Abstract: The classification of online insulation monitoring for generator was introduced. The composition, the working principle and the output trajectories under various overheating conditions of 390H generator condition monitor system were discoursed. The best advantage of the generator condition monitor system is that it can online monitor the overheating inside the generator body and can early forecast the generator fault. But also the generator condition monitor system has some defects such as the poor interpretation capacity, certain false alarm rate and etc.

Key words: generator condition monitor system, insulation monitoring, classification, output trajectory