Turbine differntial Expansion

When the turbine is in cold condition and de-coupled fix the probes at both ends on the radial faces of the collars and adjust to zero reading on both the probes as indicated on the panel. If axial probes are already available on either side these may be used. After starting the turbine and heating up the readings on either will indicate + or -. If both are minus the readings need to be added up to get the differential expansion. If one is + and other minus, delete the plus from minus to get the diffe. expansion.