A cheaper control option is the use of systems for periodic monitoring of the condition of cable lines, in which parameters are also measured on a working line in the “on-line” mode, but not continuously, but at certain time intervals. Therefore, such monitoring is called periodic. When conducting periodic monitoring, the condition must be met that the time interval between measurements should be at least two to three times less than the standard time for the development of a defect, from the moment it occurs to reaching a critical level. Only in this case is the possibility of skipping rapidly developing dangerous defects reduced to a minimum.