Microprocessor relay protection devices (MP RPD) are an integral part of the automated control system (SCADA) of the electrical part of energy networks and systems, because they provide a high degree of informatization of electric power processes. MP RPD are intelligent systems with the ability to be improved by changing software and using more advanced principles and algorithms for the protection. Such algorithms are signal filtering algorithms that are difficult to implement due to the large volume of operations for processing the input signal.  An effective algorithm for extracting symmetrical components for MP RPD was developed. The filtration of symmetrical components is based on well-known relationships, which are generally presented as follows.