An on-line hydroturbine temperature monitoring system is introduced, which is composed of a TCD-48 digital temperature inspection instrument, RS-485 bus and PC monitoring software. The TCD-48 digital temperature inspection instrument directly acquires the temperatures via 48 channels and sends the data to the industrial PC via RS-485 bus for data display, storage and analysis. The monitoring system carries out the fitting analysis based on the acquired data to realize the online temperature monitoring of hydroturbine components. The operator can find the temperature abnormality in real time an...