MEASURING INSTRUMENT FOR WHEEL CHAMBER-SHAFT EXPANSION DIFFERENCE OF STEAM TURBINE

摘要

PURPOSE:To enable measuring by switching to the sensor of a normal part at the trouble time of one part of sensor by optionally switching the detected output of two sensors and the respective independent detection output of two sensors. CONSTITUTION:The output signal of a differential amplifier circuit 7 is taken out as the output signal 9 of a wheel chamber - shaft expansion difference measuring circuit 8 because a 2nd selective switch 13 is selected so that contacts 1C and 1B may be closed in a normal state. If a probe sensor 3 or preamplifier 5 be troubled, for instance, in this state, the 2nd selective switch 13 is selected so that the contacts 1C and 1A may be closed and a 1st selective switch 12 is selected so that contacts 2C and 2A may be closed. The output signal of a 2nd signal converting circuit 11 of the probe sensor 4 side, which is normal thus becomes the output signal 9 of the wheel chamber - shaft expansion difference measuring circuit 8.