We are having an issue with our GE 7FA EX2000 exciter tripping at base load. The unit will operate fine below base. Within 15 minutes of going into base load, the unit trips, and we are receiving fault code 495. We have tested the PT's and fuses feeding the exciter circuits with no findings. We have also changed the PTCT and TCCB cards in the EX2000 with no avail. Has anyone experienced this, or have any suggestions on where we could look next? GE is on site and has not come to a solution yet.
Thank you in advance!