An Investigation into Protection Integrity of Distribution Transformers - A Case Study

This paper investigates protection integrity of distribution transformers in Ghana. The purpose of the study was to find the main causes of distribution transformer failures in Ghana. The study was conducted in the Ashanti East Region, one of the operational areas of Electricity Company of Ghana ECG with high incidence of distribution transformer burnouts. Data on status of protection systems on 676 distribution transformer stations were taken and analyzed. It was found that protection integrity at distribution substation is riddled by indiscriminate use of copper links to replace blown HRC fuses and high ground resistance. The study clarifies why distribution transformers with lower power ratings are more vulnerable to abuse of protection systems than distribution transformers with higher rated powers. The paper reports on the investigation and proposes alternative solutions in mitigating the problem. Although the background work of the study is restricted to Ghana, the applicability and importance of the work would be useful to the scientific community.