Method for Cable Lines Insulation Monitoring

The article deals with the possibilities of using a device that reacts to reverse and zero-sequence currents to monitor the insulation of cable lines. The main problems that inevitably arise during the diagnostics of cable lines by the equipment designed for working with disconnected lines are indicated. The disadvantages of the devices used to control the insulation of cable lines reacting to zero-sequence currents because of the possible uncertainty in the location of the occurrence of these currents or because of unbalanced loads are presented. It is shown that the use of the placement of control devices at the beginning and end of the lines makes it possible to obtain more reliable and valid results in determining the cause of the appearance of these currents, and, consequently, the causes of the appearance of these currents. The use of reverse sequence currents is also considered to reveal the weakening of insulation between the phases of cable lines.