One of the biggest and busiest airports in Africa, OR Tambo International in Johannesburg, was plunged into temporary darkness on Sunday 12 December last year after a transformer at a substation in Kempton Park caught fire. While this highlights the vulnerability of such critical electrical infrastructure, CEO of ASP Fire, Michael van Niekerk, points out various measures that local authorities can implement to manage such fire risks.

The fact that substations are not manned means there is no-one on site to raise an alert in the event of any incident. In addition, a lack of maintenance means an increased likelihood of such incidents. The situation is exacerbated by load shedding, which results in current inrushes when the power is restored – and these can damage components such as ageing electrical insulation, increasing the risk of transformer fires.

Managing the risk of fire at substations

A lack of maintenance on municipal substations and ongoing load shedding from national grid, raise the risk of damaging ageing electrical infrastructure – and the risk of substation fires.

Some substations are in remote areas, or in locations that are difficult to access after normal business hours. At these substations the installation of a standalone fire-detection system is recommended to protect high-risk items such as the transformers. In addition, a fire-suppression system using foam mist can be highly effective.

However, Van Niekerk notes that the dangerous combination of load shedding and a lack of preventive maintenance can result in arc flashes, which he describes as, basically, mini lightning bolts that can cause the insulation in substations to start burning. A lack of adequate maintenance of the cooling oil in a transformer can cause hot-spot temperatures that result in bubbles in the oil which, combined with high temperatures, increase internal tank pressure and may result in overflow or tank rupture.

It is exactly this kind of combination of factors that gives rise to so many reports of substations catching fire – and the resultant power outages as well as the destruction of infrastructure.

ASP Fire can supply and install standalone fire-suppression systems which are not reliant on pumps and water-storage tanks in the event of a fire. Water is, instead, stored in nearby pressure vessels. This system has the added benefit of minimising the quantity of water needed to suppress a fire.

The major problem, however, remains the lack of adequate maintenance. “We are all aware of the challenges faced by local government in maintaining essential infrastructure. Ageing substations that are not well-maintained to begin with are increasingly vulnerable to load shedding – and what can then be disastrous consequences,” van Niekerk warns.

The installation of adequate fire detection and suppression systems offers a simple solution, but this is constrained by a lack of necessary funding. Consistent preventive maintenance is therefore essential to ensure that substations are robust enough to cope with load shedding, and it will enable local authorities to save on capex costs.

While local authorities have to adhere to strict regulations in terms of electrical safety, the installation of fire detection and suppression systems is not mandatory. An exception is in the mining industry, which operates its own substations. Here electricity is essential to ensure life-critical equipment such as ventilation shafts and personnel lifts are operational at all times.

Van Niekerk emphasises that the knock-on effect of fires at substations is huge for the whole South African economy. “The cost in replacing a single transformer is prohibitive, and this behoves local authorities to ensure they have a maintenance schedule in place, and/or have conducted a fire-risk assessment, even if they are not in a position, financially, to install proper fire detection and suppression systems immediately.”

For more information contact ASP Fire. Tel: +27 (0) 11 452 2169, email: michael@aspfire.co.za

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