Page 7 - Surge-Protection-E_0.pdf

Planned Safety

Failure of technical installations and systems in residential and functional
buildings is very unpleasant and expensive. Therefore, faultless operation 3 million
of devices must be ensured both during normal operation and thunder- 2.5 million
storms. The number of annually registered lightning activities in Germany 2 million
has remained at a constantly high level over many years. The damage 1.5 million
statistics of insurance companies clearly show that there are deficits in Registered lightning strikes 1 million
terms of lightning and surge protection measures both in the private and
commercial sector (Figure 1). 0.5 million
With a professional approach, suitable protective measures can be im- 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
plemented. The lightning protection zone concept, for example, enables
planners, installers and operators of buildings and installations to consid- Ref.: Gesamtverband der Deutschen Versicherungsgesellschaft e.V. + BLIDS Year

er, implement and monitor various protective measures. In this way, all
relevant devices, equipment and systems can be reliably protected at an Figure 1: Lightning activity registered in Germany from 2000 to 2015.
economically justifiable cost.

Sources of interference
Surges occurring during a thunderstorm are caused by direct / nearby
light ning strikes or remote lightning strikes (Figure 2 and Figure 3).
Direct or nearby lightning strikes are lightning strikes to a building, its
surroundings or electrically conductive systems entering the building (e.g.
low-voltage supply, telecommunication and data lines). The resulting im-
pulse currents and impulse voltages as well as the associated electromag-
netic field are particularly dangerous for the devices and installations to
be protected with regard to the amplitude and energy content involved. 2 km
In case of a direct or nearby lightning strike, surges are caused by the
voltage drop at the conventional earthing impedance Rst and the resulting
potential rise of the building in relation to the remote earth (Figure 3,
case 2). This represents the highest load for electrical installations in
buildings.
The characteristic parameters of the impulse current that flows (peak val- electrically conductive systems
ue, rate of current rise, charge, specific energy) can be described by the
10/350 μs impulse current wave form and are defined in international,
European and national standards as the test current for components and Figure 2: General risks for buildings and installations resulting from lightning
devices for protection against direct lightning strikes (Figure 4). strikes.

Direct / nearby lightning strike: Remote lightning strike:
Lightning strike to the external lightning protection system, 4 Lightning strike to medium-voltage overhead line
1
process frame (in industrial plants), cables etc.
Travelling surge waves in overhead line due
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2 Voltage drop at the conventional earthing to cloud-to-cloud flashes
impedance Rst
6 Fields of the lightning channel
3 Induced voltage in loop

20 kV
IT
L1
L2
L3
PEN

R st

Lightning equipotential bonding Low-voltage supply system External lightning protection system
Lightning current arrester / Information technology system IT Information technology
Combined arrester

Figure 3: Causes of surges during lightning discharges.

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