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A Field Study of Distribution Transformers provided with Fixed Capacitors in Indian Utilities

P. Valsalal, R. Kannadasan, V. Sankaranarayanan

Abstract


It is a well-known fact that the distribution transformers functioning in rural areas normally have their operating power factors at low level. The presence of predominantly agricultural pump sets and other inductive loads in the rural distribution circuit is the main contributing factor for this situation; lack of consumers awareness about the impacts of such low power factor operation plus their lukewarm response to enhance the reactive power support are among other influencing factors. As a measure to mitigate this situation, the power utilities have provided fixed capacitors across the LT terminals of distribution transformers on a large scale. As this step has been implemented without making detailed studies, a host of problems like the incidence of overvoltages and appearance of ferroresonance with attendant failure of distribution transformers and other LT equipment / devices have been experienced. To find solution to this pressing situation, there is a need to bring all the connected issues to the central stage. Studies are required with an objective to provide guidance (safer) values for the provision of such fixed capacitors across the LT terminals of distribution transformers in rural areas. An attempt has been made in this paper to meet this crucial requirement.

Keywords: Distribution transformers, ferroresonance, fixed capacitors, overfluxing, rural electrical network and self-excitation

 


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References


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