AC Breakdown Voltage of 50-Year-Old Service Aged Hydro Power Generator Stator Bars
DOI:
https://doi.org/10.5324/nordis.v27i1.4714Abstract
Randomly selected generator bars from a 50-year-old Norwegian hydro power generator were examined in this work. Typical non-destructive tests, as partial discharge and dissipation factor measurements were initially performed at both 50 Hz and 0.1 Hz. Then, the AC breakdown strength of the epoxy/mica/glass fibre reinforced bar insulation was measured by gradually increasing the voltage in steps of 5 kV with duration of 1 min until breakdown occurred. The field graded terminations were soaked in transformer oil during breakdown testing to prevent external surface flashovers. The AC breakdown voltage ranged between 60 kV and 75 kV, which corresponds to 8-10-fold the service voltage of 7.4 kV. No significant difference in breakdown voltage was observed between bars being located close to the high voltage or neutral terminal during service. This indicates minor degradation caused by the AC service stress, even after 50 years in service. No correlations were found between the measured breakdown voltage and the diagnostic partial discharge activity and dissipation factor measurements.
Downloads
Downloads
Published
Issue
Section
License
Copyright (c) 2022 Torstein Aakre, Erling Ildstad
This work is licensed under a Creative Commons Attribution 4.0 International License.
Proceedings of the Nordic Insulation Symposium licenses all content of the journal under a Creative Commons Attribution (CC-BY) licence. This means, among other things, that anyone is free to copy and distribute the content, as long as they give proper credit to the author(s) and the journal. For further information, see Creative Commons website for human readable or lawyer readable versions.
Authors who publish with this journal agree to the following terms:
1. Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
2. Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
3. Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).
