Uncertainty Analysis of Loss Measurement for Large-Scale Power Transformer

To guide the selection of measuring devices for loss measurement of large-scale power transformers and implement accurate loss measurement,the factors leading to the uncertainty during the loss measurement of large-scale power transformers are analyzed.Through quantitative calculation of uncertainties due to these factors,the uncertainties caused by single factors are synthesized to attain the measurement uncertainty of the whole measuring system.Based on uncertainty analysis of loss measurement,it is found that the phase measurement accuracy of the measuring system is the upmost factor affecting the measurement uncertainty.The uncertainties of loss measurements by different measuring systems are quantitatively analyzed and compared,and the results show that the measuring system composed of CT and PT with 0.01 accuracy grade and worked in with Fluke Norma 5000 power analyzer(or power analyzers with similar performances) is suitable to loss measurement for large-scale power transformers,and the uncertainty of loss measurement for large-scale power transformers can be controlled to be lower than 2%.