| 摘要 |
PURPOSE:To detect abnormality of a commutator such as film breakage and local abrasion easily with high precision during operation by detecting vibrations of a DC machine and analyzing a segment ripple and/or pole ripple. CONSTITUTION:A vibration sensor 1 detects vibrations of the brush of the DC machine from the brush or a brush holder, etc., a constant setting circuit 4 sets the constant of a band-pass filter 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 so as to grasp features 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 6 whether there is abnormality or not. |
