Lightning and transient overvoltage
damage
| |
|
 |
| Today's communications
and IT systems rely heavily on sophisticated
electronic equipment and software, sensitive
to any conditions outside of their maximum
operation parameters. The incidence of natural
and manmade induced voltage surge is increasing
- in one month alone, up to 72,000 lightning
strikes have been recorded in the UK - causing
an estimated cost of £50 million to
UK industry. |
|
|
|
The need for overvoltage Protection
to provide a reliable and secure environment, for the
lift blood of any business operations, has never been
greater The consequences of unprotected systems include:
danger to staff from from electrostatic discharge / side
flashing; unexplained operational problems loss of data
or corruption; physical damage to equipment (high repair/replacement
costs); complete loss of operations and systems downtime;
premature equipment ageing due to component stressing:
and increased maintenance costs. These problems are increasing
as electronic equipment becomes smaller yet more powerful.
An estimated 70 per cent of all faults are caused by surge
and transients induced onto data communication and power
lines.
The problem
Lightning can contain up to 200,000 amps with an average
value of about 35,000 amps In excess of 75 per cent of
all ligh- tning strikes can contain up to success- ive
strikes which are discharged over a period of 30-200 milliseconds.
Most important and the most damaging effect of transients
is the rate at which these current and voltage rise which
can be excess of 10,000 amps every microsecond ( millionth
of a second ), and 12,000 volts every microsecond. these
impulses enter electronic systems, the most odvious via
a direct strike. However, most subtle mechanisms can induce
these dangerous influences to be conveyed on power, communication
and data lines, many kilometres from the strike point.
the cost of damage to computing, communications and information
capital equipment can be very substantial. To get a full
picture of the cost, it is necessary to add the cost of
replacing equipment to the cost of operational downtime
and the loss of commercial opportunities.
The Solution
In order to provide ad effective solution from the effects
of transient overvoltage and surge damage to communications
and IT systems, the problem needs to be quantified. This
can be done by carrying out a risk assessment to the requirements
of BS 6651 [1992] protection of structures and Electronic
Equipment against lightning. BS 6651 [1992] assesses the
risk of an installation to transient overvoltage in terms
of the collection (attractiveness) to induced voltages,
calculates the number of transient incident on the on
the system pre year, the effect of damage, its impact
on the operation and the location and category of protection
method needs to be implemented to provide full protection.
This is carried out by a site installation survey.
Six Point Protection Plan
over 20 years of experience and analysis has led to a
systematic integrated approach to transient overvoltage
and surge protection, using the six point protection plan,
which is based on national and international standards
- including BS 6651 [ 1992 ], BABT, IEC 1024 and IEEE
C62.41 - to ensure the highest levels of security.
<
Back to news list |
|
About
the author:
Alistair Hunt is the Technical Director for Telecom
protection Technologies. A physics graduate, he
has been involved in the design and development
of transient overvoltage protection components and
protection system for mains, power data, signalling
and telecom equipment for over 16 years. He is also
an active member of the BSI and ICE working group
committees for the setting of specifications and
standards in the protection of electrical and electronic
systems against lightning and transient over voltages.
|
|
