ASTM F2249-2003(2009) 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: F 2249 03 (Reapproved 2009)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 F 2249; the number immediately following the designation indic

2、ates 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 i

3、nspection 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 th

4、e temporary protec-tive grounding of de-energized circuits.1.3 Manufacturing specifications for these groundingjumper assemblies are in Specifications F 855.1.4 The application, care, use, and maintenance of thisequipment are beyond the scope of this specification.1.5 Units of measurement used in th

5、is 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 respon

6、sibility 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:2B 193 Test Method for Resistivity of Electrical ConductorMaterialsF 855 Specifications for Tempor

7、ary Protective Grounds toBe Used 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 T

8、his Standard: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 circui

9、t current 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 prov

10、ide anobjective 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 electric

11、al fault 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 re

12、sistance. 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 Pro

13、tective Equipment for Workers and is the direct responsibility ofSubcommittee F18.45 on Mechanical Apparatus.Current edition approved April 1, 2009. Published April 2009. Originallyapproved in 2003. Last previous edition approved in 2003 as F 2249-03.2For referenced ASTM standards, visit the ASTM we

14、bsite, 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 St., NW, Suite 1202,

15、Washington, CD 200365104.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.that defective grounding jumper assemblies are detected andremoved from service in a timely manner.4.6 Retest the grounding jumper assembly after performingany

16、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 testing:5.1.1.1 Cracked

17、 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 deposit on them.5.1.2 Gr

18、ounding 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 in5.1.1, and the elec

19、trical 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 cable length. See Fi

20、g. 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 should besufficiently accu

21、rate 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:7.3.1 DC resistance measu

22、rements,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 minimum 10 A ac source cont

23、rollable 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 is basedon the resistance value of the as

24、sembly (cable, ferrules andclamps) which is higher than the established resistance valuefor new assemblies. This increase in resistance accounts for theexpected normal deterioration of the assembly due to aging,contamination and corrosion, particularly in the contact areasof the cable ferrules and c

25、lamps. The allowable increase inresistance is such as to permit the grounding jumper assemblyto perform safely during electrical faults. The groundingjumper assembly, when subjected to its rated maximum faultcurrent and duration, must withstand the fault without itscomponents separating, but some he

26、at damage and discolora-tion is acceptable. The electrical resistance value for thepass/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 assemblies are tested with a d

27、c 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 provides resistance va

28、luesfor 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 practical range of temper

29、a-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 should be equal orle

30、ss 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 RL 1 2Y (1)7.5.2.2 Maximum Impedance of the Grounding Jumper

31、Assembly (Zm):Zm 5 =1.05RL 1 2Y!21 XL!2(2)where:X = reactance of the cable in mV.TABLE 1 Copper Cable Resistance, mVAGroundingCable SizeResistance, mV/ftat 5C (41F)Resistance, mV/ftat 20C (68F)Resistance, mV/ftat 35C (95F)#2 0.1471 0.1563 0.16551/0 0.0924 0.0983 0.10402/0 0.0733 0.0779 0.08254/0 0.0

32、461 0.0490 0.0519AValues are calculated from data in Test Method B 193.F 2249 03 (2009)2NOTE 1Values of X can be found in data books such as the StandardHandbook of Electrical Engineers.47.5.3 Testing with a DC SourceAdc source can be used todetermine the pass/fail value for a given grounding jumper

33、assembly. 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 in RoundRob

34、in III (SeeAppendix X1). The resistance of Y in the Rm (Eq1) has been determined by conservative analysis of the data tobe 0.16 mV. This value is below the “fusing range” of cablesthat passed the fault tests. The value of Y = 0.16 mV or 2Y =0.32 mV for all cable sizes. Therefore, the pass/fail resis

35、tancevalue is:Rm 5 1.05 RL 1 0.32 mV (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 in. or

36、 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 orfai

37、led the test. The pass/fail impedance value based on 2/0cable fault tests is:Zm 5 =1.05RL 1 0.32!21 XL!2(4)If multiple spacings of the cable are utilized in the test setup,the above equation becomes:Zm 5 =1.05RL 1 0.32!21 X1L11 X2L2. 1 XNLN!2(5)NOTE 3AC testing measurements of grounding jumper assem

38、blies aresusceptible to errors and inconsistent results due to induction in the cable4Standard Handbook for Electrical 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 measur

39、ements of cable lengthto the nearest inch or centimetre.X2.2.1.4 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 X1.3

40、 2/0 Copper Grounding Jumper Assemblies thatFailed the High Current Fault TestsTotal Length: A, C, BLength,ftCalculatedmVActual mVReadingPercentDifference6 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

41、198Middle Section: CLength2,ftCalculatedmVActual mVReadingPercentDifference4 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

42、 of the Test Samples: 1.153 to 3.19Avg=2.25mVF 2249 03 (2009)7area background. WarningBackground temperature can in-fluence the temperature readings.X2.2.1.5 Adequate Hand Protection, defective cables maydevelop hot spots during testing.X2.3 Test Set-upX2.3.1 Test should be performed indoors if poss

43、ible 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 anddead front grounding assemblies.)X2.3.3 To minimize the impedance effect ofAC testing, it is

44、recommended 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 clamps to the manufacturersspecifications (typically 25 ft/lb).X2.4.2 Apply the rated current,

45、per Specifications F 855Table 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 theinfrared thermometer held 12 in. from the ground assembly. (Inthe case of deadfront undergr

46、ound 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 assembl

47、y after the 3 min test.Allcomponents should read within 15F (or 8.3C) of each other.Large-mass ground components will have less temperaturevariance and acceptance values should be based on userexperience. Small-mass grounding clamps composed of bronze(ball and socket style) will have a higher temper

48、ature varianceand acceptance values should be based on user experience.X2.4.4 Should any part of the grounding jumper assemblyexceed the temperature of another part of the assembly by 15For more, it shall be disassembled, inspected, repaired andreassembled. The repaired assembly shall be retested.NO

49、TE X2.1AC testing measurements of grounding jumper assemblyare susceptible to errors and inconsistent results due to induction if thecable is not properly laid out.NOTE X2.2AC testing measurements of grounding jumper assemblyare susceptible 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 asreinforcing bar embedded in a concrete floor.NOTE X2.3If the voltage drop measured across the grounding jumperassembly exceeds the allowable in the AC Test Tables, the test n