The use of CAD systems for investigation of electronic circuits reliability and safety and their application in education

Electronic control systems are widely used in controlling safety-critical equipment and security techniques. Almost all electronic circuits and system was damaged in the course of time. The operation of the system or equipment is often interrupted or disturbed by the influence of failure. A fault can even be hazardous if it occurs in a safety device, accidents preventive shielding or a control system. In order to make the electronic equipment safe already in designing, there must be a possibility to estimate the reliability and safety of the device. The railway control devices must be not only working but so they must be a fail-safe. Important role in these requirements has the computer modeling and computer analysis of reliability and safety behavior of such systems. The aim of this paper is to demonstrate some examples, worked out by "RAMS software tools". These examples are electronic circuits that are used in the equipment in the Bulgarian Railways. The reliability and safety analysis of the schemes is performed.