Thermal Properties of Environmentally Friendly Dielectrics used in Medium Voltage Circuit Breakers

There is a need to replace an epoxy tie rod, which is used as the insulation and structural component within a vacuum circuit breaker, by an alternative environmentally friendly material. A selection process has demonstrated that glass filled thermoplastics are candidates. This paper compares the thermal performance using Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA) and Heat Distortion Temperature (HDT) of amorphous and semicrystalline polymers with the epoxy thermoset as the reference. The outcome demonstrated that the higher glass filled semi-crystalline polymers were better but there was still thermo-mechanical instability within the morphology at the lower temperatures.