BACKGROUNDMaterials management is one of the main elements of managing all types of businesses. Material management plays an important role in supporting business performance, in terms of customer satisfaction, production cost and financial performance. Ruauw (2011) stated that the necessary raw materials should be available in sufficient quantity to ensure smooth production. However, the amount of inventory should not be too large so that capital is tied up in inventory and costs. Meanwhile, the inventory is neither too large nor too small as it can slow down the production process. Failure to control material inventory will result in failure to obtain profits. It is important for every company with inventory control to obtain the optimal inventory levels in order to maintain a balance between the cost of inventory being too high and the cost of inventory being too low. PT Pembangkitan Jawa Bali (PJB) is one of the state-owned enterprises that manages some power. factories in Indonesia. PJB has different types and characteristics of power plants scattered across Java and Bali. PJB is responsible for managing power plants in the Java and Bali island region with certain key performance indicators. In the operational management of a power plant, there are two key performance indicators. Initially, the availability of power plants to produce electricity and the reliability of power plants. The first key performance indicator was the availability of power plants to produce electricity. This availability number is called the Equivalent Availability Factor (EAF). Then, the reliability of the power plant is formulated as equivalent force failure rate (EFOR). This EFOR number reflects the long duration of unplanned outage of...... middle of document ....... Inventory monitoring and measurement methods. Logistics information management. Flight. 9, no. 3, p. 11. Ruauw, Eyverson., (2011). Pengendalian Persediaan Bahan Baku (Contoh Pengendalian pada usaha Grenda Bakery Lianli, Manado). Association for Science Education. Flight. 7, no. 1, pp. 1-11. Jamshidi, H. and Jain, A. (2008). Multi-criteria ABC inventory classification: with exponential smoothing weight. Journal Global Trade Issues. Flight. 2, no. 1, pp. 61-67. Teunter, Ruud H, Babai, M Zeid and Syntetos, Aris A. (2010). ABC classification: service levels and inventory costs. Production and operations management. Flight. 19, no. 3, pp. 343-352. Abuhilal, Laith, Gaith, Rabadi, Sousa-Poza, Andres (2006). Supply Chain Inventory Control: A Comparison Between JIT, MRP, and MRP with Information Sharing Using Simulation. Journal of Engineering Management. Flight. 18, no. 2, p.. 51-57