Abstract
The dielectric and mechanical properties of Type II machine insulation after accelerated thermal ageing at 230° C have been investigated. Dielectric spectroscopy and dynamic mechanical analysis (DMA) were used to assess the insulation system's response to thermal ageing. The dielectric measurements indicate a reduction in dielectric losses with ageing and how the delamination can affect the measurements. The DMA results reveal a decrease in the storage modulus, indicating potential degradation of the epoxy resin and polymer matrix. The observed delamination and breaking of samples highlight the compromised structural integrity of the insulation.