged cable- covering material,5.1.1.5 Swollen cable jacket or soft spots, indicating inter-nal corrosion, and

21、5.1.1.6 Cable strands with a black deposit on them.5.1.2 Grounding jumper assemblies which are visually de-fective shall be removed from service and permanentlymarked, tagged or destroyed (if beyond repair) to preventre-use.5.1.3 Before the grounding jumper assembly can be placedback in service, it

22、must pass the inspection requirements in5.1.1, and the electrical requirements in Section 7.5.1.4 All physical connections should be checked for tight-ness with specified torque values.6. Cleaning and Measuring of Grounding JumperAssembly Prior to Electrical Testing6.1 Identify the cable gage (AWG)

23、and a make a precisemeasurement of the cable length. See Fig. 1.6.2 Thoroughly clean the jaws of the clamps with a stiffwire brush.6.3 Attach the grounding jumper assembly clamps firmly tothe test set.7. Electrical Requirements7.1 The user must select the test method with the desiredprecision and re

24、peatability. The test instrument should besufficiently accurate to detect at least a one foot or less changein cable length to ensure that the cable meets requirements.7.2 Each method must take into account a precise cableresistance per foot and the length of the cable being tested.7.3 Electrical te

25、sts relative to this standard are:7.3.1 DC resistance measurements,7.3.2 AC impedance measurements, and7.3.3 Temperature rise measurements (supplementarymethod).7.4 DC Resistance or AC Impedance MethodEquipmentrequired includes:7.4.1 A minimum 10 A dc source controllable to 5 % ofoutput current, sho

26、rt circuit protected, or7.4.2 A minimum 10 A ac source controllable to 5 % ofoutput current, short circuit protected.7.4.3 Measuring method for measurements of cable lengthcalibrated in inches or centimeters.7.5 In-Service Electrical Resistance Pass/Fail CriteriaThe pass/fail criterion of a groundin

27、g jumper assembly isbased on the resistance value of the assembly (cable, ferrulesand clamps) which is higher than the established resistancevalue for new assemblies. This increase in resistance accountsfor manufacturing tolerance and the expected normal deterio-ration of the assembly due to aging,

28、contamination andcorrosion, particularly in the contact areas of the cable ferrulesand clamps. The allowable increase in resistance is such as topermit the grounding jumper assembly to perform safelyduring electrical faults. The grounding jumper assembly, whensubjected to its rated maximum fault cur

29、rent and duration, mustwithstand the fault without its components separating, butsome heat damage and discoloration is acceptable. The elec-trical resistance value for the pass/fail criterion is made up oftwo parts (Fig. 1), the cable resistance and the resistance of theFIG. 1 Resistance and Impedan

30、ce of Copper Grounding JumperAssembliesY = resistance of clamps, ferrule and portions of the cableinside the ferrule, mL = cable length expressed in feet (ferrule to ferrule mea-surement to the nearest inch, not including shroudedportion of some ferrules which cover the cableinsulation), andR = cabl

31、e resistance from Table 1,m/ft.F2249 182two ends containing short cable sections, ferrules and clamps.When the grounding jumper assemblies are tested with a dcsource, the dc resistance of the assembly is used for the pass orfail purposes. With an ac source, the impedance of the cableand the impedanc

32、e of the ends (ferrules and clamps) are usedto determine if the grounding jumper fails or passes the test.7.5.1 Cable ResistanceCopper cables used as part of agrounding jumper assembly must be constructed in accordancewith Specifications B172 or B173 as specified in SpecificationF855. Four cable cla

33、sses are identified in Specification F855 asbeing acceptable cables for use in ground cable assemblies.They are Class H, Class I, Class K, and Class M. Class K cablehas proven to be a very popular cable class for use in groundcable assemblies. Table 1 provides the nominal resistancevalues for typica

34、l sizes of Class K cables used in groundingjumper assemblies. If the user is unable to determine thespecific class of cable used in a ground cable assembly, theresistance values in Table 1 are a reasonable approximation forall four cable classes. Cable resistance values for all four cableclasses are

35、 located in Appendix X1 through Appendix X4.7.5.1.1 The cable resistance can change with ambient tem-peratures. A 65.09C (69.16F) change in ambient tempera-tures will cause a 62 % change in the measurement ofresistance values. Table 1, and Tables X1.1, X2.1, X3.1, andX4.1 give cable resistance value

36、s for a practical range oftemperatures 5C, 20C, and 35C (41F, 68F, and 95F).Resistance values for different temperature values can becomputed using Eq 1, where R20is the cable resistance per footin m/ft at 20C, RT2is the cable resistance at the desiredtemperature T2, and T2is the desired temperature

37、 in C.RT25 R20* 1 1 0.00393 * T22 20!# mft (1)7.5.1.2 Results from the ASTM Round Robin Tests haveshown that an increase in cable resistance at a given tempera-ture due to a combination of manufacturing tolerance and agingeffects should not exceed 5 %. Therefore, the maximumacceptable resistance in

38、cables used in temporary protectivegrounding jumpers should be equal to or less than 1.05 RL,when R = cable resistance in m/ft from Table 1, and L = cablelength in feet.7.5.2 Resistance and Impedance of Copper GroundingJumper AssembliesSee Table 1, X1.1, X2.1, X3.1, or X4.1.7.5.2.1 Maximum Resistanc

39、e of the Grounding Jumper As-sembly (Rm):Rm 5 1.05 RL12Y m (2)7.5.2.2 Maximum Impedance of the Grounding JumperAssembly (Zm):Zm 5 =1.05RL12Y!21XL!2m (3)where:X = reactance of the cable in m/ft.NOTE 1Values of X can be found in data books such as the StandardHandbook of Electrical Engineers.47.5.3 Te

40、sting with a DC SourceA dc source can be used todetermine the pass/fail value for a given grounding jumperassembly. The resistance value (R) obtained from such ameasurement should be compared with the calculated limitingmaximum resistance (Rm) using Eq 2 or it can be compared tothe resistance values

41、 in Tables X1.2, X2.2, X3.2, or X4.2. Thecalculated criterion for pass/fail is based on 2/0 cable fault testsconducted in Round Robin III (See Appendix X5). Theresistance of Y in the Rm (Eq 2) has been determined byconservative analysis of the data to be 0.16 m. This value isbelow the “fusing range”

42、 of cables that passed the fault tests.The value of Y = 0.16 m or 2Y = 0.32 m for all cable sizes.Therefore, the pass/fail resistance value is:Rm 5 1.05 RL10.32 m (4)NOTE 2Tables X1.2, X2.2, X3.2 and X4.2 were derived from Eq 4.7.5.4 Testing with an AC SourceWhen an ac source isused, it will determi

43、ne the grounding jumper assembly imped-ance (Z). This impedance is a function of the cable and the testelectrode spacing. For cable spacing of 12 in. or less, the cablereactance can be very low and the impedance value canapproach that of the cable resistance. The impedance (Z)obtained from such a me

44、asurement should be compared withthe calculated limiting maximum impedance (Zm) using Eq 3to determine if the grounding jumper assembly has passed orfailed the test. The pass/fail impedance value based on 2/0cable fault tests is:Zm 5 =1.05 RL10.32!21XL!2m (5)If multiple spacing of the cable is utili

45、zed in the test setup,the above equation becomes:Zm 5 =1.05 RL10.32!21X1L11X2L21XNLN!2m (6)NOTE 3AC testing measurements of grounding jumper assemblies aresusceptible to errors and inconsistent results due to induction in the cableif the cable is not laid out per the test method instructions. Differ

46、entinstruments require different configurations (see Fig. 2).NOTE 4AC testing measurements of grounding jumper assemblies aresusceptible to errors if metal is laid across the cable or the cable is laidacross a metal object, even if the metal object is buried, such as areinforcing bar embedded in a c

47、oncrete floor.8. Cleaning/Reconditioning of Grounding JumperAssembly after Electrical Testing8.1 For the readings which are high, additional cleaning andtightening of the assembly may restore its electrical integrity.8.2 Disassemble the grounding jumper assembly and thor-oughly clean the ferrule and

48、 clamp interface with isopropylalcohol and a stiff wire brush.8.3 Inspect all components during the disassembly andreassembly process.4Standard Handbook for Electrical EngineersThirteenth Edition by Fink commonly available with a minimum 312 or 412 digit meter.X6.2.1.3 Measuring Tape, optionalUsed i

49、f voltagescreening method is utilized; for measurements of cable lengthto the nearest inch or centimeter.X6.2.1.4 Non-contact Thermometer, infrared with digitalreadout (laser sighting recommended-observe normal eye pro-tection requirements when handling lasers). Check specificmanufacturers instruction book for emissivity setting for testTABLE X5.3 2/0 Copper Grounding Jumper Assemblies thatFailed the High Current Fault TestsTotal Length: A, C, BLength,ftCalculatedmActual mReadingPercentDifference6 0.48 1.72 2586 0.48 3.04 5337