Study on the influence of insulator on the coupling effect of transmission tower-line system

Abstract

There is a coupling between transmission tower and lines. Traditionally, it is assumed that an insulator is in a tight connection with tower. In fact, both tight and loose connections exist. This paper studies the influence of connection state on system dynamics. The tower-line system rigged with the adjustable connection state of insulator was built. We used modal test method to study the coupling effect. The influence of the line is mainly in the longitudinal and torsional mode. It has less influence on the lateral mode. The damping increases for tower-line system and is the largest for loose connection state. The loose connected system’s first three modal frequencies are almost the same as that of the tower. However, the tight connected system’s longitudinal and torsional frequency decreases. The difference caused by connection state of insulator should be considered. Modelling method under different connection state should be different. The traditional finite element method can be used for tight connection. Under loose connection state, the insulator-line system can be regarded as a tuned mass damper attached to the tower.