Effect of Overhead Ground Wire Installing under Distribution Lines on Surge Arrester Failures

Distribution surge arresters are often damaged by lightning strokes, in particular, winter lightning. An overhead ground wire (OGW) is one of effective measures against surge arrester failures. However, adding the conventional OGW to existing overhead power distribution lines needs the power interruption for construction as well as high costs because of installing them above phase conductors. Experimental results show that a covered conductor for distribution lines is more difficult to attract lightning than a bare conductor. Moreover, lightning strokes to distribution pole heads occupied over 90% of all lightning strokes in the observation result of lightning strokes to actual distribution lines without the conventional OGW, and lightning strokes to power lines were hardly observed. These results indicate that the pole heads shield the power lines from direct lightning strokes. Therefore the author studies the application of an OGW under the distribution lines (UGW) for reducing surge arrester failures. The lightning performance of the UGW is estimated by the Electro-Magnetic Transients Program (EMTP) and its effectiveness is demonstrated. The measure is expected to cut costs of construction and maintenance for lightning protection.