The electric power industry digital transformation features and the intelligent electronic devices (IEDs) introduction in the low-voltage circuits of power stations and substations are considered. The analysis of normative documents and standards is carried out. The features of scheduled maintenance of relay protection and automation devices are determined, the possibilities and prospects of organizing condition-based maintenance are considered. The mandatory steps required for any type of

more »

... enance are defined. A method for checking the electrical and time characteristics of the overcurrent protection of an intelligent electronic device is proposed. The device is designed in accordance with the IEC-61850 standard and operates in the local area network of a digital substation of architecture III