ASTM F855-2017 断电状态的电源线和设备用临时保护性接地规格 Standard Specifications for Temporary Protective Grounds to Be Used on De-energized Electric Power Lines and Equipment

1.1 These specifications cover the equipment making up the temporary grounding system used on de-energized electric power lines, electric supply stations, and equipment. 1.2 It is common practice for the users of protective grounding equipment to prepare complete instructions and regulations to govern in detail the correct use and maintenance of such equipment. 1.3 The uses and maintenance of this equipment are beyond the scope of these specifications. 1.4 These specifications for a system of protective grounding utilizing copper cables are covered in four parts, as follows:           Sections Clamps for Temporary Protective Grounds   4 – 16 Ferrules for Temporary Protective Grounds   17 – 30 Cables for Temporary Protective Grounds   31 – 39 Protective Grounds (Complete Assembly With Clamps, Ferrules,   and Cable)   40 – 52 1.5 Each of the four parts is an entity of itself, but is listed as a part of the system for completeness and clarification. 1.6 Currents presented in Table 1 are based upon cable melting times, as determined from equations by I. M. Onderdonk and are to used in situations involving an asymmetry value less than 20 % (X/R ≤ 1.8). See Appendix X1. (A) Withstand and ultimate short circuit properties are based on performance with surges not exceeding 20 % asymmetry factor (see 9.1 and 12.3.4.2).(B) Yield shall mean no permanent deformation such that the clamp cannot be reused throughout its entire range of application.(C) Ultimate rating represents a symmetrical current which the assembly or individual components shall carry for the specified time.(D) Ultimate values are based upon application of Onderdonk's equation to 98 % of nominal circular mil area allowed by Specifications B172 and B173. Note 1: TPG testing is done on com