Digital on-line monitoring device for oil level of transformer expansion tank

The invention relates to a transformer expansion tank oil level digital on-line monitoring device which comprises an oil level detection device, an intelligent management platform, an intelligent gateway and a serial port server, and the intelligent gateway and the serial port server are used for connecting the oil level detection device and the intelligent management platform. A connecting plate and an ultrasonic oil level sensor are arranged on the left side and the right side of the oil level detection device respectively, a radio frequency antenna is arranged above the connecting plate, a first mounting seat or a second mounting seat is arranged on the left side of the connecting plate, and the oil level detection device is mounted through the first mounting seat or the second mounting seat. The oil level detection device is in signal connection with the intelligent gateway and is used for sending acquired data information; the intelligent gateway is in signal connection with the serial server and is used