International Journal of Engineering Trends and Technology Volume 70 Issue 3, 75-84, March, 2022 ISSN: 2231 – 5381 /doi:10.14445/22315381/IJETT-V70I3P209 © 2022 Seventh Sense Research Group® This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Original Article Application of the FMECA Tool in the Identification of Causes of Faults in Distribution Transformers in Cameroon: Case of the Buea Sub-Area Network Wirnkar Basil Nsanyuy 1 , Chu Donatus Iweh 2 , Nde Donatus Nguti 3 , Felix Nkellefack Tapang 4 , Emmanuel Tanyi 5 1 PhD candidate/scholar, Department of Electrical and Electronic Engineering, Faculty of Engineering and Technology, University of Buea, Cameroon., P.O. Box 63 Buea, Cameroon 2 PhD candidate, Regional Centre for Energy and Environmental Sustainability (RCEES), School of Engineering, University of Energy and Natural Resources, P.O. Box 214, Sunyani, Ghana. 3 Co-supervisor, Department of Electrical and Electronic Engineering, Faculty of Engineering and Technology, University of Buea, Cameroon., P.O. Box 63 Buea, Cameroon 4 Electrical Engineer, Power Utility Company (ENEO Cameroon S.A) Buea, Cameroon 5 Professor & Supervisor, Department of Electrical and Electronic Engineering, Faculty of Engineering and Technology, University of Buea, Cameroon., P.O. Box 63 Buea, Cameroon 1 wirnkar.basil@ubuea.cm, 2 iwehdona@mail.com, 3 nde.nguti@ubuea.cm Abstract - The reliability of the distribution system is dependent on system components such as transformers. When faults occur in the distribution transformers, especially when they connect the power system to critical loads such as telecommunication systems, airports, hospital railways, etc., the failure could be catastrophic as it brings about material and economic losses to the utility company. This situation is even more serious in developing countries with mostly radial network topology. The energy utility company in Cameroon (ENEO Cameroon) has been facing several power outages on the distribution network caused by the failures of distribution transformers, and this has resulted in severe economic impacts not only on ENEO but extends on damaging of customers’ equipment. The rationale of this research is to identify distribution transformer root causes of failures in the Buea distribution network. The area chosen for this study is Buea, a sub-area of the Southern Interconnected Grid (SIG) in Cameroon. The FMECA procedure was applied on the distribution transformers to identify the failure modes, effects and criticality analysis. The study found that the failure rate in Buea from 2019-2021 was 15% and on averagely 5% annually. The FMECA results revealed that windings failure and insulation failure were the most probable causes of failures in Buea, while vandalism, bushings and the core were also to be carefully monitored to prevent equipment failure. Keywords - Criticality analysis, ENEO, Reliability, radial network, SIG. I. INTRODUCTION Access to reliable, robust and affordable electricity supply is a prerequisite for the socio-economic development of any society[1]. It is, therefore, a precondition for the operation of industry, transportation, health care systems, education and in some high-value applications like computing and telecommunications [2]. The conventional power infrastructure is described by isolated components of generation, transmission, substation and distribution. The stability and reliability of electrical power systems are greatly influenced by system components. Amongst these components are transformers which play a central role in the transformation of voltage levels. The distribution transformers serve as the final connection between the power system and low voltage consumers. The failure of a distribution transformer is costly to the utility company and can also damage the equipment of connected clients. For example, one blackout in North Eastern USA and Canada caused estimated financial damage amounting to 6 billion dollars in 2003[3]. Unlike developed countries that are connected by the mesh network, developing countries like Cameroon are connected by the radial network architecture imposed by a lack of investments[4]. One of the drawbacks of this radial network architecture is that the addition of a new load necessitates the resizing or replacement of the distribution transformer in that line in order to avoid overloading[5]. ENEO Cameroon has incurred lots of financial losses due to distribution transformer failures. From 2019 to 2021, Buea recorded 24 transformer failures, while in 2020, ENEO lost 500 distribution transformers nationwide [4]. Because of the disastrous economic impact of distribution transformer