Overview

This document provides an efficient and reliable procedure to test the internal electric field in the insulating materials used for high-voltage applications, by using of the pressure wave propagation (PWP) method. It is suitable for a planar and/or coaxial geometry sample with homogeneous insulating materials and an electric field higher than 1 kV/mm, but it is also dependent on the thickness of the sample and the pressure wave generator. The test procedure described in this document is not suitable for measuring conductive materials or insulating materials that do not have a planar or coaxial sample geometry. High-voltage insulation structures, particularly high-voltage direct-current cables and capacitors, etcetera, are subject to charge accumulation, which can lead to electrical breakdown if the electric field generated by the charges exceeds the threshold for electrical breakdown. With the trend toward multiple energy generation facilities, particularly renewable energy facilities such as wind or solar generators, more cables are being used to connect these facilities to the grid and to distribute electrical energy between countries. Thus a standardized method is needed for the materials of the cables and even the construction of these cables - taking into account the electrodes or the connections between cables - in order to determine how the internal electric field can be characterized. Measuring the internal electric field would make it possible to compare materials and help establish threshold values for the internal electric field in high-voltage applications in order to minimize the risk of breakdown. The pressure wave propagation (PWP) method has been used by many researchers in order to measure the space charge distribution and the distribution of the internal electric field in insulators. However, since the test equipment is independently developed with minor differences by researchers worldwide, it is difficult to compare the measurement results of the various devices. The method described in this standard provides a reliable basis for comparing the various test results obtained by different laboratories, thus helping to avoid misinterpretations. The method is suitable for planar plate samples as well as coaxial samples with homogeneous insulating materials. IEC has established a project team to develop a method for PWP measurement.

Responsible national committee

DKE/K 183 - Bewertung und Qualifizierung von elektrischen Isolierstoffen und Isoliersystemen