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Siemens selects natural ester fluid on 420 kV transformer

Siemens selects rapeseed over soya-based ester fluid on a power transformer for German transmission system operator TransnetBW.

Besides having to be filled with natural ester fluid rather than mineral oil, the transformer had to demonstrate robust cold start capability. A supplemental requirement was for the natural ester fluid to be made from European-grown crops.

Siemens was already familiar with the characteristics of natural ester transformer fluids, specifically those made from soya and rapeseed crops, having used soya-based ester fluid in a power transformer unit in 2014. However, the manufacturer independently acknowledged the superior cold weather performance of rapeseed ester fluid with its pour point of -31°C. This critical performance factor made it necessary to upgrade to a rapeseed based ester.

“The innovative cold start technology in this transformer demonstrates Siemens’ expertise in combining industry leading innovations with eco-friendly solutions for the benefits of our customers and society”, said Dr. Beatrix Natter, CEO, Siemens Energy Transmission.

In addition to this performance advantage, the use of rapeseed ester MIDEL eN 1204 satisfied the local authority’s mandate for the transformer materials to be locally sourced – MIDEL’s aggregated source for the rapeseed being central Europe. The transformer for TransnetBW used over 100 t of fluid.

Leading utilities such as Con Ed and National Grid are also producing greener transformers by using ester transformer fluids.

MIDEL eN 1204 delivered clear benefits in this project; the fluid has a high fire point (K class fluid > 300 °C) and is readily / fully biodegradable. Its superior performance over soya natural ester fluid at lower temperatures was a critical factor for the customer, enabling the transformer to withstand a cold start after any period of outage.

Source: MIDEL