Electricity and Control September 2023

TRANSFORMERS, SUBSTATIONS + CABLES : PRODUCTS + SERVICES

Protecting substation transformers from fire

Continuing loadshedding has brought into focus the vul nerability of critical electrical infrastructure such as trans formers at substations. Michael van Niekerk, CEO at ASP Fire says this means local authorities need to implement specific measures to manage the fire risk. Substations, by their nature, do not have personnel on site, which means there is no one to raise an immediate alert in the event of any incident. In addition, where there is a lack of maintenance, this leads to an increased like lihood of such incidents. “The situation is exacerbated by loadshedding, which results in current inrushes when the power is restored. This can damage components such as ageing electrical insulation, and increases the risk of transformer fires,” says van Niekerk. In national and local supply networks, substation transformers are used to step down the electricity from 33 000 V to 11 000 V or 6 000 V. Some substations are in remote areas or in locations difficult to access outside of normal business hours. ASP Fire recommends the installation of a standalone fire-detection system to protect high-risk items like transformers. In addition, a fire-suppression system using foam mist can be highly effective. “The dangerous combination of loadshedding and a lack of preventive maintenance can result in arc flash es,” van Niekerk notes. These are like mini lightning bolts and can cause the insulation in substation transformers and other equipment to start burning. If the cooling oil in a transformer is not adequately maintained, hot-spot temperatures can result in bubbles in the oil which, com bined with high temperatures, increase internal tank pressure and may cause an overflow or tank rupture. ASP Fire can supply and install standalone fire suppression systems. These are systems that do not have to rely on pumps and water-storage tanks in the event of a fire. Water is, instead, stored in nearby pressure vessels. This has the added benefit of minimising the quantity of water needed to suppress a fire. Van Niekerk says the major problem 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 loadshedding,” he says. Although the installation of suitable fire detection and suppression systems offers a simple solution, the necessary funds are not always available. In such cases, consistent preventive maintenance should ensure that substations are robust enough to cope with loadshedding, and also allow local authorities to save on capex costs. According to van Niekerk, local authorities have to adhere to strict regulations in terms of electrical safety, but the installation of fire detection and suppression sys tems is not mandatory – as it is the mining industry, which operates its own substations and marks the exception. Here electricity is essential to ensure life-critical equip ment such as ventilation shafts and personnel lifts are operational at all times. “The impact of damaged transformers and substa tions is severe,” says van Niekerk. “And the cost of re placing a single transformer can be prohibitive. To es tablish a regular maintenance schedule, local authorities must conduct some kind of fire-risk assessment and take steps to safeguard electrical infrastructure from fire.” If aging substations are not well maintained, there is a higher risk of fire in transformers and other electrical equipment.

For more information visit: www.aspfire.co.za

SEPTEMBER 2023 Electricity + Control

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