345kv/138kv wye connected autotransformer with 34kv delta tertiary.
34kv tertiary has 3 wye connected 300/1 pt's and 2 34kv/240-120v open delta station service transformers.
Transformer was energized for the first time from the 345kv gcb with open 138kv breaker.
Approx 10 sec later, xfmr tripped...