TC reported APS train and local fault intermittently. Staff (YIS) checked and confirmed no converterfault,. ~~~~~ 3540 TC reported APS train and local fault intermittently. Staff (YIS) checked and confirmed no converter fault.  #3540 checked and found AC1-1 shorted to ground. Isolated UVW wires and raised notification to HM for CCU change out. Notification: 2520338 Done by: Kumar / Haikel 45171