Electrical power systems are responsible for delivering electricity from generators to the end-consumer. Protection of these systems is necessary to ensure safety of personnel, to protect expensive assets and to ensure continuity of supply.
Within electrical substations, a distance should be maintained between any energised conductor and any other part of the substation, including the earth.
Numerous standards and regulations have been proposed in order to guarantee the safety of people and the installation of electrical appliances. In fact, electrical shock, known as electrocution, is at the top of the list of domestic accidents.
Under fault events, current flows through the earthing system causing an earth potential rise (EPR), also known as ground potential rise (GPR), and results in a non-uniform distribution of the potential on the earth surface.
Energy consumption needs are expanding rapidly around the globe in the recent decades. Indeed, there are many reasons behind this enthusiasm such as the increase in population as well as the rise in commercial and industrial activities.
Lightning consists of an electric discharge in a long air-gap involving an electrostatic phenomenon of breakdown of the air between cloud and earth. In this case, it is clear that an enormous voltage is involved, which means a huge amount of energy.
Human-beings, animals and structures are potentially exposed to several types of electric threat of different characteristics. The main are direct lightning strikes and the consequences resulting from the discharges.
An effective lightning protection system is mainly composed of two forms (i.e., internal and external) of protection systems, depending on their functionality. External lightning protection systems include different design methodologies to protect structures or buildings, as well as open areas and people from direct lightning strikes.
For safety reasons, lightning protection systems must also react to any induced electrical potential such as that developed on the ground surface around the point of current injection. Therefore, the protection system may differ from one system to another according to multiple factors such as the system to be protected and transient source.
Lightning is mostly a consequence of the development of a convective weather system to a certain magnitude, with strong links to the development of discharge processes within the system. An air volume can be uplifted in an unstable convective condition, taking part in the development of cumulonimbus.
Every day, an average of around 8 million lightning strikes discharges over the earth, which is the equivalent of about 100 lightning bolts that strike the Earth’s surface every second. Lightning detection and monitoring are very important to improve public safety, warn of potential wildfires, and protect electrical systems.
A requirement is to ensure that buildings are provided with lightning and surge protection systems in accordance with national and international standards. There are a large number of ways in which lightning and surges can interact with electronic equipment
Effective earthing system is essential to ensure the safety of people and reliable operation of the whole group of electrical installation.
Soil electrical resistivity represents a key factor in the design of appropriate earthing systems because of its direct proportionality with the earthing resistance.
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