The velocity measurement of cooling gas in SF6 gas transformer by reflective ultrasonic wave method

Abstract

The improvement of the cooling-gas velocity distribution over the coil windings in SF6 gas transformer is very important to achieve high quality for designing. In this paper, the application results of the reflective-type ultrasonic wave method to measure the cooling gas distribution in the SP6 gas transformer are reported. This measurement can be performed without disturbance of the gas flow by the presence of the sensors, and this method is demonstrated to be more effective than the conventional fluid velocity measuring method. In this measurement, the velocity of gas flow at some locations in the transformer was not proportional to the volume of the input gas flow. It can be divided into three patterns corresponding to the location as follows. (a) Gas velocity increases with the increase of the input gas flow amount. (b) Gas velocity is constant regardless of the increase of the input gas flow amount. (c) Gas velocity decreases with the increase of the input flow in the first, and changes to increase with the further increase of the input flow. These characteristics are compared with the computational results of gas flow analysis. © 1998 Scripta Technica. Electr Eng Jpn, 122(3): 1–9, 1998