A New Nondestructive Aging Characterization Method for Oil-Paper Insulation Based on the Transmission Characteristics of Complementary Split Ring Resonator

A novel method is proposed for the simple nondestructive characterization of the aging degree of oil-paper insulation materials based on a complementary split ring resonator (CSRR) in this article. Samples of oil-paper insulation are aged under different circumstances by accelerated thermal aging experiment. After that, the traditional characterization methods such as the acid value of insulating oil, the polymerization degree of insulating paper, the Raman spectra test of the insulating oil, microscopic characterization of insulating paper, and dielectric constant of the samples are tested to characterize the aging degree of the samples. In order to find a new way to make the characterization more convenient, microstrip line sensors with CSRR are prepared, and the resonant frequency deviation (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta {f}\,$ </tex-math></inline-formula>) of the sensor loaded with insulating oil and insulating cardboard samples before and after aging are tested to show the effect of aging time and temperature on the aging degree. The experimental results show that the method proposed in this article can reflect the aging trend of oil-paper insulation to a certain extent.