| 摘要 |
<p>The invention relates to method for analysing the condition of a machine having a slowly rotating part, comprising: rotating a rotatable part at a rotational speed (fROT) of less than 50 revolutions per minute; generating an analogue electric measurement signal (SEA) dependent on mechanical vibrations emanating from rotation of said shaft using a sensor having mechanical characteristics causing it to resonate at a certain resonance frequency (fR); sampling said analogue measurement signal at a sampling frequency (fS) so as to generate a digital measurement data sequence (SMD) in response to said received analogue measurement data; performing digital filtering (240) of the digital measurement data sequence (SMD) SO as to obtain a filtered measurement signal (SPBMD) so as to achieve a signal having a bandwidth between an upper and a lower frequency; said lower frequency (fLC) being lower than the certain resonance frequency (fR) and said upper frequency (fUC) being higher than the certain resonance frequency (fR); generating a digitally enveloped signal (SENV, SMDP) in response to the filtered measurement signal (SPBMD) by digitally rectifying said filtered measurement signal, and by digital low pass filtering of the rectified filtered measurement signal so as to generate said digitally enveloped signal (SENV, SMDP); performing a condition analysis function (Fl, F2, Fn) for analysing the condition of the machine dependent on said digitally enveloped signal (SENV, SMDP)-</p> |
