1. Development and application of new condition assessment methods for power transformers
- Author
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Aschwanden, T., Hassig, M., Fuhr, J., Lorin, P., Der Houhanessian, V., Zaengl, W., Schenk, A., Zweiacker, P., and Piras, A.
- Subjects
polarisation currents ,adaptive threshold ,depolarisation currents ,transfer function measurement ,partial discharge measurement ,online monitoring ,power transformer insulation ,partial discharge detection ,offline diagnosis ,power transformers ,monitoring ,insulation testing ,ageing ,model-based software approach ,transfer functions ,faulty conditions definition ,power transformer testing ,condition assessment methods - Abstract
Recent advances in the application of nontraditional methods and procedures for offline diagnosis and online monitoring of new and service-aged power transformers are discussed. Advanced offline methods are based on the main operational stresses (electrical, mechanical, thermal) and on typical failure modes: measurement of polarisation and depolarisation currents, electrical detection of partial discharges and measurement of the transfer function. A pilot installation of an online monitoring system on a strategically important transformer is described. The measured data of the built-in sensors (e.g. load, temperatures, gas and moisture in oil, overvoltages) are analyzed using a model-based software approach with an adaptive threshold to define faulty conditions