I see these around mine sites quite a bit. Many mine sites use 240 or 480 3 phase Delta ungrounded systems as permitted by 250.21 (A)(4). These transformers could also be used for a corner grounded Delta.
Few things are harder to put up with than the annoyance of a good example.
#200872 - 04/23/1108:45 PMRe: O/T pole pigs with 240/480 secondaries