The research of moisture detection in transformer oil based on ultrasonic method

Transformer is one of the most important equipment in the power industry. The moisture content of a power transformer insulation system is a key parameter for the estimation of its aging condition and operation reliability. Therefore detection of the moisture content is a very essential task within power transformer diagnostics. This paper puts forward a moisture detection method in transformer oil based on the ultrasonic transit time difference. The ultrasonic velocity of oil is closer to the water, but has a relatively large difference with ice; the oil-water mixture is frozen to enable the water to become ice in this paper. Because different moisture content will lead to change of propagation time, the moisture content will be obtained from ultrasonic transit time difference. This paper analyses ultrasonic transmit time in the suspension in theory, then verify the theoretical analysis in experimental. The experimental results are in agreement with theoretical analysis. It is clearly showed that the use of ultrasonic on transformer oil moisture detection is feasible.