IEC 61472-2:2021 pdf free download Live working – Minimum approach distances – Part 2: Method of determination of the electrical component distance for AC systems from 1,0 kV to 72,5 kV
1 Scope
This part of EC 61472 specifies a method for determining the electrical component of theminimum approach distances for live working, for AC systems 1 kV up to and including 72,5 kV.
This document addresses system overvoltages ‘and the working air distances betweenequipment and/or workers at different potentials.
The withstand voltage and minimum approach distances determined by the method describedin this document can be used only if the following working conditions prevail:
workers are trained for，and skilled in， working live lines or close to live conductors orequipment;
the operating conditions are adjusted so that the statistical overvoltage does not exceed thevalue selected for the determination of the required withstand voltage;
transient overvoltages are the determining overvoltages;
tool insulation has no continuous film of moisture present on the surface;no lightning is observed within 10 km of the work site;
– allowance is made for the effect of the conducting components of tools.
NOTEIn some countries，special procedures have been developed to permit live working with surface moisture ontools at distribution voltages (below’50 kv).
2Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
lSO and lEC maintain terminological databases for use in standardization at the followingaddresses:
.lEC Electropedia: available at http://www.electropedia.orgl
. Iso Online browsing platform: available at http://www.iso.orgl/obp
3.1
highest voltage of a systemUs
highest value of operating voltage (phase-to-phase voltage) which occurs under normaloperating conditions at any time and any point in the system
Note 1 to entry: Transient overvoltages and permanent induction from adjacent lines are not taken into account inthe calculationformula
3.2
transient overvoltage
short duration overvoltage of a few milliseconds or less, oscillatory or non-oscillatory, usually highly damped
[SOURCE: IEC 60050-614:2016, 614-03-14]
3.3
nominal system voltage
suitable approximate value of voltage used to designate or identify a system
[SOURCE: IEC 60038:2009, 3.1]
3.4
per unit statistical overvoltage phase-to-earth
u e2
phase-to-earth per unit overvoltage that has a 2 % probability of being exceeded
3.5
per unit statistical overvoltage phase-to-phase
u p2
per unit overvoltage that has a 2 % probability of being exceeded
3.6
statistical overvoltage
U 2
overvoltage that has a 2 % probability of being exceeded
3.7
minimum approach distance
D A
minimum electrical and ergonomic distance in air to be maintained between any part of the body of a worker, or any conductive tool being directly handled, and any live conductors or equipment at different potentials
IEC 61472-2:2021 pdf free download
