The use of Markov chain method to determine spare transformer number with 3-criteria parameters

System failure cannot be avoided, one of the solutions to maintain system reliability is with the existence of spare equipment, and however the number of spare equipment will increase the investment costs. Currently, spare transformer calculation study only considers one criteria in state transition model, a new model which considers other criteria such as transformer condition and transformer loading is needed. Java Bali 500/150 kV Transformer case study was used in order to show the usefulness of the proposed model.