The quality factors of components are quotients made of a value in the actual state and the same value in the reference state. One can distinguish between 3 main groups: rotary components, such as turbines and pumps, in which the inner efficiency is used, heat-exchanging components like condensers and heating surfaces, in which the value k*A is used and material transporting components, in which conversion factors or separator efficiencies are used. The independence of the quality factors from the changing influencing parameters enable a continuous evaluation of the state of the plant and of the component.