Constraints and interrupts define how capacity and variability are introduced into a ReliaSim model. Together, they determine how quickly material can move through the system and how often that flow is disrupted—making them two of the most important drivers of overall performance.
Constraints represent rate-limiting operations such as machines, work centers, or processing steps. A constraint sets the maximum speed at which material can pass through a point in the model, effectively controlling throughput. In most systems, one or more constraints naturally become bottlenecks, limiting how much output can be produced regardless of upstream supply. Identifying and understanding these constraints is often a primary goal of modeling.
Interrupts introduce real-world variability by temporarily reducing or stopping flow through constrained operations. They are commonly used to represent downtime, maintenance, changeovers, or other disruptions. When a constraint is interrupted, upstream material may accumulate while downstream nodes may become starved, allowing ReliaSim to capture blocking and starvation behavior automatically as part of the simulation.
Together, constraints and interrupts allow ReliaSim to model both steady-state capacity and operational uncertainty. Constraints define what is possible under ideal conditions, while interrupts reveal how reliability and availability affect actual performance. By adjusting rates and interruption behavior, you can explore how improvements to equipment speed or reliability influence throughput, efficiency, and overall system stability.
In practice, it’s often helpful to begin by modeling constraints with simple rates and minimal interruption detail, then refine interrupt behavior as your understanding of the process improves. This approach keeps early models focused on structure while still providing a path toward more realistic performance analysis.