In this section, semi-Markov models of some one-component systems with regard to latent failures control are built. Stationary reliability and efficiency characteristics are obtained. The models of systems with and without component deactivation while control execution are given in Sections 2.1 and 2.2, respectively. In Section 2.3, approximation of stationary characteristics of the system without deactivation is carried out. The system model with component deactivation and possibility of control failure is built in Section 2.4. Section 2.5 covers the system model with component deactivation and preventive restoration.