Abstract
Ultra high voltage transmission lines must be protected from lightning surges and the following large-current fault arcs. Horns which are installed at the jumpers on the strain towers have a role to protect the insulators from the fault arcs by coordinating insulation strength and holding large-current fault arcs between the horns. Although a flat surface of the electrode tip with a small diameter effectively meets these requirements, it results in the deterioration of corona discharge depressing capabilities in a steady state on power transmission lines. In order to improve corona discharge depressing capabilities and to reduce deflection of arc jets, we finally developed two types of hemispherical shaped arc horn electrodes with slits. The arc jet control performance of those horns was experimentally disclosed as follows:
(1) Two types of arc horn electrodes with four or six slits show remarkable are jet control performance in the current of larger than 5 kA.
(2) The addition of a rod type central electrode at the center of the hemispherical shaped electrodes results in the considerable extension of arc jet controllability in the wider current zone by containing the arc spot within the tip area of the central electrodes.
Based on the above results, arc horn electrodes with slits have been designed and utilized for practical application.
