Aging State Evaluation of Oil-Paper Insulation Based on Electro-Mechanical Impedance Technology

The oil-paper insulation’s aging can deteriorate the mechanical and electrical performance of the electrical power device; thus, it is necessary to evaluate the aging state of oil-paper insulation. Based on the electro-mechanical impedance technology, a novel aging state evaluation method of oil-paper insulation is proposed in this letter, which utilizes the piezoelectricity caused by the insulating paper attached to the piezoelectric material (PZT). The electro-mechanical model of the paper-PZT system is established considering the electric-vibration coupling effect and its characteristics are analyzed using the principle of stationary action. The insulating paper with different aging states, indicated by the degree of polymerization (DP), is selected to obtain the impedance characteristics of the paper-PZT system. The experimental results show the impedance amplitudes of the paper-PZT system increase with the aging degree, which can help in the nondestructive aging evaluation of the oil-paper insulation.