JPH0445672B

PURPOSE:To correctly decide the inspection timing and improve the rate of operation, by providing a plurality of contactless displacement sensors in a position oppositely facing to the peripheral surface of a water turbine runner further on its equal radial line in the axial line direction. CONSTITUTION:An upper and a bottom cover part 2, 3 provides a displacement sensor 4 in a position opposed to the peripheral surface of a water turbine runner 1. This displacement sensor 4 consists of a contactless type displacement sensor. This displacement sensor 4, being provided in each seal part A-D, is provided in plural quantity with a distance spaced in the peripheral direction of a turbine. Further, each displacement sensor 4 is positioned on an equal radial line to the displacement sensor 4 similarly provided in the other seal part. And abnormality of the water turbine runner 1 is detected by comparing an output signal of each sensor 4.