Learnings

Outcomes

Circuits that have had lightning surge arresters installed on them have experienced a 42% improvement in IIS costs due to lightning vs the previous three years where no lightning protection has been installed and a 76% improvement when comparing against the previous 10 years. This has been calculated by measuring lightning related IIS costs for the years before and after lightning protection devices were installed. However, even with a 42% improvement in IIS costs, the payback period is 19 years, which is longer than the expected lifespan of the surge arresters. It is probably unfair to compare IIS costs to the previous 10 years as many circuits have been changed over the time e.g. back-fed to reduce IIS impact. It is clear that lightning protection can play a role for reducing IIS costs, but it needs to be cheaper or longer lasting to have a cost benefit. This is one of the key reasons for trialling the streamer devices as part of this project.

Lessons Learnt

An interesting early finding was that the circuits deemed highest risk of experiencing lightning faults by the data analytics phase were significantly different from those circuits that historically have been recorded as experiencing lightning faults in our fault database. This could possibly mean:

1) Labelling of faults as being caused by lightning may be incorrect. It may be that extreme weather and water ingress is the problem rather than lightning, therefore it may be more prudent to alter maintenance/replacement cycles associated with overhead circuit assets rather than protect circuits against lightning.

2) The analytics algorithm could be incorrect and therefore not be correctly identifying the highest risk circuits.

With the course of the project entering monitoring phase, more certainty will be gained as to whether point 1 or 2 is correct, as we will be able to track whether lighting caused a fault with a greater level of certainty through additional monitoring.