Oil-immersed transformer BWR-04-06WTemperature indicator

As the oil temperature on the top of a large capacity transformer lags behind the winding temperature significantly,switching the cooling system of a transformer by a winding temperature signal can improve the behavior of a transformer promptly and efficiently.Therefore a large capacity transformer usually switches its cooling system by using a winding temperature signal.But direct measurement of the winding temperature of a power transformer has resulted in a problem of high voltage isolation technologically.As a result at present the technique of thermal simulation based on IEC 354 Loading Guide for Oil-immersed Transformers is widely used at home and abroad in measuring the winding temperature of transformers indirectly. According to IEC 354,the winding temperature of atransformer（Tw）is the sum of the oil temperature（To）on the top of a transformer and temperature difference between copper and oil（Two）,i.e.,Tw=To+Two;of which the oil temperature can be obtained by measurment using a pressure thermometer,but the data on the temperature difference between copper and oil that varies with transformer load has to be obtained through thermal simulation.