PFH-calculation for complex safety functions by means of generated Markov models

Markov models are essential for modeling systems in safety and reliability calculations. Unfortunately, these models become exponentially more complex with an increasing number of components. This makes manual modeling time-consuming, complicated, and prone to error. This paper introduces a method to systematically and automatically generate Markov models. The system model is made up of components models. Then, we identify the dangerous and the productive system states. Next, we model the interdependencies of the components, as well as operating and repair strategies, and common cause failures. To counter the exponential increase in states, we simplify the model. By solving the differential equations of the simplified model, we calculate the probability of dangerous failure per hour (PFH) and availability characteristics. The simplified Markov model can be used to optimize system configurations for safety and reliability.