English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Open

Medium-voltage cross-linked polyethylene (MV-XLPE) cables have an importantrole in the electrical power distribution system. For this reason, the study ofXLPE insulation is crucial to improve cable features and lifetime. Although arelaxational analysis using Thermally Stimulated Depolarization Currents (TSDC)can yield a lot of information about XLPE properties, sometimes its results aredifficult to interpret. In previous works it was found that the TSDC spectrumof cables is dominated by a broad heteropolar peak, that appears just before anhomopolar inversion, but the analysis of the cause of the peak was notconclusive. We have used a combination of TSDC and Isothermal DepolarizationCurrents (IDC) techniques to investigate further this issue. In order todiscard spurious effects from the semiconductor interfaces, samples have beenprepared in certain configurations and preliminary measurements have been done.Then, TSDC experiments have been performed using conventional polarizationbetween 140C and 40C. Also, IDC measurements have been carried out between 90Cand 110C in 2C steps. The TSDC spectra show the broad peak at 95C. On the otherhand, IDC show a combination of power and exponential charge currents.Exponential currents are fitted to a Kohlrausch--Williams--Watts (KWW) model.The parameters obtained present approximately an Arrhenius behavior withE_a=1.32eV, tau_0=3.29e-16s, with a KWW parameter beta=0.8. The depolarizationcurrent calculated from the obtained parameters turns out to match the dominantpeak of TSDC spectra rather well. From the results and given the partiallymolten state of the material, we conclude that the most likely cause of theexponential IDC and the main TSDC peak is the relaxation of molecular dipolesfrom additives incorporated during the manufacturing process.

Identification of dipolar relaxations in dielectric spectra of mid--voltage cross--linked polyethylene cables