A case study of maintenance and condition monitoring of the power transformers

Maintenance Optimization

This research is a case study of the maintenance optimization for power transmission systems processes and particularly transformers of GRIDCo. It is therefore imperative to combine both qualitative and quantitative techniques. The quantitative technique involves a participant observation of the operations at GRIDCo and a survey of human subjects who expressed their views of the Maintenance Optimization process.

It also involves analysis of data on a sample of products returned for after sales service and their corresponding quality control check procedures and data prior to their being released.

The task of finding the optimal balance of preventive and corrective maintenance is approached as a multicriteria optimization problem. On one hand, we have the customers’ demands for power delivery and on the other hand we have the maintenance cost for the transmission equipment.

In the optimization equipment failure and the consequent total customer interruption cost is used as the measure of system reliability performance from the customer perspective.

The maintenance costs are closely related to the analyzed network, its components, structure and available resources.

The non-human subjects in the qualitative study involve a descriptive narrative of the Maintenance Optimization for Power Transmission Systems procedure or protocol as well as the same descriptive narrative of the reality of the actual maintenance process.

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Data on transmission systems were sampled and analysed. Yin (2009) asserts that a case study is an empirical inquiry about a contemporary phenomenon, that is, a case, set within its real-world context especially when the boundaries between phenomenon and context are not clearly evident.

Case studies involve an up-close or in-depth understanding of a single or small number of cases, set in their real-world contexts. The closeness aims to produce an invaluable and deep understanding, which results in new learning about real-world behaviour and its meaning.

Source data

Two main sources of data namely, the primary and secondary sources of data were used for the case study. In this context, the researcher acquired primary data via collection of original primary materials from field personnel and equipment manuals.

Part of the research work carried out at Obuasi, Buipe, Aflao, Achimota, Winneba and New Substations investigated the maintenance records on transformers at these locations prior to the failures of transformers at the said substations. This was aimed at verifying the adequacy or otherwise of time-based maintenance techniques in the maintenance of transmission equipment.

This explains how costly corrective maintenance can result from ineffective planned preventive maintenance on transmission equipment.

The results of the research work exposed the inadequacy of time based maintenance which makes reliability of power supply vulnerable to unexpected equipment failures. Electricity consumers in Winneba and its environs had to suffer power cuts for about one month after the failure of the transformer before it was replaced.

Though best practices cannot entirely prevent the occurrence of every equipment failure in GRIDCo, the research work also revealed that early warnings and proactive maintenance can reduce the probability of catastrophic failures.