Measurement of Excitation Winding Temperature on Synchronous Generator in Rotation Using Infrared Thermography

A new measurement method for infrared (IR) surface temperature measurement of excitation winding in rotation is presented. The method is experimentally verified on a 400-kVA salient pole synchronous generator. This method uses an industrial IR thermometer which represents an alternative to expensive fast IR thermometers or cameras. The target application of this method is the determination of the dynamic limit in the P - Q diagram of a synchronous generator due to excitation winding overheating. The measurement error model which shows the way how to minimize measurement error has also been derived. The effect of the interpolar surface can be cancelled if the IR thermometer is positioned at a certain angle with respect to the machine's main axis. Digital temperature sensors have been mounted on the rotor to measure the excitation winding surface temperature for comparison.