Our 55 MW Steam turbine is witnessing high -ve axial shift (-0.55) mm & high -ve differential exp.(-2.50) mm at full load. Set value of axial shift is 0.55 mm with design tolerance (-1.7 mm towards front of turbine & +1.2 mm towards generator) & differential expansion design limit is +3.0 to -2.5mm.
Turbine pads (thrust & surge) temperature is normal with drain oil temperature within limit. What could be cause behind such a high -ve values of axial shift & differential expansion ?? Does generator magnetic off-set play any role behind this problem, if we set this value beyond lower or upper design limit of magnetic offset ???
regards
kamnesh

Pl. check if your zero point for the proximity probe is correct.
Regards
Irshad