IEC 62305-2:2010 pdf – Protection against lightning-Part 2: Risk management.
coordinated SPD system
SPDs properly selected, coordinated and installed to form a system intended to reduce failures of electrical and electronic systems
isolating interfaces
devices which are capable of reducing conducted surges on lines entering the LPZ
NOTE I Th., include isolifion Ir,nsfonn,rs wth serthed screen b.tweei, windings, metal-free fitir. optic cables and opto-isdators,
NOTE 2 Insulation withstand chac1erislics & these devices are suitable for thiS application intrinsically or via spo
lightning equipotential bonding
bonding to LPS of separated metallic parts. by direct conductive connections or via surge protective devices, to reduce potential differences caused by lightning current
zone 0
place in which an explosive atmosphere consisting of a mixture of air and flammable substances in the form of gas. vapour or mist is present continuously or for long periods or frequently
(IEC 60050-426:2008. 426-03-03, modIfied)151
zone 1
place in which an explosive atmosphere consisting of a mixture of air and flammable substances in the form of gas, vapour or mist is likely to occur in normal operation occasionally
(IEC 60050-426:2008, 426-03-04, modified )
zone 2
place in which an explosive atmosphere consisting of a mixture of air and flammable substances in the form of gas, vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only
NOTE I In this definition, the ward perslst means the total time for which the flammable atmosphere will esisi. Thi, will normally comprise the total of the duration of the rilesse, plus th, time taken tar th, flammable atmosphere to disperse after the release has stopped.
NOTE 2 lndicetione of tile frequency of the occurrence arid duration may be taken from codes relating to specific industries or applications.
(IEC 60050-426:2008. 426-03-05, modified)
zone 20
place in which an explosive atmosphere, in the form of a cloud of combustible dust in air, is present continuously, or for long periods, or frequently
(IEC 60079-10-2:2009. 6.2, modified)
4 Explanation of terms
4.1 Damage and loss
4.1.1 Source of damage
The lightning current is the primary source of damage. The following sources are distinguished by the point of stnke (see Table 1):
SI: flashestoa structure,
S2: flashes near a structure,
S3: flashes to a line,
S4; flashes near a line.
4.1.2 Types of damage
A lightning flash may cause damage depending on the charactenstics of the structure to be protected. Some of the most important characteristics are: type of construction, contents and application, type of service and protection measures provided.
For practical applications of this risk assessment, it is useful to distinguish between three basic types of damage which can appear as the consequence of lightning flashes, They are as follows (see Table 1):
Dl: injury to living beings by e4ectrlc shock. D2: physical damage, D3 failure of electrical and electronic systems.
The damage to a structure due to lightning may be limited to a part of the structure or may extend to the entire structure. It may also Involve surrounding structures or the environment (e.g. chemical or radioactive emissions).
4,1.3 Types of loss
Each type of damage, alone or in combination with others, may produce a different consequential loss in the structure to be protected. The type of loss that may appear, depends on the characteristics of the structure itself and its content. The following types of loss shall be taken into account (see Table 1):
Li: loss of human life (Including permanent injury);
L2: loss of service to the public;
L3: loss of cultural heritage:
L4: loss of economic value (structure, content, and loss of activity).
Component related to injury to living beings caused by electric shock due to touchvoltage inside the structure.Loss of type L1 and, in the case of agricultural properties,losses of type L4 with possible loss of animals could also occur.
Component related to physical damage (fire or explosion triggered by dangeroussparking between external installation and metallic parts generally at the entrance pointof the line into the structure) due to lightning current transmitted through or alongincoming lines.All types of loss (L1,L2,L3,L4) may occur.