What is Resonance? (Part 2)
This article is a follow on from What Is Resonance? (Part 1) and answers some of the issues not covered in that post. How do you find the resonant frequency…
Which Should I Use? Real & imaginary? Or magnitude & phase?
In one of our recent articles a question was asked regarding the practical use of real & imaginary type plots compared with modulus & phase type plots. In general, noise…
Vibration Monitoring Phase Measurement And The Tacho Signal
Any vibration signal may be analyzed into amplitude and phase as a function of frequency. The phase represents fifty percent of the information so it is most important to measure phase for vibration monitoring. Most vibrations on a rotating machine are related to the rotational speed so it is clearly important to have a measure of the speed, either directly or as a once per revolution tacho pulse. A question sometimes arises as to whether a once per revolution tacho reference signal is needed to measure phase. Is it possible to get phase if we only have a speed signal? This note gives some insight into those questions.
Actually the question that should be asked is – “Can we measure a meaningful phase, for use in vibration monitoring, if we only have a speed signal as well as the vibration signals?”
Phase Angle Between Signals
The following article was written in response to a question from a visitor to the website. The gentleman in question had been reading some of the Prosig signal processing articles and had the following question.
Dear Sir, It was interesting reading the articles in your mail.I would like to know the options available in hardware and/or software for measurement/calculation of phase angle of first harmonic of a vibration signal which is sinosoidal. The phase angle is the relative phase angle difference between the signal and the tacho - one into rpm signal. Regards. etc.
Importance of tachometer/keyphasor signal conditioning and its relationship to phase measurements
This note describes the importance and setup of a keyphasor or tachometer signal for PROTOR Remote Monitoring Data Acquisition System (RMDAS) units. RMDAS units are provided with manual tachometer conditioning…
