are the frogs electrically powered?
is there something else on the locomotive, other than the wheels, touch rail at this point?
with the small frog angle is the twisting of trucks making contact with frame or something in the locomotive?
if it is on the other main and coming through the crossover in the opposite direction, does the same thing happen?
if you physically turn the locomotive around on the track and run it through this crossover, does the same thing happen?
sounds like a short of some kind.