Capacity Calculations
Capacity represents some user-defined parameter that is used to model a multi-state system. The three states most commonly considered are operating, degraded, and failed, even though other additional states might exist. In a typical three-state system, 100% capacity indicates that the system is fully functional, 75% capacity indicates that is partially functional, and <75% capacity indicates that it is considered failed.
Capacity is often used to measure either some sort of flow (of water or chemicals) or the data transfer of electrical current. The following table describes flow and electrical networks.
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Type
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Description
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Flow Network
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When selected, capacity is split evenly among all active outputs at a junction. For example, a junction with an input capacity of 100% and two outputs has a capacity of 50% on each output. An example is given in Flow Network Example.
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Electrical Network
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When selected (default) capacity propagates evenly for all active outputs at a junction. Unlike in a flow network, capacity does not get split. You get the same amount of power available at all output branches. For example, a junction with an input capacity of 100% and two outputs has a capacity of 100% on each output.
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In some cases, if all blocks in the system have a capacity of 100, then capacity equals availability * 100. However, if availability is analytically calculated, this is not the case because capacity is always simulated. If a flow network has redundancy, then this might not be the case because the system can be failed but still have a nonzero capacity.
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Avoid capacity considerations when a system has blocks with load-sharing redundancy. For a block with load-sharing redundancy, capacity does not make must sense. Indirectly, capacity is already considered in the load-sharing mechanism. For more information, see Capacity.
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