345-kV Switching Surge Tests Exploring Dynamic Voltage and Arrester Performance

This paper presents the results of switching surge tests on a 119-mile 345-kV circuit. For various methods of terminal switching, probability analysis is made of the magnitude and frequency of occurrence of transient and dynamic voltages when energizing the circuit through an autotransformer from systems with different soure impedances. Test results are compared with results of a model study on the same circuit. The good performance of current-limiting gap arresters is demonstrated in oscillographs showing arrester sparkover levels, discharge currents, reseal times, and reignition phenomena. The duration of dynamic voltages and the exposure of arresters to dynamic voltages above arrester rating are demonstrated. Data are presented on the transient performance and arcing period of 345-kV double-break disconnects when switching magnetizing currents of 200- and 400-MVA autotransformers.