Safety theory contains a description of events that threaten human health, the existence of technical objects, and the natural environment, and presents principles for analyzing systems from the perspective of safety. In the literature on system safety, two basic concepts are distinguished: safety (bezpieczność) and security (bezpieczeństwo).
System safety, defined as a feature of a system that conditions its existence and functioning in a way that does not threaten the life and health of the operator and other people within the system’s range of influence, does not threaten itself, and does not threaten the existence or disrupt the proper functioning of other systems and the surrounding environment; safety is a relative property – its level depends not only on the values of the features describing the system but also on environmental influences and the operator’s control actions. System security is defined as its state. The state of system STi at time t is determined by the instantaneous values of the features xj, j=1,2,3,…,k, of the set X formed from the point of view of its safety.
Limit values of safety features
Since a system changes its states over time under the influence of forcing factors, it is necessary to establish limit values xgr and critical values xkr of the features determining its state. Safety is a feature that takes on different values depending on safety states. The paper proposes the following classification of safety states: 1 – intentional state, in which the values of the features describing the system have reached the expected values, 2 – acceptable state, in which the values of the features describing the system fall within established limits, 3 – limit state, in which at least one of the features describing the system has reached the limit value, 4 – critical state, the achievement of which means the possibility of system destruction.
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Source: Logistyka Magazine