The article analyzed and identified the main sources of interference, disrupting the work and reliability indicators of the system, which can lead to malfunction of system of microprocessor relay protection and automation for electric stations and substations, as well as elements and actuators of open distribution devices. According to official data, modern microprocessor-based relay automation systems operate with a reliability coefficient that is not lower than 0.998. Further increase in reliability requires the development of technical measures, namely, requires the use of power and signal cables that must meet the requirements for specific parameters of inductance, capacitance and active resistance, and also requires the use of special placement of cross sections of conductors inside the cable. Secondly, it is shown that to increase the reliability of information transmission it is necessary to switch to serial communication channels, but the amount of information per channel should be strictly limited. The estimation of economic indicators of the system and its dependence on the reliability of the system is given. Thus, with an increase in reliability by 1.5-2 times, it is necessary to increase the cost of design and commissioning of such a system by about 2 times. It is recommended to use in addition to the regulated maintenance procedures a mandatory assessment of the level of interference in the system in order to maintain a stable and reliable operation of the relay automation system. Experimental and calculated data confirmed that the most difficult situation to ensure the reliability of the system is associated with thunderstorms and lightning. This circumstance dictates the necessity of evaluation and measuring the parameters of a common system of earthing. The methods of evaluation and diagnosis of faulty components of the system are proposed.
