Anhydride-Free Epoxy Material for HV Insulation

High voltage (HV) equipment, such as HV transformer bushings, spacers for GIS (gas insulated substation) and GIS/cable termination classically use epoxy composites as structural and insulating parts. These materials now face different challenges, regarding both safety and performances. First, anhydride pre-polymers are commonly used in the preparation of the final epoxy material network. These chemicals are to be restricted in the future by REACh regulation due to their respiratory sensitizer label. Recent formulations, not involving anhydride, have been developed by epoxy suppliers [1] . In addition, there is a general trend to increase the operating temperature of the HV equipment. For high voltage switchgear, the IEC 62271-1-2017 standard has increased the upper limit of temperature from 105 to 115 °C for contacts and connections. This new limit is above the glass transition temperature (Tg) value of commonly used epoxy resins.