| 摘要 |
PURPOSE:To detect abnormality of a commutator such as film abrasion and local abrasion easily with high precision during operation by detecting the vibration state of a DC machine by an acoustic sensor and analyzig a segment ripple and/or pole ripple. CONSTITUTION:The acoustic sensor 1 detects the vibration noise of the brush of the DC machine, a constant setter 4 sets the constant of a band-pass filter 3 corresponding to the segment ripple or pole ripple, and the band-pass filter 3 extracts a signal of the frequency band of the segment ripple or pole ripple component of the DC machine to be measured from the output of an amplifier 2. An autocorrelation arithmetic and addition circuit 5 varies the function Rxx(tau) of a time difference tau and the tau to find plural maximum values Rxx(taui) of an autocorrelation function, and calculates their sum value so as to grasp feature of time variation of the output signal x(t) of the filter 3. Then, it is decided from a level indicated on a display device whether there is abnormality or not. |
