Transmission & distribution |
Ester oil transformers: a CHINT perspective
Traditionally, transformers have relied on mineral oil for both electrical insulation and cooling. However, mineral oil poses significant drawbacks: it is derived from non-renewable sources, presents environmental risks if spilled, and has a relatively low flashpoint, making it a potential fire hazard.
As an alternative, ester oils, derived from renewable sources like soybeans and other vegetable oils, offer excellent insulating properties, coupled with a higher flashpoint, which significantly reduces fire risk. They are also biodegradable and non-toxic, greatly minimising environmental impacts in the event of a leak or spill. This enhances the safety of transformers, particularly in urban or environmentally sensitive locations.
Ester oils are not just safer and more environmentally friendly, they also enhance transformer performance. Their ability to absorb more moisture than mineral oil results in dryer dielectric paper within the transformer, which in turn extends the life of the insulation. Additionally, ester oil transformers can operate at higher temperatures, further contributing to extended operational life and reduced maintenance requirements.
Experimental studies have shown that ester- filled transformers exhibit favourable electrical properties, including a more homogeneous electric field around the transformer’s winding wedges. Recent research indicates that ester oil transformers can extend insulation life by up to 5-8 times compared to mineral oil transformers under similar operating conditions. Despite the numerous advantages, there are some drawbacks to using ester oil transformers, including larger equipment size and higher manufacturing costs. These factors could potentially hinder their widespread adoption. Ongoing research and development efforts are aimed at mitigating these disadvantages, optimising performance, and improving cost- effectiveness. As a result, specifically designed transformers have been developed to overcome these challenges.
For example, a high-voltage variant of the ester oil transformer has been developed by CHINT to address the needs of large-scale power transmission networks. This represents a significant step forward in the deployment of ester oil technology in critical, large-scale applications, bringing the benefits of ester oil to a broader range of applications. Importantly, CHINT has already successfully tested a prototype single-phase transformer filled with natural ester FR3 at this ultra-high voltage level, demonstrating the viability of the technology for large-scale power transmission.
CHINT’s range of ester oil transformers also includes medium=n voltage options, suitable
for distribution networks and renewable energy integration. Their 110 kV and 220 kV ester oil transformers have shown a 20% reduction in total ownership costs over a 30-year lifespan compared to traditional mineral oil transformers, factoring in reduced maintenance and longer service life.
Meeting market trends Several market trends within the global power transformer market drive not only demand, but also the type of solution required. A growing need for electrical energy, to meet rising population levels and increased industrialisation, particularly in developing regions of the world, is foremost among these pressures.
Many developed areas, such as North America and Europe, also require more modern transformers to upgrade or replace ageing power infrastructure.
Countries are also considering smart power grids, which allow better energy management and distribution. This will require advanced transformers with improved monitoring and automation capabilities.
The global power transformer market has also seen a gradual shift towards renewable energy sources and eco-friendly solutions, driven by regulatory pressure, consumer demand for sustainable products, and the economic benefits of green technologies.
Transformers will be needed that can handle variable loads while integrating with traditional power grids.
With their environmental and operational advantages, ester oil transformers are well- positioned to capitalise on these trends. The longevity and low maintenance requirements of ester oil transformers make them an attractive option for upgrading aging infrastructure, and for new build projects.
A recent case study by CHINT in collaboration with a major European utility showed that implementing ester oil transformers in a smart grid project resulted in a 15% improvement in overall grid efficiency and a 30% reduction in maintenance-related downtime. As the power sector evolves, ester oil transformers are poised to become even more efficient, reliable, and environmentally friendly. Ongoing research and development are focused on enhancing the properties of ester oils and optimising transformer designs.
Future formulations of ester oils are expected to improve biodegradability characteristics
34 | October 2024|
www.modernpowersystems.com
and thermal stability, allowing transformers to operate at higher temperatures with reduced degradation. Enhanced cooling systems, including hybrid solutions that combine ester oil with air or water cooling, are being explored to boost overall efficiency.
Innovations in insulating materials will complement ester oils, offering better dielectric strength and moisture resistance. The integration of smart technologies such as IoT devices and sensors will enable the real-time monitoring of key parameters like temperature and moisture levels, facilitating
CHINT 750 kV ester oil
transformer
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