Cable aging estimation method combining step-by-step withstand voltage method and isothermal relaxation current method

Abstract

The invention discloses a cable aging estimation method combining a step-by-step withstand voltage method and an isothermal relaxation current method. The cable aging estimation method includes the following steps of step-by-step withstand voltage method testing and isothermal relaxation current method testing. According to the cable aging estimation method, on one hand, a result obtained through the isothermal relaxation current method is used as a tendency judgment and used for judging a rough cable aging degree, and on the other hand, a result obtained through the withstand voltage method is used as a concrete judgment, and then the remaining service life of a cable can be inferred. In other words, the result obtained through the isothermal relaxation current method is the tendency judgment, the result obtained through the withstand voltage method is the concrete judgment, and hereby the cable aging situation can be estimated by combining a destructive test and a nondestructive test to determine whether the cable needs to be replaced or not. Accordingly, one-sided reflection of a single method on an estimation result is avoided, the result can be higher in reference value, and the cable aging estimation method can have guidance significance on power grid transformation and operation, maintenance and detection of the cable.

Description

technical field [0001] The invention relates to the technical field of testing the insulation performance of cross-linked polyethylene cables, in particular to a method for quickly testing the insulation performance of cross-linked polyethylene cables combined with a step-by-step withstand voltage method and an isothermal relaxation current method. Background technique [0002] Since the 1980s, cable technology at home and abroad has developed rapidly, and traditional oil-filled cables have been gradually replaced by XLPE cables manufactured by three-layer co-extrusion production technology. Compared with the former, the latter has excellent properties such as no oil supply, fire prevention, simple installation and maintenance, and good mechanical and electrical performance, and its application range is gradually expanding. Taking China as an example, XLPE cables are widely used in big cities such as Shanghai, Beijing, and Guangzhou. It is of great significance to fully und...

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Problems solved by technology

The former mainly depends on the dielectric constant of each medium, while the latter mainly depends on the resistivity of the material. The difference in principle between the two makes it difficult to find the weak link of insulation under AC voltage in the DC voltage test.

[0004] In addition, the DC withstand voltage test has a cumulative effect on the insulation, which will accelerate the aging of the cable and shorten the service life of the cable

Therefore, XLPE cables do not use the DC withstand voltage test

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