Detection of Distorted Excitation Voltage of Power Transformers Using Vibration Measurements

Power transformers are key components in the electrical energy transmission and distribution. Therefore, special attention is paid to the condition of the transformers, using electrical, chemical, acoustical, and mechanical techniques to assess the transformer health status. However, many diagnostic methods require the transformer to be taken out of service, which can be difficult due to operational restrictions. This paper deals with the detection of distorted excitation voltage of transformers utilizing vibration measurements on the transformer tank. We investigate the applicability of vibrations measurements on the transformer tank to assess changes in the electrical excitation of the transformer. We are using standard vibration measurement equipment for on-load tap changer diagnostic to detect voltage harmonics and dc bias via vibration measurements on the transformer tank. We found that small dc bias in the supply voltage and harmonics with amplitudes below the power quality limits can be detected. These results may be useful to investigate increased transformer sound on-site and to detect other transformer faults with minimum effort on-site