Minimum approach distances in hotline work a practical method for their determination

Abstract

The authors intend to establish, for each voltage value and not for each voltage bracket, two minimum approach distances for hot-line power transmission line maintenance which, as discussed in this paper, correspond to points, on two converging straight lines which cover virtually all clearances used in various countries and are highly consistent with the studies performed by the WG 10 of IEC/TC 78. It may be useful in practice to use one of these extreme clearances or some other intermediate value depending an the climate conditions; thus, for example, for relative humidity over 80% the maximum clearance distance would be taken: and for relative humidity under 20% the minimum clearance distance would be taken. It is likewise intended to separate the inadvertent movement distances and that these be taken into account as one of the parameters coming into the sum for all determinations of minimum approach distances, since said inadvertent movement dimensions are susceptible to variation with improvements in technology and work procedures. Furthermore, since they always come into the sum, one has to be careful that these inadvertent movement distances cannot be left out or added twice.