ASTM F2249-2003 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临时接地跨接.pdf

《ASTM F2249-2003 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临时接地跨接.pdf》由会员分享，可在线阅读，更多相关《ASTM F2249-2003 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临时接地跨接.pdf（7页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: F 2249 03Standard 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 indicates the year ofor

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

3、trical 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 prote

4、c-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 this specification

5、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 responsibility of the u

6、ser of this standardto establish appropriate safety and health practices anddetermine the applicability of regulatory requirements prior touse.2. Referenced Documents2.1 ASTM Standards:B 193 Test Method for Resistivity of Electrical ConductorMaterials2F 855 Specifications for Temporary Grounding Sys

7、tems ToBe Used on De-energized Electric Power Lines AndEquipment32.2 IEEE Standards:4IEEE 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 Standard:3.1.1

8、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 spec

9、ified 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 anobjective mea

10、ns 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 fault condi-tion

11、s. 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 resistance. Close man

12、ual 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.4.6

13、Retest the grounding jumper assembly after performingany maintenance, in order to ensure its integrity.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.Curr

14、ent edition approved Feb. 10, 2003. Published April 2003.2Annual Book of ASTM Standards, Vol 02.03.3Annual Book of ASTM Standards, Vol 10.03.4Available from the Institute of Electrical and Electronics Engineers, Inc. (IEEE)1828 L St., NW, Suite 1202, Washington, CD 200365104.1Copyright ASTM Internat

15、ional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 reject

16、ed 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, and5.1.1.6 Cable

17、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 must pass the

18、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) and a make a p

19、recisemeasurement 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 repeatability. T

20、he 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 tests relative t

21、o 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, short circuit pro

22、tected, 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 centimetres.7.5 In-Service Electrical Resistance Pass/Fail CriteriaThe pass/fail criterion of a grounding jumper assem

23、bly is basedon the resistance value of the assembly (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

24、 the contact areasof the cable ferrules and clamps. 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

25、without itscomponents separating, but some heat 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 g

26、roundingjumper assemblies 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 C

27、able ResistanceTable 1 provides 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 resi

28、stance values for a practical 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 prot

29、ective grounding jumpers 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.TABLE 1 Copper Cable Resistance, mVAGroundingCable SizeResistance, mV/ftat 5C (41F)Resistan

30、ce, 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 0.0461 0.0490 0.0519AValues are calculated from data in Test Method B 193.FIG. 1 Resistance and Impedance of Copper Grounding JumperAssembliesY = resistance of clamps, ferrule

31、 and portions of the cableinside the ferrule, mVL = cable length expressed in feet (ferrule to ferrule mea-surement to the nearest inch, not including shroudedportion of some ferrules which cover the cable insula-tion), andR = cable resistance from Table 1, mV.F22490327.5.2.1 Maximum Resistance of t

32、he Grounding Jumper As-sembly (Rm):Rm 5 1.05 RL 1 2Y (1)7.5.2.2 Maximum Impedance of the Grounding JumperAssembly (Zm):Zm 5 =1.05RL 1 2Y!21 XL!2(2)where:X = reactance of the cable in mV.NOTE 1Values of X can be found in data books such as the StandardHandbook of Electrical Engineers.57.5.3 Testing w

33、ith 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 1 or it can be compared tothe resistance values in Tab

34、le 2. The calculated criterion forpass/fail is based on 2/0 cable fault tests conducted in RoundRobin III (See Appendix 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 faul

35、t tests. The value of Y = 0.16 mV or 2Y =0.32 mV for all cable sizes. Therefore, the pass/fail resistancevalue 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). Thi

36、s 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 measurement should be compared withthe calculated limi

37、ting maximum impedance (Zm) using Eq 2to 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 =1.05RL 1 0.32!21 XL!2(4)If multiple spacings of the cable are utilized in the test setup,the above equation becomes:Z

38、m 5 =1.05RL 1 0.32!21 X1L11 X2L2. 1 XNLN!2(5)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. Differentinstruments require different configuration

39、s (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 concrete floor.8. Cleaning/Reconditioning of Gr

40、ounding JumperAssembly After Electrical Testing8.1 For the readings which are high, additional cleaning andtightening of the assembly may restore its electrical integrity.5Standard Handbook for Electrical EngineersThirteenth Edition by Fink commonly available with a minimum 312 or 412 digit meter.X2

41、.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 digitalreadout (laser sighting recommended-observe normal eye pro-tection requirements when handling lasers).

42、Check specificmanufacturers instruction book for emissivity setting for testTABLE X1.3 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 1.26 971

43、0 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,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

44、 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 3.19Avg = 2.25 mVF2249036area background. WarningBackground temperature can in-fluence the temperature readings.X2.2.1.5 Adequate Hand Protection, defective cables maydevelop hot spot

45、s during testing.X2.3 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 anddead front g

46、rounding assemblies.)X2.3.3 To minimize the impedance effect of AC 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 clamps to the

47、manufacturersspecifications (typically 25 ft/lb).X2.4.2 Apply the rated current, 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 t

48、hermometer 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 te

49、mperature 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 temperaturevariance and acceptance values should be based on userexperience. Small-mass grounding clamps composed of bronze(ball and socket style) will have a higher temperature 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