Experimental investigation on dielectric spectroscopy of insulating paper and oil

The dielectric spectroscopy of an impregnated paper and a type of vegetable oil was measured in the frequency domain. In order to investigate the effect of aging on the dielectric response, accelerated thermal aging was conducted on the paper samples and oils samples, respectively. Their dielectric responses were measured at intervals throughout the aging process. Since moisture has a great influence on the permittivity, especially in terms of dielectric loss, the moisture contents of the samples were measured at these time intervals as well. The experimental results showed that the paper samples exhibited increasing dielectric loss and dielectric constant due to the aging process, whereas the tested vegetable oil samples did not show much difference after aging.