RESEARCH OF IMPULSE OVERVOLTAGES IN HIGH VOLTAGE CABLE LINES WITH CROSS BONDING CABLE SHEATH

In the paper, a mathematical model of a power transmission cable line with cross bonding of screens is developed for the study and analysis of wave processes of overvoltage pulses during the cross bonding of screen contours. Equivalent and calculation schemes for the cross bonding of cable line shields are proposed, for which analytical expressions for calculating overvoltage maxima are obtained. Based on the analysis of the wave processes occurring in cross bonding cable shields of the three-phase system, it was established that when estimating the maximum voltage on the shields of the cable line, it is permissible not to take into account the waves reflected from the nodes located behind the node under consideration in the direction of wave travel. On the contrary, it is recommended to take into account the mutual influence of the phases, if we approximately accept the wave resistance of the screen-earth channel, which is equal to the wave resistance of the inter-screen channel. It has been established that taking into account the mutual influence of the phases leads to a decrease in the amplitude of the pulse and a reduction in the time of its influence, therefore, in order to calculate the overvoltage maxima, it is necessary to take into account the mutual influence between the screen-screen channels of neighboring phases.