In this paper, we propose online monitoring systems for uninterrupted noncontact temperature measurement and detection of overheated water-cooled rotor poles of all ten hydrogenerators in the hydropower plant Djerdap 2 on Danube. The proposed stand-alone monitoring systems are based on remote infrared measurement and recognition of hot pole surface of the rotor. The main parts of each system are measuring device, industrial PC with the SCADA interface, virtual instrument, and related database. The measuring device is installed in front of the generator and consists of optical, analog, and processing units. The novel applied method of measuring remote temperature is based on the measurements of emission of infrared radiation from rotor poles in motion. Ten systems, for all ten generators in the power plant, are connected to SCADA. They are very useful for continuous maintenance without work interruption, and have vital roles in power plant such as fault detection and keeping electric power generating safe, preventive maintenance, and avoidance of damaging to rotor poles. These monitoring systems are also useful for the modern maintenance approach such as condition-based maintenance without generators' work interruption and better planned and preventive maintenance in the power plant. In this paper, we also present the use of the measurement system in novel heat run test on a rotor. This test is performed under the real exploitation condition.