Achmad Syahrudin Fakhri. Abstract. Generators as the main source of continuous electricity supply to various places. To maintain generator performance and stability, a strategy is needed to maintain the generator. The strategy for generator maintenance can be routine maintenance and predictive maintenance. Predictive maintenance is maintenance that is based on data indicating warnings called potential failure. The results of predictive maintenance will be taken into consideration in carrying out subsequent maintenance. By carrying out predictive maintenance, it is hoped that it will prevent system failures that can interfere with generator operation so that the electricity supply can be fulfilled. To implement this, the authors use data from the Mendalan hydropower plant in Malang district. The data used in this study are data from 2018 to 2019. The data of this study include data on generator insulation resistance, bearing vibration (vibration) at the generator point and stator coil temperature (stator winding temperature). The method used to analyze data using the Markov method. The Markov method is a mathematical method to estimate the properties of a variable in the future based on the characteristics of these variables in the past .