Analysis of conductance and interfacial polarisation behaviours of silicone rubber based on frequency domain spectroscopy

Abstract

Silicone rubber (SR) is widely used for cable insulation and operates in multi‐stress coupling conditions. Its dielectric properties and ageing performance are the essential factors affecting cable operation. In this study, the frequency domain spectroscopy of unaged SR and SR aged under various conditions is measured. The dielectric responses before and after ageing are analysed in depth by the conjoint analysis via multiple complex planes (permittivity, conductivity, and modulus). Typical conductivity and interfacial polarisation properties, as well as property changes resulting from thermal and tensile ageing, are examined. Experimental results show that tensile ageing promotes conductance and interfacial polarisation ,while thermal ageing shows the opposite effects. Based on the multi‐core model and charge carrier hopping transport model, thermal and tensile ageing mechanisms on the conductance and interfacial polarisation behaviours of SR are demonstrated. Both behaviours exhibit positively correlated changing characteristics, suggesting that the two behaviours may originate from a common process. The carrier transport process, promoted by the tensile effect and slightly suppressed by the thermal effect, is the primary factor and considered an important indicator to evaluate the dielectric properties of SR insulation.