PURPOSE: To secure the safe operation of a steam turbine by providing the circuit to switch plural steps of warning set value successively.

CONSTITUTION: A function generator 20 is added after the conventional eccentric module 5. Accordingly it is made possible to monitor the eccentricity from the turning operation upto near the medium speed of the number of turbine turnings successively with the eccentricity of the steam turbine operating by partitioning the operation zone with a warning zone by the three operation patterns at turning time, turbine revolutions rise starting time and the number of revolutions rising time by each conditional contact of a turning start 21, the valve opening 22 by ventilation, the rise in turbine revolutions, etc.