I am dealing with a 1,000KVA transformer (Delta-Delta) 13.8kV to 575Volt system and all phase to phase voltages read around 580 but the Phase to ground on the "A" Phase reads 470 to 480 volts while "B" and "C" phase are right where they should be around 300 volts. Never seen anything like this!! Any Ideas? We have checked the voltage with a multimeter under load and no load conditions and get the same results.