Spare model under the constraint of spare sufficiency

The model of spare quantities by using the marginal analysis method to confirm the quantities of the spare is established, which is through the spares particular parameter and spares sufficiency researching based on the availability centered analysis of spare supplying. Therefore, cost optimization can be achieved as well as the equipment spares sufficiency, and then the requirement of system availability is satisfied. Finally, the further demonstration and verification of the spare model are given through the particular case applying.