{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T02:17:39Z","timestamp":1773281859889,"version":"3.50.1"},"reference-count":41,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2018,7,6]],"date-time":"2018-07-06T00:00:00Z","timestamp":1530835200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"UNITEN R&amp;D","award":["U-SN-CR-17-07"],"award-info":[{"award-number":["U-SN-CR-17-07"]}]},{"name":"UNITEN BOLD Grant","award":["10289176\/B\/9\/2017\/41"],"award-info":[{"award-number":["10289176\/B\/9\/2017\/41"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Monitoring the condition of transformer oil is considered to be one of the preventive maintenance measures and it is very critical in ensuring the safety as well as optimal performance of the equipment. Various oil properties and contents in oil can be monitored such as acidity, furanic compounds and color. The current method is used to determine the color index (CI) of transformer oil produces an error of 0.5 in measurement, has high risk of human handling error, additional expense such as sampling and transportations, and limited samples can be measured per day due to safety and health reasons. Therefore, this work proposes the determination of CI of transformer oil using ultraviolet-to-visible (UV-Vis) spectroscopy. Results show a good correlation between the CI of transformer oil and the absorbance spectral responses of oils from 300 nm to 700 nm. Modeled equations were developed to relate the CI of the oil with the cutoff wavelength and absorbance, and with the area under the curve from 360 nm to 600 nm. These equations were verified with another set of oil samples. The equation that describes the relationship between cutoff wavelength, absorbance and CI of the oil shows higher accuracy with root mean square error (RMSE) of 0.1961.<\/jats:p>","DOI":"10.3390\/s18072175","type":"journal-article","created":{"date-parts":[[2018,7,6]],"date-time":"2018-07-06T10:55:44Z","timestamp":1530874544000},"page":"2175","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":51,"title":["UV-Vis Spectroscopy: A New Approach for Assessing the Color Index of Transformer Insulating Oil"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5750-2293","authenticated-orcid":false,"given":"Yang Sing","family":"Leong","sequence":"first","affiliation":[{"name":"Institute of Power Engineering, College of Engineering, Universiti Tenaga Nasional, Kajang 43000, Selangor, Malaysia"}]},{"given":"Pin Jern","family":"Ker","sequence":"additional","affiliation":[{"name":"Institute of Power Engineering, College of Engineering, Universiti Tenaga Nasional, Kajang 43000, Selangor, Malaysia"}]},{"given":"M. Z.","family":"Jamaludin","sequence":"additional","affiliation":[{"name":"Institute of Power Engineering, College of Engineering, Universiti Tenaga Nasional, Kajang 43000, Selangor, Malaysia"}]},{"given":"Saifuddin","family":"M. Nomanbhay","sequence":"additional","affiliation":[{"name":"Institute of Power Engineering, College of Engineering, Universiti Tenaga Nasional, Kajang 43000, Selangor, Malaysia"}]},{"given":"Aiman","family":"Ismail","sequence":"additional","affiliation":[{"name":"Institute of Power Engineering, College of Engineering, Universiti Tenaga Nasional, Kajang 43000, Selangor, Malaysia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1030-7554","authenticated-orcid":false,"given":"Fairuz","family":"Abdullah","sequence":"additional","affiliation":[{"name":"Institute of Power Engineering, College of Engineering, Universiti Tenaga Nasional, Kajang 43000, Selangor, Malaysia"}]},{"given":"Hui Mun","family":"Looe","sequence":"additional","affiliation":[{"name":"Tenaga Nasional Berhad (TNB) Research Sdn. Bhd., Bandar Baru Bangi, Kajang 43000, Selangor, Malaysia"}]},{"given":"Chin Kim","family":"Lo","sequence":"additional","affiliation":[{"name":"Tenaga Nasional Berhad (TNB) Research Sdn. Bhd., Bandar Baru Bangi, Kajang 43000, Selangor, Malaysia"}]}],"member":"1968","published-online":{"date-parts":[[2018,7,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"777","DOI":"10.1109\/TIA.1980.4503871","article-title":"Transformer fault diagnosis by dissolved-gas analysis","volume":"IA-16","author":"Kelly","year":"1980","journal-title":"IEEE Trans. Ind. Appl."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1109\/MEI.2002.1161455","article-title":"Review of condition assessment of power transformers in service","volume":"18","author":"Wang","year":"2002","journal-title":"IEEE Electr. Insul. Mag."},{"key":"ref_3","unstructured":"Gray, I. (2017, November 07). A Guide to Transformer Oil Analysis. 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