Dependability factors of microprocessor protection software

Aim. An analysis of the distinctive features of the functional dependability of software that are common to critical real-time applications in respect to microprocessor protections. Dependability indicators are among the primary operational characteristics of relay protection. As such protections migrate to microprocessor technology, it became necessary to characterise their operation and dependability with software dependability along the hardware dependability. The importance of the tasks it solves in the process of operation puts it into the category of programs used in critical real-time applications. That, in turn, toughens the requirements for their dependability evaluation.Methods. The comparative analysis allowed evaluating the unity of the examined operational dependability factors of the software as part the examined applications, while identifying certain distinctive features that are common to relay protections that use microprocessors.Results. The paper provides an example of such estimation that shows that, given all the complexity of testing microprocessor protection programs, the contribution of software errors still is 2,5% from the overall contribution.Conclusion. It is shown that microprocessor protection programs fall into the category of critical real-time application programs, which allows using the experience and characteristics of such software as part of relay protection. Nevertheless, the paper cites certain distinctive features that are common only to microprocessor-based relay protection. Further tasks are specified.