10-04-2017, 08:45 PM
The development of the equipment and systems sensitive to lightning electromagnetic impulse (LEMP) requires more efficient protection measures within a new lightning protection zones (LPZ) concept. effective selection and application of these measures should be based on a probabilistic approach which may contain procedures like:
-recognition of all kinds of lightning influence on the structure and its sensitive equipment;
-selection of protection measures in respect of highest value of risk component and LPZ concept
-assessment of lightning hazard involving structure features and protection measures efficiency;
The key-point in the analysis of lightning protection devices is the determination of the protection zone. The boundary element analysis of the protection zone of a metallic post, as one of the most commonly used lightning protection devices is the common method to determine the LPZ of the post. Protection against LEMP is based on the concept of LPZ,
the lightning protection zones, characterised by
significant changes of the LEMP severities compatible
with the immunity level of the internal systems.(LEMP:
lightning electromagnetic impulses).
The following
LPZ are defined for full LPM systems:
*outer zones:
- LPZ 0 = zone endangered by unattenuated lightning
magnetic and electric field and by surges up to full or
partial lightning current. This region is again divided into:
1)LPZ 0A endangered by direct lightning strikes, by surges
up to full lightning current and by full lightning field
2)LPZ 0B protected against direct lightning strikes but
endangered by surges up to partial lightning current and
by full magnetic field
inner zones (protected against direct lightning strikes):
- LPZ 1:Here the surges are limited by current sharing and
by SPD at the boundary; the lightning field can be
attenuated by spatial shielding;
- LPZ 2, N :In this region, the surges are further limited by current
sharing and SPD at the boundary; the lightning field is
usually attenuated by spatial shielding.
For moe, visit this pdf:
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