{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:30:29Z","timestamp":1760236229542,"version":"build-2065373602"},"reference-count":45,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2021,11,2]],"date-time":"2021-11-02T00:00:00Z","timestamp":1635811200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100008561","name":"Universiti Tenaga Nasional","doi-asserted-by":"publisher","award":["RJO10517844\/054"],"award-info":[{"award-number":["RJO10517844\/054"]}],"id":[{"id":"10.13039\/501100008561","id-type":"DOI","asserted-by":"publisher"}]},{"name":"BOLD Refresh Publication Fund 2021","award":["J5100D4103"],"award-info":[{"award-number":["J5100D4103"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The color of transformer oil can be one of the first indicators determining the quality of the transformer oil and the condition of the power transformer. The current method of determining the color index (CI) of transformer oil utilizes a color comparator based on the American Society for Testing and Materials (ASTM) D1500 standard, which requires a human observer, leading to human error and a limited number of samples tested per day. This paper reports on the utilization of ultra violet-blue laser at 405- and 450-nm wavelengths to measure the CI of transformer oil. In total, 20 transformer oil samples with CI ranging from 0.5 to 7.5 were measured at optical pathlengths of 10 and 1 mm. A linear regression model was developed to determine the color index of the transformer oil. The equation was validated and verified by measuring the output power of a new batch of transformer oil samples. Data obtained from the measurements were able to quantify the CI accurately with root-mean-square errors (RMSEs) of 0.2229 for 405 nm and 0.4129 for 450 nm. This approach shows the commercialization potential of a low-cost portable device that can be used on-site for the monitoring of power transformers.<\/jats:p>","DOI":"10.3390\/s21217292","type":"journal-article","created":{"date-parts":[[2021,11,2]],"date-time":"2021-11-02T22:17:23Z","timestamp":1635891443000},"page":"7292","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Color Index of Transformer Oil: A Low-Cost Measurement Approach Using Ultraviolet-Blue Laser"],"prefix":"10.3390","volume":"21","author":[{"given":"Muhamad Haziq","family":"Hasnul Hadi","sequence":"first","affiliation":[{"name":"Institute of Sustainable Energy, Universiti Tenaga Nasional, Kajang 43000, Malaysia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5703-1735","authenticated-orcid":false,"given":"Pin Jern","family":"Ker","sequence":"additional","affiliation":[{"name":"Institute of Sustainable Energy, Universiti Tenaga Nasional, Kajang 43000, Malaysia"}]},{"given":"Hui Jing","family":"Lee","sequence":"additional","affiliation":[{"name":"Institute of Power Engineering, Universiti Tenaga Nasional, Kajang 43000, Malaysia"}]},{"given":"Yang Sing","family":"Leong","sequence":"additional","affiliation":[{"name":"Institute of Power Engineering, Universiti Tenaga Nasional, Kajang 43000, Malaysia"},{"name":"Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built Environmental, Universiti Kebangsaan Malaysia (UKM), Bangi 43600, Malaysia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8367-4112","authenticated-orcid":false,"given":"Mahammad A.","family":"Hannan","sequence":"additional","affiliation":[{"name":"Institute of Sustainable Energy, Universiti Tenaga Nasional, Kajang 43000, Malaysia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9637-6867","authenticated-orcid":false,"given":"Md. Zaini","family":"Jamaludin","sequence":"additional","affiliation":[{"name":"Institute of Power Engineering, Universiti Tenaga Nasional, Kajang 43000, Malaysia"}]},{"given":"Mohd Adzir","family":"Mahdi","sequence":"additional","affiliation":[{"name":"Wireless and Photonics Networks Research Centre, Faculty of Engineering, Universiti Putra Malaysia (UPM), Serdang 43400, Malaysia"}]}],"member":"1968","published-online":{"date-parts":[[2021,11,2]]},"reference":[{"unstructured":"Jan, S.T., Afzal, R., and Khan, A.Z. (2015, January 1\u20132). Transformer Failures, Causes & Impact. Proceedings of the International Conference Data Mining, Civil and Mechanical Engineering (ICDMCME\u20192015), Bali, Indonesia.","key":"ref_1"},{"doi-asserted-by":"crossref","unstructured":"Alshehawy, A.M., Mansour, D.E.A., Rezk, A., and Ghali, M. (2016, January 27\u201329). Impact of thermal aging of transformer oil on UV-Vis optical spectrum and dielectric properties. 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