Analysis of the Effect of the Degree of Mixing of Synthetic Ester with Mineral Oil as an Impregnating Liquid of NOMEX ® 910 Cellulose–Aramid Insulation on the Time Characteristics of Polarization and Depolarization Currents Using the PDC Method

Adam Krotowski and Stefan Wolny ()
Additional contact information
Adam Krotowski: Faculty of Electrical Engineering, Automatic Control and Computer Science, Opole University of Technology, Proszkowska 76 B2, 45-758 Opole, Poland
Stefan Wolny: Faculty of Electrical Engineering, Automatic Control and Computer Science, Opole University of Technology, Proszkowska 76 B2, 45-758 Opole, Poland

Energies, 2025, vol. 18, issue 12, 1-22

Abstract: This article continues the authors’ research on NOMEX ® 910 cellulose–aramid insulation saturated with modern electrical insulating liquids, which is increasingly used in the construction of high-power transformers The increase in technical requirements and environmental awareness influences, nowadays, shows that, during the overhaul and modernization of power transformers, petroleum-based mineral oils are increasingly being replaced by biodegradable synthetic esters (oil retrofilling). As a result of this process, the solid insulation of the windings are saturated with an oil–ester liquid mixture with a percentage composition that is difficult to predict. The purpose of the research described in this paper was to test the effect of the degree of mixing of synthetic ester with mineral oil on the diagnostic measurements of NOMEX ® 910 cellulose–aramid insulation realized via the polarization PDC method. Thus, the research conducted included determining the influence of such factors as the degree of mixing of synthetic ester with mineral oil and the measurement temperature on the value of the recorded time courses of the polarization and depolarization current. The final stage of the research involved analyzing the extent to which the aforementioned factors affect parameters characterizing polarization processes in the dielectric, i.e., the dominant dielectric relaxation time constants τ 1 and τ 2 , and the activation energy E A . The test and analysis results described in the paper will allow better interpretation of the results of diagnostic tests of transformers with solid insulation built on NOMEX ® 910 paper, in which mineral oil was replaced with synthetic ester as a result of the upgrade.

Keywords: solid insulation of power transformers; cellulose–aramid insulation; synthetic ester; effect of mixing synthetic ester with mineral oil; dielectric polarization; activation energy; dominant dielectric relaxation time constants (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
References: View references in EconPapers View complete reference list from CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/1996-1073/18/12/3080/pdf (application/pdf)
https://www.mdpi.com/1996-1073/18/12/3080/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:18:y:2025:i:12:p:3080-:d:1676448

Access Statistics for this article

Energies is currently edited by Ms. Agatha Cao

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().