Abstract
Electricity is a vital resource in the 21st century and affect residential, agricultural, industrial and commercial users if interruptions occur. Access to basic electricity is considered as an elementary need in South Africa and around the globe. As a result, International Organisations prioritized access to electricity on their policy agendas. Reliability of electricity supply can face unprecedented challenges due to power outages and other factors such as electricity theft, vandalism of electrical infrastructure, power transformer failures and explosions in a substation. Power outages can result in major interruptions and incur huge costs.
Power transformer is a critical and expensive equipment that plays a huge role in the generation, transmission and distribution of electricity. It is responsible for the efficiency and reliability of power network; hence, it is very important to take care of this asset. The efficiency of power transformers becomes the core target for electricity utilities since they must operate in a competitive market thereby supplying reliable, quality, clean electricity continuously. To achieve these objectives, power transformer’s health must be continuously monitored by conducting relevant maintenance techniques and other condition monitoring techniques as part of asset care program. This process has the capability of sustaining and extending power transformer’s shelf life. Failure to do so may lead to malfunctioning of power transformer, the worst possible case being power transformer failure. Utility loses revenue and engage in unexpected expenditures; businesses lose income and critical customers who depend on life support at home may lose life.
Power utilities in South Africa are faced with power transformer failures in their networks. City Power has been overwhelmed by high number of power outages, some of them caused by power transformer breakdowns. These breakdowns can be frustrating and come at a cost because it causes an outage in the area where power usually takes days to weeks to restore after power transformer breakdown, with the exception of substations with back-up transformers. Once power is restored, the impact of the power transformer failures is usually not explored despite their severity on the grid, businesses and day to day life. It is very crucial that the impact of these outages be investigated, identified and analysed to mitigate how the situation can be avoided in future.
The research was based in Johannesburg, on areas that falls under City Power electrical network. City Power’s Lenasia Service Delivery Centre (SDC) areas are highly affected by these power transformer failures, therefore a case study consisting of 5 cases in this area was developed. The SDC has 10 substations and its electrical infrastructure is aging. The causes included protection malfunction, insulation breakdown, bushings, windings and tap changer failures. Ways to minimize these factors were mitigated in two out of five cases presented. Hypothesis were made to achieve research objectives and Statistical Package for Social Science software was used to analyze the collected data. An estimated R9.21 million and R1.18 million revenues were lost in 11 and 9 days outages, where 4500 and 3285 customers were affected respectively. The study revealed that power transformer breakdowns have negative impact on the entity’s finances and the reliability of electrical network.