Flexible Conductor with a Mechanical Device for Short-Circuit Overloading Prevention

The short-circuit current in high voltage transmission electric lines is considered as a serious risk for the electrical systems. This is a transient overload of the electrical system characterized by a sudden and violent rise, for a short period of time. The expected short-circuit current magnitude is one of the most important parameter in the design process of the electrical system components, such the support structures in the transformer substations. The occurrence of short-circuit current induces significant transient electromagnetic forces in the conductor and lead to its substantial deflection. The proposition of the present work is to add a Force Safety Device (FSD) to the flexible buses which will restrict the transmission of the unwanted forces to the substation portals. The FSD is a metallic cramp composed with two weakened cross section areas in its arms, which are calibrated to plastic deformation. The device operates similar to a safety fuse of any electrical device, while being replaced when tripped. Because of construction simplicity, the FSD is much cheaper than the strengthening of substation portals and can be economically sound. The paper deals with the investigation of FSD effectiveness. A mechanical finite element model, including various components, such bus conductor, insulators, FSD, portals masses and portals stiffness, is built. The ANSYS transient analyses with different parameters are carried out. Practical situations were simulated and the results showing the effectiveness of the FSD are presented.

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