Green Transformers: Advancing Sustainable Power Distribution
The electrical industry is one of the many industries playing its part in developing sustainable energy practices. When it comes to the transmission and distribution of electricity and the modernisation of the power grid, green transformers are effective modern-day solutions. In addition to improving energy efficiency and lowering CO2 emissions, green transformers have improved fire safety, enhanced life cycle, and require less maintenance.
It should come as no surprise that the demand for green power transformers is growing. The market size is projected to increase by over 6.5% from 2023–2032. The expansion of renewable energy projects and the increasing need to reduce energy losses during power transmission and distribution support this growth.
To ensure both the longevity and performance of these green transformers, design engineers need to select materials that can withstand the most challenging applications, have high thermal and mechanical resistance, as well as high chemical compatibility.
Safer Energy Distribution and Environmental Excellence
The base materials within green transformers are derived from bio-based ester oils, which have significantly better fire retardance. Unlike mineral oil alternatives, ester oils have a higher fire point (over 300° Celsius compared to 170° Celsius for mineral oil). These fire safety advantages enable green transformers to operate at higher temperatures, which also facilitates increased power distribution. Green transformers are specifically designed for more energy-efficient operations, resulting in reduced power loss. Furthermore, there is no need to increase the weight and size of the transformer unit. Ester oil transformers can be more compact while delivering the same power output as mineral oil transformers, thereby saving space.
Research indicates that ester fluids are superior in performance and are more environmentally friendly alternatives to mineral oils. Ester fluids are non-toxic and biodegradable. In the event of an oil spill, these oils decompose quickly and do not pose an environmental hazard. This makes spill mitigation, clean-up, and recycling processes simpler and more cost-effective.
Utilising bio-based materials also contributes to a longer equipment lifecycle. Compared to mineral oils, ester oil is more resistant to oxidation and oxidative degradation. Ester oils also have a high water saturation limit, enabling them to absorb moisture from cellulose paper up to 10 times faster than mineral oils. This helps prevent transformer failure by protecting the cellulose insulation. Esters can tolerate higher moisture levels without compromising their dielectric properties.
With reduced pollution risks, smaller size, improved efficiency, lower maintenance costs, optimised lifecycle, and enhanced safety due to reduced flammability, green transformers represent a robust and more sustainable alternative to traditional transformers.
Common challenges and how to mitigate them to optimise performance
Saint-Gobain® Tape Solutions offers a wide range of adhesive tapes that provide proven chemical stability, long-term thermal capability, and superior adhesion. Acrylic adhesives have variations within their formulations, which assist design engineers in achieving better chemical compatibility with transformer oils.
One important consideration when selecting products for green transformers, in particular, is that ester oils are more aggressive towards plastic materials exposed to them, increasing the likelihood of plastic degradation. When plastic materials degrade, they can contaminate the oil and reduce its electrical insulation capability. If the electrical insulation capability is significantly compromised, the transformer may fail.
Have you ever heard a transformer on a telephone pole blow? It sounds like a loud gunshot or firecracker explosion, and this is the sound of a transformer reaching its failure point.
Filament reinforced tapes with paper backing vs. polyester
Because ester oils and synthetic oils are more aggressive towards plastics than traditional mineral oils, products made with filament-reinforced paper perform better compared to those made with filament-reinforced polyester. Filament-reinforced tapes with paper backings, including products such as PG.70, 6601, and our newly formulated in-development product, are the preferred choice when avoiding the possibility of air bubbles in insulation oils is critical.
Generally, if there is an air bubble in a transformer, it creates corona discharge, which can lead to premature failure. Tapes with paper backing allow the oil to fully penetrate, eliminating the chances of air bubbles forming. While products such as PS.25 and PS.249, which have plastic film (polyester), generally perform well, they also have a higher likelihood of trapping air bubbles between the tape and electrical wires in green transformer applications. These products are better suited for traditional mineral transformers rather than green transformers, where the oil's aggressiveness is higher.
Other considerations when selecting the best product for green transformer applications include oil compatibility and resistance. Customers seek products that will not dissolve in synthetic and natural ester oils, as this leads to contamination and premature failure of oil-filled transformers. Products with better oil compatibility with natural esters can extend the lifespan of transformers by years. However, the challenge lies in the fact that polyester filament tape products often exhibit superior oil resistance, while paper filament tape products are more conformable and better at preventing issues such as corona discharge. As a result, our teams have developed a new product, which will soon be available to address these challenges.
Product spotlight: new in-development product variation of CHR® 6601
Our new in-development product is specifically designed for heavy-duty air and oil-filled transformer applications, reinforcements, and insulation. This product consists of a glass fibre-reinforced paper backing with acrylic pressure-sensitive adhesive. Its superior tensile strength, adhesion, and dielectric properties make it the premier product for heavy banding and holding applications in large-scale coil winding processes, such as those used in transformers, generators, and motors.
Acrylic adhesive tape compatibility in ester fluids: a clear winner
There are various tests that can be conducted to determine the compatibility of adhesive tapes in oil. At Saint-Gobain Tape Solutions, our teams have studied the behaviour and compatibility of various acrylic adhesive tapes after immersion in ester oils such as Cargill FR3, Natural Ester A, Synthetic Ester A, and Natural Ester B.
Two common tests include the swelling test and the peel adhesion test. Below is a summary of each test and the results:
- Swelling Test: The purpose of this test is to analyse the adhesive's behaviour after being soaked in the aforementioned ester oils. In this test, tapes are cut into strips of 25mm or 10mm in width and immersed in jars filled with oil, ensuring that each adhesive tape is completely saturated with each oil type. The jars are sealed to prevent the entry of new oxygen. These tapes are then placed in an oven for 24 hours at 100°C to undergo ageing. Afterwards, the specimens are extracted for visual inspection and consistency testing.
The results of this test showed that Cargill FR3 and other natural ester oils were significantly less aggressive towards the various adhesives compared to synthetic oils. However, this newest in-development product demonstrated excellent resistance in all fluids without showing visible damage or swelling.
- Peel Adhesion: This is a quantitative 180° peel adhesion test of the tape from an aluminium substrate before and after oil exposure. The preparation and ageing of the samples are the same as in the swelling test; however, the adhesive tape strips are applied to a metallic surface before being immersed in the oils. The tapes are then peeled at a constant speed, and the resulting force is measured using a dynamometer.
In this test, the performance of CHR 6602 demonstrated superiority. It showed improved performance, likely due to the efficient heat transmission of the fluids not affecting the adhesive chemistry.
Understanding interaction of tapes drives to enhance longevity
Understanding the interaction of adhesive tapes with oil is crucial when designing and manufacturing green transformers. Adhesive tapes must exhibit strong adhesive interactions with bio-based ester oils, as well as high tensile strength and absorption capabilities, to ensure optimal electrical performance, conserve energy, and minimise the risk of transformer failure. With advancements in technology and increasing efforts to develop safer and more sustainable solutions, bio-based transformers may play a key role in reducing pollution, minimising fire risks, and creating safer options that meet future needs. Enhanced performance, reduced maintenance, and increased longevity of green transformers make them a financially viable and environmentally responsible solution for electricity transmission and distribution.
