Uretrane encapsulants for switchgear transformers

Abstract

Epoxy resin systems are being used to encapsulate various switchgear transformers for indoor and outdoor applications. However, some manufacturers are experiencing stress cracking problems associated with this resin chemistry. For this reason, urethane electrical resin systems have been developed and marketed as an alternative because of their excellent thermal shock, flexibility, and stress relief properties over a wide temperature range. Further advantages of urethanes are: • Lower processing and cure temperature • Faster demold time/higher productivity • Stable electricals and good property retention up to 125°C • Fungus resistance • Will meet the requirements of UL 94V-0.