Localised production facilities for natural ester dielectric fluid in South Africa

September 27th, 2018, Published in Articles: Energize

The use of natural ester dielectric fluid instead of mineral oil in power transformers offers many advantages and the announcement that a local factory is to be set up to produce this fluid is a very important development in South Africa’s energy sector.

Wilec, a division of Actom, currently imports natural ester dielectric fluid for use in power transformers. However, the company, in conjunction with its foreign supplier, has taken the initiative to set up a local factory on the East Rand to manufacture natural ester oil for this purpose.

Louis Blom

Speaking to Energize recently, Louis Blom, Wilec’s sales and marketing executive, said that Eskom specifies natural ester dielectric fluid for its transformers. Furthermore, it is Eskom’s intention to conclude studies into the feasibility of adopting natural ester dielectric fluids for small pole and ground-mounted transformers (termed Class 0), with a view to specifying them for standard use.

The deployment of this fluid in larger transformers is envisaged in the coming years. A memorandum of agreement was signed by Eskom and the IDC to establish a sustainable value chain which may involve farming of the seed crops, processing the oil and distributing it to transformer manufacturers.

Engineering research will also be conducted to answer all related technical questions. This has the potential of displacing 4-million litres of imported mineral oil at an annual cost of approximately R88-million while creating much-needed jobs.

According to Blom, it is anticipated that the demand for first natural ester-filled transformers will commence during the latter end of 2018 or early 2019. A 20 MVA 88/6,6 kV transformer has already been commissioned for Eskom at PPC Slurry in Mafikeng. The transformer was designed and manufactured by Powertech Power Transformers and filled with Envirotemp FR3.

Envirotemp FR3 is the brand-name used by Cargill, the foreign company which manufactures the fluid. Blom said that Wilec has been importing this fluid from Cargill for many years and is confident that a black-owned local manufacturing facility, which Cargill and Wilec are supporting jointly, will deliver real benefits to the local industry as well as meeting Eskom’s local content requirements.

Apparently, natural ester dielectric fluid can be made from soy beans. Soybean oil has long-chain fatty acids which makes it ideal for use as a coolant in power transformers. The oil is totally non-toxic and completely biodegradable meaning that in the case of a leak no environmental harm will follow. In fact, the oil dissipates into the soil within a short period of time. The fluid is known to extend insulation life due to its characteristic quality of continuously drying out the paper, keeping the transformer reliable for longer.

Another advantage is that, should the oil catch fire, it is self-extinguishing. This means that the transformer will suffer less damage and could be reenergised very quickly. This would, in turn, result in shorter power outages saving utilities thousands of rand and users a great deal of inconvenience.

Demand for the product is expected to grow exponentially as additional substations are built and existing ones upgraded to meet the demand of Eskom’s ongoing electrification programme and the rollout of more renewable energy based generating sites which will all require substation transformers.

Although natural ester dielectric fluid is more expensive than mineral oil, producing the fluid locally would offer significant savings. There would be no forex fees, no exchange rate fluctuations and no import duties to pay. It also meets local content requirements. Furthermore, a local factory would source the beans from local farmers which would good for agricultural sector and job creation.

The platinum mines in South Africa have converted most of their mineral oil filled transformers to Cargill’s dielectric fluid due to improved efficiency, transformer life extension and fire risk mitigation. The mines are also capitalising on the overload capability of the transformers which have been filled with this natural ester dielectric fluid.

According to Blom, natural ester dielectric fluid has a higher flash point than mineral oil (typically 300°C vs. 155°C), can handle long periods of higher temperatures resulting from overloads and could result in cost savings as the transformers could be physically smaller than a similarly rated one using mineral oil.

Power utilities are already calling for natural esters instead of mineral oil, he said, and a local manufacturing plant offers advantages way beyond the power sector.

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