ASTM F2249-2003(2015) Standard Specification for In-Service Test Methods for Temporary Grounding Jumper Assemblies Used on De-Energized Electric Power Lines and Equipment《断电电源线和设备用.pdf

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1、Designation: F2249 03 (Reapproved 2015)Standard 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 indicat

2、es the year oforiginal 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 ins

3、pection andelectrical 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

4、temporary protec-tive 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

5、specification are 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 responsib

6、ility of the user of this standardto establish appropriate safety and health practices anddetermine the applicability of regulatory requirements prior touse.2. Referenced Documents2.1 ASTM Standards:2B193 Test Method for Resistivity of Electrical ConductorMaterialsF855 Specifications for Temporary P

7、rotective Grounds to BeUsed on De-energized Electric Power Lines and Equip-ment2.2 IEEE Standards:3IEEE Standard 801986 IEEE Guide for Safety in ACSubstation GroundingIEEE Standard 10481990 IEEE Guide for the ProtectiveGrounding of Power Lines3. Terminology3.1 Definitions of Terms Specific to This S

8、tandard:3.1.1 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 cur

9、rent fora specified duration (time).4. Significance 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 a

10、nobjective means of determining if a grounding 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 fa

11、ult condi-tions. Guidelines for use in the determination of these condi-tions are beyond the scope of this specification and can befound in such standards as IEEE Standard 801986 and IEEEStandard 10481990.4.4 Mechanical damage, other than broken strands, may notsignificantly affect the cable resista

12、nce. Close manual 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 ensure1This specification is under the jurisdiction of ASTM Committee F18 onElectrical Protecti

13、ve Equipment for Workers and is the direct responsibility ofSubcommittee F18.45 on Mechanical Apparatus.Current edition approved May 1, 2015. Published July 2015. Originally approvedin 2003. Last previous edition approved in 2009 as F2249-03(2009). DOI:10.1520/F2249-03R15.2For referenced ASTM standa

14、rds, 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 Summary page onthe ASTM website.3Available from the Institute of Electrical and Electronics Engineers, Inc. (IEEE)1828 L

15、 St., NW, Suite 1202, Washington, CD 200365104.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1that defective grounding jumper assemblies are detected andremoved from service in a timely manner.4.6 Retest the grounding jumper assembly

16、 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 may be rejected without electrical te

17、sting: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, and5.1.1.6 Cable strands with a black dep

18、osit 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 must pass the inspection requirements

19、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) and a make a precisemeasurement of the

20、 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 repeatability. The test instrument shoul

21、d 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 tests relative to this standard are:7.3.

22、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, short circuit protected, or7.4.2 A minimu

23、m 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 centimetres.7.5 In-Service Electrical Resistance Pass/Fail CriteriaThe pass/fail criterion of a grounding jumper assembly isbased on the resis

24、tance value of the assembly (cable, ferrulesand clamps) which is higher than the established resistancevalue for new assemblies. This increase in resistance accountsfor the expected normal deterioration of the assembly due toaging, contamination and corrosion, particularly in the contactareas of the

25、 cable ferrules and clamps. The allowable increasein resistance is such as to permit the grounding jumperassembly to perform safely during electrical faults. Thegrounding jumper assembly, when subjected to its rated maxi-mum fault current and duration, must withstand the faultwithout its components

26、separating, but some heat damage anddiscoloration is acceptable. The electrical resistance value forthe pass/fail criterion is made up of two parts (Fig. 1), the cableresistance and the resistance of the two ends containing shortcable sections, ferrules and clamps. When the groundingjumper assemblie

27、s are tested with a dc source, the dc resistanceof the assembly is used for the pass or fail purposes. With anac source, the impedance of the cable and the impedance of theends (ferrules and clamps) are used to determine if thegrounding jumper fails or passes the test.7.5.1 Cable ResistanceTable 1 p

28、rovides resistance valuesfor various sizes of cables used in grounding jumper assem-blies. The cable resistance can change with ambient tempera-tures. A 69F change in ambient temperatures will cause a62 % change in the measurement of resistance values. Table 1gives cable resistance values for a prac

29、tical range of tempera-tures (41, 68, and 95F). Results from the ASTM Round RobinTests have shown that an increase in cable resistance at a giventemperature due to aging effects should not exceed 5 %.Therefore, the maximum acceptable resistance in cables usedin temporary protective grounding jumpers

30、 should be equal orless than 1.05 RL, when R = cable resistance from Table 1, andL = cable length in feet.7.5.2 Resistance and Impedance of Copper GroundingJumper AssembliesSee Table 1.7.5.2.1 Maximum Resistance of the Grounding Jumper As-sembly (Rm):Rm 5 1.05 RL12Y (1)7.5.2.2 Maximum Impedance of t

31、he Grounding JumperAssembly (Zm):Zm 5 =1.05RL12Y!21XL!2(2)where:X = reactance of the cable in m.NOTE 1Values of X can be found in data books such as the StandardTABLE 1 Copper Cable Resistance, mAGroundingCable SizeResistance, m/ftat 5C (41F)Resistance, m/ftat 20C (68F)Resistance, m/ftat 35C (95F)#2

32、 0.1471 0.1563 0.16551/0 0.0924 0.0983 0.10402/0 0.0733 0.0779 0.08254/0 0.0461 0.0490 0.0519AValues are calculated from data in Test Method B193.F2249 03 (2015)2Handbook of Electrical Engineers.47.5.3 Testing with a DC SourceA dc source can be used todetermine the pass/fail value for a given ground

33、ing jumperassembly. The resistance value (R) obtained from such ameasurement should be compared with the calculated limitingmaximum resistance (Rm) using Eq 1 or it can be compared tothe resistance values in Table 2. The calculated criterion forpass/fail is based on 2/0 cable fault tests conducted i

34、n RoundRobin III (See Appendix X1). The resistance of Y in the Rm(Eq 1) has been determined by conservative analysis of the datato be 0.16 m. This value is below the “fusing range” of cablesthat passed the fault tests. The value of Y = 0.16 m or 2 Y =0.32 m for all cable sizes. Therefore, the pass/f

35、ail resistancevalue is:Rm 5 1.05 RL10.32 m (3)NOTE 2Table 2 was derived from Eq 3.7.5.4 Testing With an AC SourceWhen an ac source isused, it will determine the grounding jumper assembly imped-ance (Z). This impedance is a function of the cable and the testelectrode spacing. For cable spacing of 12

36、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 measurement should be compared withthe calculated limiting maximum impedance (Zm) using Eq 2to determine if the grounding jumper assembly has passed

37、 orfailed the test. The pass/fail impedance value based on 2/0cable fault tests is:Zm 5 =1.05RL10.32!21XL!2(4)If multiple spacings of the cable are utilized in the test setup,the above equation becomes:Zm 5 =1.05RL10.32!21X1L11X2L21XNLN!2(5)NOTE 3AC testing measurements of grounding jumper assemblie

38、s aresusceptible to errors and inconsistent results due to induction in the cableif the cable is not laid out per the test method instructions. Differentinstruments require different configurations (see Fig. 2).NOTE 4AC testing measurements of grounding jumper assemblies are4Standard Handbook for El

39、ectrical EngineersThirteenth Edition by Fink commonly available with a minimum 312 or 412 digit meter.X2.2.1.3 Measuring Tape, optionalUsed if voltagescreening method is utilized; for measurements of cable lengthto the nearest inch or centimetre.X2.2.1.4 Non-contact Thermometer, infrared with digita

40、lreadout (laser sighting recommended-observe normal eye pro-tection requirements when handling lasers). Check specificmanufacturers instruction book for emissivity setting for testarea background. WarningBackground temperature can in-fluence the temperature readings.X2.2.1.5 Adequate Hand Protection

41、, defective cables maydevelop hot spots during testing.TABLE X1.2 2/0 Copper Grounding Jumper Assemblies thatPassed the High Current Fault Tests with Some FusingTotal Length: A, C, BLength,ftCalculatedmActual mReadingPercentDifference6 0.48 2.04 3258 0.64 0.94 4710 0.8 0.83 3.310 0.8 0.83 3.810 0.8

42、0.83 4.310 0.8 0.83 4.410 0.8 0.83 4.312 0.96 2.04 112.515 1.2 1.23 2.330 2.4 2.5 4.235 2.8 8.35 198Middle Section: CLength2,ftCalculatedmActual mReadingPercentDifference4 0.32 0.42 31.36 0.48 0.486 1.38 0.64 0.645 0.88 0.64 0.646 0.98 0.64 0.657 1.98 0.64 0.647 1.18 0.64 0.652 1.910 0.8 0.837 4.613

43、 1.04 1.084 4.228 2.24 2.31 3.133 2.64 7.53 185.2Ends: A and B(a) Total Range: 0.07 to 1.486(b) Fusing Range: 0.353 to 1.486The high end No. (1.486) could be in the fusing-failurerange, so new fusing range is 0.353 to 0.77Avg = 0.56 m (0.407 m for Ontario Hydro)TABLE X1.3 2/0 Copper Grounding Jumper

44、 Assemblies thatFailed the High Current Fault TestsTotal Length: A, C, BLength,ftCalculatedmActual mReadingPercentDifference6 0.48 1.72 2586 0.48 3.04 5337 0.56 1.47 1628 0.64 1.26 9710 0.8 3.55 34410 0.8 1.17 4613 1.04 7.92 66219 1.52 1.59 4.319 1.52 2.2 4535 2.8 8.35 198Middle Section: CLength2,ft

45、CalculatedmActual mReadingPercentDifference4 0.32 0.39 21.94 0.32 0.391 22.25 0.4 1.198 1996 0.48 0.598 24.68 0.64 0.69 7.88 0.64 0.754 17.811 0.88 0.965 9.717 1.36 1.234 -9.317 1.36 1.663 22.333 2.64 7.53 185Ends: A and B(a) Total Range: 0.14 to 3.19(b) Failure Range of the Test Samples: 1.153 to 3

46、.19Avg = 2.25 mF2249 03 (2015)6X2.3 Test Set-upX2.3.1 Test should be performed indoors if possible or outof direct sunlight.X2.3.2 For best accuracy, grounding jumper assembly tem-perature should be allowed to reach equilibrium with the testenvironment. (This is essential for large mass connectors a

47、nddead front grounding assemblies.)X2.3.3 To minimize the impedance effect ofAC testing, it isrecommended that the grounding jumper assembly under testbe laid out in a tight parallel configuration.X2.4 Test ProcedureX2.4.1 Connect the grounding jumper assembly to the highcurrent source. Torque the c

48、lamps to the manufacturersspecifications (typically 25 ft/lb).X2.4.2 Apply the rated current, per Specifications F855Table 5, for 3 min (see Note X2.3). Immediately after the 3min, reduce the current to zero and turn off the current source.Scan the entire ground assembly, including the cable, with t

49、heinfrared thermometer held 12 in. from the ground assembly. (Inthe case of deadfront underground assemblies, the elbowshould be removed from the feedthru and the temperature ofboth the elbow and feedthru bushings current path measured.)X2.4.3 The pass/fail criteria of a ground jumper assembly isbased on the temperature variance (differential) of any com-ponents of the ground jumper assembly after the 3 min test.Allcomponents should read within 15F (or 8.3C) of each other.Large-mass ground components will have less tempe