In Australia, bushfires have directly resulted in millions of dollars in financial damage, the destruction of sensitive natural areas and wildlife habitats, and tragically, the loss of human life. Outside Australia, bushfires have been linked to liabilities in the hundreds of millions of dollars for power utilities, and some have even faced bankruptcy as a result.

Distribution network providers are actively exploring options to reduce the risk of their equipment starting bushfires. One area of potential risk that utilities have identified, in cooperation with suppliers like Hitachi ABB Power Grids, is surge arresters installed on distribution overhead lines traversing bushfire prone areas – particularly those located above forest grass and leaf litter.

Bushfire risks posed by surge arresters

Surge arresters provide an important function on the electrical grid by protecting critical and expensive equipment from damaging over voltages. Where the consequential absorbed surge energy is beyond the arrester’s thermal recovery/runaway threshold, the surge arrester is designed to sacrifice itself to protect the downstream electrical equipment. 

This self-sacrifice event can be quite dramatic, with the violent expulsion of hot gasses and incandescent particles which can ignite fires, damaging property and injuring people nearby. 

These events are rare, but their risk profile fits the definition of what is known as a ‘black swan’ event – one that has a low probability of occurring but has potentially serious or catastrophic consequences.

Therefore, Hitachi ABB Power Grids invented an innovative Spark Prevention Unit (SPU) surge arrester to monitor surge arrester overloads and safety disconnect from the network to prevent the sparks that can cause bushfires. Over the past four years, tens of thousands of SPUs have been deployed globally in locations where the risk of wildfire is a particularly grave concern.

Australian distribution utilities embracing the Spark Prevention Unit 

United Energy in Victoria is leading the way by installing SPUs to reduce the risk of bushfires due to surge arrester overloads. Horizon Power in Western Australia is utilising SPUs to improve reliability in areas of extreme lightning intensity which increases risks of overloading arresters installed on unshielded overhead distribution lines.

Currently there are around 2,000 SPUs installed in Australia. While alone the SPU can’t eliminate all bushfire risks, United Energy is looking to the SPU as a key element of their overall bushfire mitigation program.

How the Spark Prevention Unit works

The SPU effectively models the current, transient thermal loading status of surge arresters and safely disconnects overloaded surge arresters from the network prior to them being driven to short circuit failure by network power frequency voltage. 

If a thermal overload is detected, the SPU interrupts the current flow and disconnects the surge arrester, which eliminates the risk of arcing, sparking or ejection of hot particles that have the potential to start a bushfire. 

A visual indicator lets the operator know the surge arrestor has been safety disconnected and flags a requirement to replace the equipment. The SPU can be deployed on distribution systems in every kind of terrain in any location.

This includes remote, fire-prone areas where it offers out-of-sight, round-the-clock protection, as well as in more populated urban areas where catastrophic failures pose a risk to public safety.

This sponsored editorial was brought to you by Hitachi ABB Power Grids. For more information, visit

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