BACKGROUND Materials management is one of the main components in the management of all types of companies. Materials management plays an important role in supporting company performance, which concerns customer satisfaction, production costs and financial performance. Ruauw (2011) stated that the necessary raw materials should be available in sufficient quantities to ensure smooth production. However, the amount of inventory should not be too large so that the capital gets tied up in inventory and costs. Meanwhile the inventory is neither too large nor too small because it can slow down the production process. Failure to control materials inventory will cause failure to achieve profit. It is important for every business to have inventory control to achieve optimal inventory levels to maintain a balance between the cost of too much inventory and the cost of too little inventory. PT Pembangkitan Jawa Bali (PJB) is one of the state-owned enterprises that operates some power plants in Indonesia. PJB has various types and characteristics of power plants spread across Java and Bali. PJB is responsible for operating 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 indicated is the availability of power plants to produce electricity. This availability number is called equivalent availability factor (EAF). Then, the reliability of the power plant is formulated as equivalent force outage rate (EFOR). This EFOR number reflects the long duration of the unplanned closure of... half of the document... Inventory monitoring and measurement methods. Logistics information management. vol. 9, no. 3, pp. 11.Ruauw, Eyverson., (2011). Pengendalian Persediaan Bahan Baku (Contoh Pengendalian pada usaha Grenda Bakery Lianli, Manado). Association for Science Education. vol. 7, No. 1, pp. 1-11. Jamshidi, H., & Jain, A. (2008). Multi-criteria ABC inventory classification: with exponential smoothing weight. Global Business Issues Magazine. vol. 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. vol. 19, No. 3, pp. 343-352. Abuhilal, Laith, Gaith, Rabadi, Sousa-Poza, Andres (2006). Supply chain inventory control: A comparison of JIT, MRP, and MRP with information sharing using simulation. Journal of Engineering Management. vol. 18, no. 2, pp. 51-57