Written by Ian Richardson, National Sales Development - Surge and Lightning Protection
Global warming has a significant impact on lightning strikes, as acknowledged by the international scientific community. For every 1°C increase in global warming, there is an approximate 12% rise in lightning strikes. A recent study by the University of California, Berkeley found that the ongoing warming conditions would lead to a staggering 50% increase in lightning strikes by the year 2100. Australia has been identified as one of the countries most affected by this phenomenon. The core reasoning behind this escalation is the heightened moisture stored in clouds, facilitated by global warming, which is at the heart of lightning formation.
The CSIRO and Bureau of Meteorology (BoM) published the 2022 State of the Climate Report, which provided data on the average annual temperature of Australia since 1910. The report indicated a slow increase in average temperature up to 1960, with the growth rate becoming more severe since 1960. The Australian average temperature had increased by approximately 1o C over 90 years from 1910 to 2000 but has risen a further 0.5o C degrees from 2000 to 2022. This acceleration of the change is of concern.
The Australian Lightning Protection Standard, AS 1768:2021, includes a map of the average annual lightning ground flash density (lightning strikes) across Australia. This map provides essential input into the lightning risk assessment process of the standard. However, the map has a shortcoming. The lightning ground flash density data is averaged from 1995 to 2012. Since then, the State of the Climate Report has observed more rapid increases in the average annual temperature.
Solving the global warming issue and the resultant increase in lightning activity will take significant time. Fortunately, we have innovative solutions to protect our assets.
The AS 1768:2021 risk assessment process is based on the IEC 62305-2 standard and is the first step in the protection measures for a site. Air terminals, down conductors, earth termination systems and equipotential bonding are all elements of a lightning protection system designed to intercept a lightning strike and protect the structure. Lightning impulse currents are significantly more destructive than typical surge or transient currents thus, special attention must be applied to implementing lightning protection measures for the electrical infrastructure. AS 1768:2021 states that surge protection shall be installed where the facility is to be protected against direct lightning strikes.
To mitigate the impact of these powerful lightning-related events on electrical equipment, we use Type 1 or Type 1+2 surge arresters for primary protection. These devices are tested to a 10/350μs waveform according to IEC standards, designed to characterise a lightning-related impulse. Type 2 surge arresters are used for secondary protection and tested with a lower energy 8/20μs waveform, replicating surge currents from distant lightning strikes, network switching and local load switching.
The solutions are readily available, easily installed and relatively inexpensive compared to the assets being protected. IPD has a full range of solutions from world-leading suppliers Dehn and Novaris and application assistance to ensure the right choice of protection for a site.