Abstract
The time-to-failure for oil-impregnated paper (OIP) insulation is governed by two primary aging mechanisms: electrical and thermal. The electrical life can be represented as an Inverse Power Law, where lifetime is inversely proportional to applied electric field. The process of thermal aging on the other hand is established by Arrhenius Law, which relates the rate of aging exponentially to temperature. Due to thermal aging, the structure of insulation is altered owing to chemical changes like oxidation, polymerization, and cellulose degradation. For life estimation of a service-aged high-pressure gas filled (HPGF) cables, electrical endurance tests are normally performed at controlled voltage levels to estimate the time to breakdown. However, it is equally necessary to investigate how thermal aging influence changes in the electrical life of insulation. Therefore, in this paper, firstly short-term ramped stress tests are carried out on elevated thermal aged OIP samples extracted from already field-aged HPGF to find a rough estimate of breakdown voltages at different temperatures. Then, long-term electro-thermal step stress tests are performed on the samples to establish a correlation of temperature on the electrical life of the OIP insulation. The long-term stress tests produce reliable breakdown statistics and Maximum Likelihood Estimation of Inverse Power Law fitted on 2-parameter Weibull distributed breakdown data indicate a reduction of model parameter, n from 13.61 to 7.38 with an increase in temperature from 45 to 75 °C and a constant shape factor, beta of 1.50. The dissipation factor, tandelta related to the aging also shows an increase with temperature across a wide frequency range and is inversely proportional to the breakdown voltage.
| Original language | English |
|---|---|
| Title of host publication | CEIDP 2022 - 2022 IEEE Conference on Electrical Insulation and Dielectric Phenomena |
| Publisher | Institute of Electrical and Electronics Engineers (IEEE) |
| Pages | 418-421 |
| Number of pages | 4 |
| ISBN (Electronic) | 9781665467957 |
| DOIs | |
| Publication status | Published - 2022 |
| Event | 2022 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2022 - Denver, United States Duration: 30 Oct 2022 → 2 Nov 2022 |
Publication series
| Name | Annual Report - Conference on Electrical Insulation and Dielectric Phenomena, CEIDP |
|---|---|
| Volume | 2022-November |
| ISSN (Print) | 0084-9162 |
Conference
| Conference | 2022 IEEE Conference on Electrical Insulation and Dielectric Phenomena, CEIDP 2022 |
|---|---|
| Country/Territory | United States |
| City | Denver |
| Period | 30/10/22 → 2/11/22 |
Bibliographical note
Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-careOtherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.