A chemical approach to the dielectric aging of fibre-reinforced polymer (frp) insulators

A time-based model for the water-influenced dielectric aging of FRP is presented, using chemical mechanisms to explain the measured increase of the loss tangent and the dielectric constant as well as the inter-phase orientation of the electrical breakdown channel in FRP insulators. Although this hypothesis is founded on artificial and accelerated aging of FRP specimens, it is also representative for real outdoor conditions. The model consists of three phases: 1. water penetration by anomalous diffusion, leading to a weak increase of the dielectric parameters, 2. hydration of generated metal ions, causing a slight decrease of the dielectric constant and a strong increase of both, the loss tangent and the interphase conductivity and 3. a loss of adhesion, resulting in a strong increase of both, the dielectric parameters and the local electrical conductivity.