How Does ELASTOSIL® RT 628 Protect Transformer Windings?

How to Effectively Protect Transformer Windings? The Role of ELASTOSIL® RT 628 A/B Silicone in Modern Electrical Engineering

Transformer windings are among the most critical components of any power system. They operate continuously under the influence of heat, vibration, moisture, and fluctuating electrical loads. In such environments, it is not only the construction of the winding itself that is crucial, but also the method of its protection. Increasingly, ELASTOSIL® RT 628 A/B RTV-2 silicone is being utilized in this field, combining durable electrical insulation with flexibility and resistance to extreme operating conditions.

Why Do Windings Require Flexible Protection? Unlike rigid epoxy resins, transformer windings need a material that "works" with them. During heating and cooling cycles, thermal expansion occurs in both the conductors and the core. A potting compound that is too rigid can lead to micro-cracks and mechanical stress, ultimately resulting in insulation failure. Once cured, ELASTOSIL® RT 628 A/B forms a permanently flexible silicone elastomer that effectively compensates for mechanical stress, protecting the windings from degradation over a long service life.

Excellent Electrical Insulation and Temperature Resistance One of the key features of RT 628 is its high electrical insulation capacity, making it an ideal material for protecting live components. The silicone maintains stable dielectric properties even during long-term operation at elevated temperatures. The material can operate within a range of –50°C to +180°C, allowing it to be used in low-voltage transformers as well as more demanding industrial and power applications, including varying climatic conditions.

Flowability and Precision Filling of Winding Gaps ELASTOSIL® RT 628 A/B is a low-viscosity, self-leveling silicone, which allows it to penetrate deep into the spaces between the winding coils. This effectively eliminates air bubbles and localized moisture concentration points that could otherwise lead to partial discharges or wire corrosion. For applications requiring the highest potting quality, vacuum potting can be employed, making RT 628 fully compatible with advanced industrial processes.

Environmental Resistance and Longevity After curing, RT 628 silicone exhibits very high resistance to moisture, UV radiation, and weathering. Consequently, it excels not only in indoor transformers but also in outdoor installations and high-humidity environments. This long-term stability is why ELASTOSIL® RT 628 A/B is also widely used in generators and other power equipment where reliability is of paramount importance.

Flexible Integration into Production Processes With its addition-curing system and a 9:1 mixing ratio, RT 628 offers a stable and repeatable process. Furthermore, its reactivity can be adjusted using dedicated WACKER catalysts or inhibitors, allowing for precise control over pot life and curing time to match specific transformer manufacturing technologies.

Where Does RT 628 Excel Most? ELASTOSIL® RT 628 A/B is primarily used for:

• Protecting windings in low and medium-voltage transformers.

• Flexible mounting of generator windings.

• Potting electrical components requiring insulation and heat resistance.

• Power industry applications, including hydropower installations.

In modern electrical engineering, there is a clear shift away from rigid potting systems toward flexible RTV-2 silicones. ELASTOSIL® RT 628 A/B perfectly meets these needs, offering a combination of electrical insulation, thermal resistance, flexibility, and longevity. It is a solution that significantly increases the reliability of transformer windings and allows for the design of equipment ready for years of trouble-free operation.