Different aspects of testing of the resistance of polyethylene materials to the inception of treeing and to the treeing breakdown

The inception and breakdown parameters of electrical treeing (ET) were investigated in LDPE (low-density polyethylene) samples within the framework of the CIGRE recommendations for preparation of samples and for treeing inception measurements. The present results indicate different abilities of polyethylene to resist either inception of growth of trees, which can be related to the morphology of the material sample along the interelectrode distance. Life curves obtained for different materials are dependent on the size of dielectric stressed during the test. Therefore, it appears to be difficult to characterize the long-term behavior of LDPE due to tree growth, as no relation has been yet found which allows correlation of the results obtained by adopting samples with different geometry