| 摘要 |
PURPOSE:To enable accurate detection of cracking on a steam valve by extracting a specific signal among acoustic signals detected from a steam valve in a steam tubine. CONSTITUTION:Acoustic emission associated with the development of deformations or crackings in the perimeter of a branch tube 2 is detected with an AE element 3 mounted to the branch tube section 2 of a steam valve 1 and is converted into an electrical signal. After amplification 4 of the signal, noise is removed with a filter 5. After the amplification 6 thereof, it is separated 7 into various frequencies and the peak value of the AE signal thus separated is identified 8. Signals with an energy level of above 2V<2>sec alone are discriminated 9 in the band range 50kHz-300Hz and an alarm 10 is actuated by the discrimination output. |
