Field Measurement or Switching Surges as Modified by Unloaded 345-Kv Transformers

This paper presents results and analyses of extensive field tests to determine how unloaded transformers affect switching surge waveform and magnitude when energizing and de-energizing intermediate-length lines. Particular emphasis is placed on transformer-terminated lines. Switching of transformer-tapped lines and low-side switching of combined autotransformer and connecting high-side line are discussed, and the results include data from tests on both 345-kv and 138-kv systems.