While the decarbonization of power sources is progressing, thermal power generation facilities, which are positioned as an important source of power supply also in the future because of their flexibility in output adjustment, must be made more efficient to reduce CO2 emissions. In a steam turbine, which is a key component of a thermal power generation facility, appropriate management of the small clearance between the rotating and stationary parts in the steam turbine casing enables efficient conversion of steam flow into rotational energy, leading to the improvement in power generation efficiency. Therefore, we developed an eddy current gap sensor to manage the small clearance in the casing of a steam turbine during operation, and confirmed that the sensor can measure small clearances of 0 to 3.5 mm within ±120 μm of measurement accuracy for more than 1,000 hours.
