Документы

ASTM International

Standard Specifications for Temporary Protective Grounds to Be Used on De-energized Electric Power Lines and Equipment
 N F855

Annotation

These specifications cover the equipment making up the temporary grounding system used on de-energized electric power lines, electric supply stations, and equipment.

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.

The uses and maintenance of this equipment are beyond the scope of these specifications.

Each of the four parts is an entity of itself, but is listed as a part of the system for completeness and clarification.

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 X3.

Currents presented in Table 2 are based upon the values from EPRI Project RP2446 Computer Program RTGC "A Desktop Computer Program for Calculating Rating of Temporary Grounding Cables" and are to be used in situations involving an asymmetry value greater then 20 % (X/R >1.8), see Appendix X4.

NOTE 1—Table 1 represents the clamp and assembly ratings that existed prior to this revision. Table 2 represents new ratings now required for high X/R situations.

See Appendix X3 and Appendix X4 for a discussion of these topics.

The values stated in Newton-Meter units are to be regarded as the standard. The values in parentheses are the inch-pound units.