An Offline and Online Approach to the OLTC Condition Monitoring: a Review


Transformer failures have a significant cost impact on the operation of an electrical network. In many utilities, transformers have been operating for many years past their expected usable life. As power demand has surged, transformers in some areas are being loaded beyond their rated capacity to meet the demand. One of the vital components in a transformer is the on-load tap changer (OLTC), which regulates the voltage in the distribution network. This study aims to review several condition-monitoring techniques (online and offline) that can monitor the health of the OLTC and assure the safety of the transformer’s OLTC from irreparable damage by detecting the defect at an earlier stage, which is preceded by the specification of typical faults. This paper also discussed the common faults of the OLTC and the root causes of these faults. The OLTC is prone to mechanical faults due to its frequently changing mechanism in the tap operation. The OLTC are also prone to oil as well as thermal faults. As a result, it is critical to monitor OLTC conditions while they are in use. Proper management of condition monitoring (CM) for the OLTC is useful and necessary to increase availability and achieve optimised operating. Condition monitoring (CM) and diagnostics methods (DM) have been developing since the 1950s. CM and DM have been implemented to diagnose and detect an incipient fault, especially for the OLTC. Many techniques, online and offline, are being used to monitor the condition of the OLTC to prevent failure and minimize outages. These DM and CM will prolong the operational cycle and avoid a major disaster for the OLTC, which is an unfavorable scenario.

Divisions: College of Business and Social Sciences > Aston Business School
College of Business and Social Sciences > Aston Business School > Operations & Information Management
Additional Information: Funding Information: The authors would like to acknowledge the financial support provided by Tenaga Nasional Berhad Seeding Fund with the project code: U-TD-RD-21-07, that is managed by UNITEN R&D Sdn. Bhd. Funding Information: The authors would like to acknowledge the publication support through TNB Seeding Fund provided by Tenaga Nasional Berhad (TNB), Project No. U-TD-RD-21-07. Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (
Publication ISSN: 1996-1073
Last Modified: 29 Nov 2023 13:29
Date Deposited: 07 Feb 2023 18:10
Full Text Link: 10.3390/en15176435
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
https://www.mdp ... 1073/15/17/6435 (Publisher URL)
PURE Output Type: Review article
Published Date: 2022-09-02
Accepted Date: 2022-08-16
Authors: Ismail, Firas B.
Mazwan, Maisarah
Al-Faiz, Hussein
Marsadek, Marayati
Hasini, Hasril
Al-Bazi, Ammar
Yang Ghazali, Young Zaidey



Version: Published Version

License: Creative Commons Attribution

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