Influence of flexible conductors on the seismic responses of interconnected electrical equipment

A model of interconnected electrical equipment was established to study how flexible conductors affect the seismic responses of electrical equipment. The model was validated by conducting shaking table tests on an interconnected 220-kV full-size disconnecting switch-breaker system. The system was connected by flexible conductors of varying slackness, Afterwards, the model was adopted to carry out parametric analyses of the interconnected equipment. The tests and analyses showed that the critical sag-to-span ratio of a flexible conductor is related to equipment frequency and peak ground acceleration. Specifically, when the sag-to-span ratio of the conductor was less than the critical ratio, the horizontal terminal force increased rapidly. Even if the conductor was not straightened in the earthquakes considered, its vibration amplified the seismic responses of the interconnected equipment. Both the frequency ratio of the interconnected equipment and the frequency of the softer equipment influenced the interconnected effects of the electrical equipment. Furthermore, the displacement of the lower-frequency equipment made a larger contribution to the observed coupling effects.