centre of attention
Recently we have seen an increase in
disruption to data centre services due
to lightning strikes. The nature of loss
in data centres is not only through
damage to sensitive equipment, but
also the loss of productivity due to
disruption in service. The degradation
of equipment also leads to loss of
time in replacement of parts.
Currently in an effort to protect
buildings, more than 100 published
lightning protection codes and
standards are in use by various
agencies within countries. In
the last two decades, significant
information has been gathered and
the International Electro-technical
Commission (IEC) has made final
an authoritative and comprehensive
lightning protection standard in four
parts, known as the IEC 62305 Series.
The dangers of a strike
Before exploring methods of
protection, it is important to understand
the nature of damage that is likely to
disrupt or damage the functioning of
today’s data centre. The impact of
lightning normally causes damage to
the equipment in three ways; firstly
by direct strike to the installation,
secondly by direct strike on to an
overhead line or the ground nearby,
and lastly by cloud to cloud strike. A
direct strike to the installation tends
to be protected by the presence of a
standard lightning protection system;
it is the latter two situations that cause
indirect lightning electromagnetic
impulses that prove disastrous.
When there is a strike at a nearby
ground, or cloud to cloud, a series of
electrical surges are generated and
picked up by the metallic conductors
that enter the building. This conductor
could be a utility cable, telecom cable
or any other cable that supplies power
or data to an external device on the
building perimeter or rooftop. This
could be the external perimeter lighting,
camera, ac plant or even a fire alarm
device. The transient surge ripples
through the power distribution system
and damages almost all the electronic
components in the installation.
Engineering solutions
Firstly it would be sensible to reduce
the risk by locating the data centre
in an area with a low thunderstorm
rate, by referring to the global
flash density map. Unfortunately in
most instances this is not possible.
Given there is currently no way of
changing natural weather conditions,
the next step would be to carry out
a risk assessment of the centre.
The IEC Lightning Protection
Code IEC62305 Part 2 is used to
determine the classification of the
lightning protection level required,
with class I being the greatest.
Some properties are more at risk
than others, and factors such as the
size and height of the building can
affect this. Here four main aspects
of lightning risks are explored, with
the highest being loss of human life.
Lightning protection specialists can
carry out early stage assessments
and will produce full reports, findings,
and recommendations.
Next in prevention preparations
it is standard practice for engineers
to design the air termination by
following the rolling sphere, mesh
and protection angle methods in
accordance with IEC 62305 Part 3.
This aims to capture the lightning
discharge current and enables it
to flow to the earth harmlessly,
ensuring that the building is
now safe ‘for life and property’.
Unfortunately though this does not
guarantee safety for the electronic
equipment within the building.
It goes without saying that
electronic systems are vital in data
centres. The reduction of risk of
permanent failure and damage to
electrical and electronic equipment is
covered in BS EN62305 Part 4. In
a shielded environment the correct
coordination and installation of surge
protection devices will be advised by
your appointed lightning protection
specialist. This will ensure that sensitive
electronic equipment can be protected
from damage and continue to operate
in the event of a lightning strike.
Moving forward
For new data centres considering
lightning protection, plans must
be made early in the design stage
to achieve cost effectiveness and
sufficient protection. This will allow
for maximum use of the natural
components of the structure and
provide a better choice for the cabling
layout and equipment location.
For those existing structures the
cost of lightning protection measures
tends to be higher. Although budget
restrictions may raise doubt as to
the necessity of protection from
natural elements, the risks must be
considered and lightning attacks
treated with caution. Ultimately
the consequences of losing both
equipment and time could be
catastrophic to your business.
Our top three tips to ensure
proper protection are as follows:
Ensure provisions are defined by a
lightning protection expert.
Manage effective coordination
and communication between the
different experts involved in the
building construction from the
concept stage of the project.
Maintain and regularly check the
lightning protection system as per
the recommendations.
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