Datacentres are a crucial part of the modern digital age. In almost every aspect of our everyday life, a datacentre is part of the flow of information. Whether it is social media, entertainment, public health, energy, telecommunications, traffic control systems or government agencies; all these aspects of our lives rely on the reliability and security of information flowing from datacentres.
A datacentre is not just a large structure but also filled with critical infrastructure that can be highly sensitive and very expensive. The dangers posed by lightning and surges represent a significant risk to the smooth and reliable flow of information. A lack of precautions to mitigate these risks can lead to fires, downtime of important systems, and potential loss of data.
Lightning and surge protection measures are an essential component in the overall safety concept, because a datacentre is so much more than just a building. The essential elements of the protection concept include:
- External lightning protection to prevent random strikes
- Equipotential bonding of the building to provide shielding
- Earthing system to ensure dissipation of lightning energy
- Surge protection for electrical infrastructure
The first step in the protection measures is always to undertake a risk assessment according to AS 1768 and/or IEC 62305. The risk assessment will confirm the need for a Lightning Protection System (LPS) and provide the Lightning Protection Level (LPL) required for the design. A Rolling Sphere Method is used to design the height and layout of air terminals to provide protection against direct strikes. An appropriate down conductor design according to the standards will channel the lightning energy safely to earth.
Often a mesh system is incorporated in the datacentre building design to enhance the LPS. The mesh provides an equipotential bonding network and a Faraday Cage effect for the building to guard against the electromagnetic field effect of lightning (LEMP).
The standards refer to Lightning Protection Zones LPZ) in a building, so the datacentre is divided into internal protection zones, as we do for most buildings. The zones are designated as LPZ 0 for the external part of the building, with LPZ 1 just inside and progressing to LPZ1, LPZ 2 etc as we get deeper into the building. In essence, the standard recommends a level of surge protection at each boundary of a zone. The service entrance of the building or main switchboard is the transition from LPZ 0 to LPZ 1, a sub-distribution board would be the transition from LPZ 1 to LPZ 2 etc. Each zone junction should have a level of surge protection.
Using a simple three stage protection principle, an effective surge protection concept can be visualised.
Stage 1 represents Type 1 lightning current arresters or Type 1+2 combined arresters at the entrance of the services to the building.
Stage 2 is usually Type 2 arresters installed on sub-switchboards and distribution boards
Stage 3 can be Type 2 or Type 3 surge arresters installed at the final distribution equipment
System availability is crucial in datacentres and this can only be achieved if suitable measures are taken to ensure internal lightning protection as well as external lightning protection. A well-designed lightning and surge protection solution will consider the effects of direct and indirect lightning strikes, grid and load switching and electromagnetic interference across power, data and signal cabling.
IPD can provide advice and solutions for lightning and surge protection for all applications.