Technical problems encountered with the laser induced pressure pulse method in studies of high voltage cable insulators

The laser induced pressure wave propagation method is often used to measure the space charge distribution in solid insulators. This method gives rise to many advantages, so it is widely used both in industrial and in research laboratories. However, it is necessary to take some precautions before treating induced signals in order to minimize calculation errors. Here, some quantitative information about the effects of approximations and the technical problems arising from this method used to study cable insulators are presented. Data from semiconductor/polyethylene samples have been obtained. Some recommendations defining an appropriate experimental protocol of space charge measurement in high voltage cable insulators are given.