The purpose of this article is to introduce to the methodology of increasing electromagnetic compatibility in distributed system, on the example of the implementation of works in the field: "Research and improvement of electromagnetic compatibility of railway traffic control devices and rolling stock", which are the subject of the BRIK project. The methodology is defined here as a set of rules for conducting research in order to achieve an intended goal. The article proposes a procedure to improve the EMC condition of distributed systems. For monitoring the quality of the system operation in terms of electromagnetic compatibility, the implementation of the OEE indicator was suggested.