Non-destructive method for evaluating cable aging and operating cable status

Abstract

The invention discloses a non-destructive method for evaluating the cable aging and operating cable status. According to the method, isothermal relaxation current characteristics of two types of polarized XLPE cable samples and cable samples under different operating years in the depolarization process are analyzed, relevant parameters such as the trap distribution characteristic are obtained, andthe theoretical support is provided for insulation status analysis of polymers. The method is advantaged in that the insulation and aging status of cables can be provided, the residual life of the cables can be obtained without reference to the operating history of the cables, through non-destructive measurement, not only can insulation performance of the cables be evaluated, but also internal space charges and trap distribution characteristics can be obtained, and the method can be utilized to evaluate insulation properties of the cables.

Description

technical field [0001] The invention belongs to the field of electrical insulation, and relates to a non-destructive method for evaluating cable aging and operating cable status, in particular to an evaluation method combined with relevant parameters such as the distribution characteristics of insulation internal traps. Background technique [0002] The aging of cable insulation is an important factor affecting the electrical performance of cables, so the evaluation of the aging state and insulation life of cables in actual operation has always been the focus of attention in the industry. [0003] In the prior art, the withstand voltage method and the dielectric loss factor method are commonly used experimental methods for evaluating cross-linked polyethylene (XLPE) cables. Among them, first of all, the withstand voltage method is a method to directly judge the cable insulation performance, which can accurately evaluate the cable life, but this method is difficult to accurat...

AI Technical Summary

Problems solved by technology

Among them, first of all, the withstand voltage method is a method to directly judge the cable insulation performance, which can accurately evaluate the cable life, but this method is difficult to accurately distinguish the influence of distributed defects and concentrated defects on the cable life, and the resistance If the discharge time of the cable core is not enough after pressing, its residual charge will affect the measurement of insulation resistance

Moreover, during the experiment, this method needs to be constantly compared with the parameters of the new cable, and the data processing is cumbersome.

Secondly, the dielectric loss factor method is mainly based on harmonic analysis to measure the dielectric loss angle δ. Because the power frequency signal of the power system is affected by various factors, its fundamental frequency will fluctuate to a certain extent, which is not always the ideal 50Hz. , and the test and analysis of the dielectric loss angle δ based on the harmonic analysis method will also produce large errors due to the phenomenon of "spectrum leakage"

These shortcomings limit the popularization and application of these two methods.

Images