A Computational and Experimental Method for Determining the Current in the Braid of a Control Cable During a Short Circuit

Non-equipotentiality in a grounding device can cause thermal heating in the screens of control cables that are grounded on both sides of high-voltage substations. At the same time, there is currently no approach for assessing the thermal endurance of cable screens that takes into account the configuration of the grounding device, the properties of the ground, and the connection. This paper presents a methodology for the experimental and computational determination of the thermal endurance of control cable shields in secondary circuits of 220–500 kV substations under short-circuit (SC) conditions. The method is based on full-scale imitation experiments using a sinusoidal current generator and verified numerical modeling in the ORU-M software. The potential and current density distribution in the cable shields were determined. The results showed that current densities in some circuits exceed permissible levels, confirming the risk of thermal damage. It was found that reconfiguring the grounding system—by densifying ground electrodes and increasing connections between grounding points—can reduce current density to acceptable values. The presented method allows for reliable assessment of the thermal endurance of cable shields without decommissioning the substation, making it suitable for the design and modernization of high-voltage facilities.