DIN EN 61472:2014-02

This International Standard describes a method for calculating the minimum approach distances for live working, at maximum voltages between 72,5 kV and 800 kV. This standard addresses system overvoltages and the working air distances or tool insulation between parts and/or workers at different electric potentials. The required withstand voltage and minimum approach distances calculated by the method described in this standard are evaluated taking into consideration the following: - workers are trained for, and skilled in, working in the live working zone; - the anticipated overvoltages shall not exceed the value selected for the determination of the required minimum approach distance; - transient overvoltages are the determining overvoltages; - tool insulation has no continuous film of moisture or measurable contamination present on the surface; - no lightning is seen or heard within 10 km of the work site; - allowance is made for the effect of conducting components of tools; - the effect of altitude, insulators in the gap, etcetera, on the electric strength is taken into consideration. For conditions other than the above, the evaluation of the minimum approach distances can require specific data, derived by other calculation or obtained from additional laboratory investigations on the actual situation. Compared with DIN EN 61472 (VDE 0682-100):2005-07, Corrigendum 1 to DIN EN 61472 (VDE 0682-100, Corrigendum 1):2005-12 and Corrigendum 2 to DIN EN 61472 (VDE 0682-100, Corrigendum 5):2008-11, the following modifications have been made: a) clarification of the scope; b) review of the definitions; c) clarification of the methodology of determining whether live working is permissible and the calculation of the minimum approach distances; d) modification of the basic equation for calculation of the minimum approach distance; e) introduction of Table 1 for altitude correction factor simplification k_a; f) introduction of criteria in presence of composite insulator and clarification on the use of insulator factor k_i; g) review of the informative Annex F on the influence of floating conductive objects on the dielectric strength; h) review of informative Annex G on live working near contaminated, damaged or moist insulation. The responsible committee is DKE/K 214 "Ausrüstung und Geräte zum Arbeiten unter Spannung" ("Equipment and tools for live working") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.