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Technical
Section 9
Dimensions
Section 10
Surge arresters
Protection against
lightning strikes and
overvoltages
4
Exposed equipment such as antennas, satellite dishes and cameras must be
protected from lightning strikes. Electronic equipment is also at risk, a direct strike
to external equipment often results in damage to connected internal equipment but
can also cause damage to unrelated equipment by flashovers in shared cable routes
or cabinets. In addition to this the British Standards for the protection of a structure
from a lightning strike and lightning surge protection devices are changing. Merlin
Gerin, has developed a comprehensive range of surge protection equipment. For
the protection of electrical installations and equipment from the effects of a direct
or indirect lightning strike and from the effects of overvoltages caused by effects
internal to the electrical system. The effectiveness of lightning protection is closely
related to the installation and choice of the surge arresters.
To ensure the protection of equipment connected to:
n
Low voltage networks
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Telecommunications networks
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Computer networks
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Certified coordination between the surge arrester and its disconnection circuit
breaker
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Protection against the nuisance tripping of “si” and “SiE” earth leakage protection
devices during a lightning strike
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Easy to implement and use
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Compatibility with all earthing systems (TT, TNS, TNC, IT)
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Technical and aesthetic consistency
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Compliance with standards
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Availability of products and services
PRF1/PRF 1 Master surge arresters
The Type 1 PRF1 surge arrester protects electrical installations against direct
lightning strikes. It is recommended for electrical installations in service sector
and industrial buildings, protected by a lightning conductor or by a meshed cage.
It is used to conduct a direct lightning current and is propagated through the live
conductors and the earth conductor. It must be installed with an upstream fuse
type or circuit breaker protection (disconnection) device whose breaking capacity
must be at least equal to the maximum prospective shortcircuit current at the
installation point.
PRD Draw-out surge arresters
PRD removable surge arresters enable the rapid replacement of damaged
cartridges.
Removable surge arresters with local indication (PRD 65r, PRD 40r) have remote
indication as well as the remote transfer of “cartridge to be replaced” information.
The Uc voltage depends on:
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The earthing system
n
The protection mode (MC/MD).
Each surge arrester in the range has a specific use:
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Incomer protection
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The PRD 65r is recommended for a very high risk level (highly exposed site)
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PRD 40r/PRD 40 are recommended for a high risk level
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The PRD 15 is recommended for a low risk
n
Level secondary protection: the PRD 8 ensures secondary protection of loads to
be protected and is placed in a cascading configuration with surge arresters at
the incomer end
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