Abstract: The turbine rotor expansion of GE S109FA class singleshaft gas turbine unit was measured by dual sensor. In the MK VI control system, the rotor expansion measurement and calculation module was protected by three stages password, and this level password was not provided to users. This makes great troubles for thermal technician in maintenance of rotor expansion measurement system. By using collected various technical materials of rotor expansion measurement, combining with field installation and maintenance experiences, the working principle of the calculating module was extrapolated. The result can be used as reference for thermal technicians in installation, debug and location of rotor expansion measurement system of same type equipment.

Key words: gas turbine, rotor expansion, correction factor, location