Research on Charge Accumulation Characteristics by PEA Method and Q(t) Method

This article reports the evaluation system of the insulating properties based on the pulsed electro-acoustic (PEA) method and the current integration charge <inline-formula> <tex-math notation="LaTeX">$Q(t)$ </tex-math></inline-formula> method. According to the basic principles of the methods, the relationship between the charge ratio and dielectric relaxation time in <inline-formula> <tex-math notation="LaTeX">$Q(t)$ </tex-math></inline-formula> data is first derived, by which a new method is proposed to calculate the material conductivity. By further analyzing the charge results of different materials, it is pointed out that the PEA method focuses on the related characteristics of the net charge distribution captured by deep traps, while the <inline-formula> <tex-math notation="LaTeX">$Q(t)$ </tex-math></inline-formula> method reflects the changing process of the total charge amount and related characteristics. No single method can completely analyze all the charge characteristics of the material, and thus the necessity of the combination of the two methods is determined. Meanwhile, based on the theoretical derivation and experimental results, it is indicated that when the charge ratio of <inline-formula> <tex-math notation="LaTeX">$Q(t)$ </tex-math></inline-formula> data exceeds 2, the electrical state inside the sample basically stabilizes. At this stage, the distorted electric field can be analyzed by the PEA method, and the <inline-formula> <tex-math notation="LaTeX">$Q(t)$ </tex-math></inline-formula> method can calculate the leakage current, dielectric relaxation time, and conductivity. Therefore, the combination of the two methods can provide a more reasonable assessment for the insulation property and state.