Dielectric response of SRBP as a function of oil and oil/moisture absorption.

Although insulation based on synthetic resin bonded paper (SRBP) is regarded as an old technology, insulation systems based on this material are still used within the electrical power industry. Much of these are coming to the end of their expected 40 year asset life and techniques for assessing the condition need to be developed such that an effective replacement strategy can be put in place. In this paper, dielectric spectroscopy is to be used to characterize the condition of SRBP. The dielectric response of synthetic resin bonded paper (SRBP) as a function of oil content, and oil plus absorbed moisture is presented over the temperature range 30 degC to 60 degC, and frequency range 5 mHz to 100 kHz. The spectra will be analysed using the Havriliak and Negami semi-empirical form of the Debye dispersion relations, (including a conduction term). The temperature and moisture dependence of the conduction will be discussed, and the relaxation times (tau) for the dispersion mechanisms will then be evaluated for the range of temperatures used