JP2766574B

PURPOSE:To detect oil leakage with accuracy and find an abnormality at its earlier stage by providing an oil level detector, an oil temperature detector and an arithmetic operation means compotes the oil level change and judges that an abnormality occurs when the oil level change ratio is out of a predetermined allowable range. CONSTITUTION:An arithmetic operation means 16 samples an oil level signal and an oil temperature signal periodically from an oil level detector 8 and an oil temperature detector 9 and computes the oil level change ratio with respect to oil temperature changes or the oil quantity change ratio. In this manner, oil leakage is detected by monitoring the oil level or oil quantity change ratio with respect to oil temperature change of an oil-immersed transformer 1 main body. Hence the change in the phenomenon can be detected with a high sensitivity compared with a level decision technique which compares the measured values themselves. There fore oil leakage can be detected at an early stage an what is more, the influence of drastic changes in the oil temperature is small an detection reliability is high.