Volt-time Flashover Characteristics and Lightning Performance of a Compact EHV Transmission Line with Composite Insulated Cross-arms

Compact lines offer various technical advantages and can support energy transition in a resource conscious and environmentally friendly manner. This paper presents the Volt-time flashover tests and electromagnetic transient simulations performed to optimize the insulation design of a compact 345 kV transmission line with rotatable (pivoting type) composite insulated cross-arms. Two design variants of the insulated cross-arm were tested. The obtained Volt-time curves indicated that the design of the high voltage yoke of the insulated cross-arms has minimal influence on the lightning flashover characteristics. These curves also exhibited a close alignment with the curve predicted using the CIGRE leader progression model. Best-fit leader progression model constants were derived for the insulated cross-arms from their tested Volt-time curve and implemented in PSCAD. The critical flashover currents were estimated and the backflashover performance of the compact line was found be significantly improved in comparison to an equivalent non-compact traditional design.