Measurement-computing Medallion Rotate rev.2.3 Instrukcja Użytkownika Pobierz pdf (Strona 26)

Medallion Rotate Manual October 2000

APPLICATIONS

The Medallion Rotate Waterfall plot is ideal for non-steady state processes

such as variable speed machinery. The plot shows you the change in the

appearance of the spectra over time. This is particularly useful in the following

applications:

• Analyzing the machine’s behavior during run-up or coast-down.

• Diagnosing amplitude modulation (“beat”).

• Determining the frequency and severity of resonances, such as shaft

critical speeds.

• Analyzing a machine’s response to speed or load variations.

• Isolating non-varying spectral peaks (such as those caused by electric

power or resonance) from speed-dependent peaks (such as vibration).

• Isolating spectral peaks from other processes that are linked to the

machine.

• Ruling out spurious spectral peaks caused by aliasing when using time-

capture equipment that does not have anti-aliasing filtering. See

“Aliasing.”

• Performing Waterfall analysis directly on a DC speed signal to diagnose

torsional problems. For more on torsional analysis, see “Torsional

Analysis.”

INPUT SIGNAL REQUIREMENTS

Medallion Rotate Waterfall analysis

requires a smoothed speed curve from

performing a Tachometer analysis if you

want to use the order tracking features of

the Waterfall plot. When collecting the

non-tachometer data (vibration,

temperature, …), note the following:

• If you want to see low frequency

data in the Waterfall analysis, make sure that the high pass filter setting

in your analyzer is not excluding the desired low frequencies.

• The sample rate in the analyzer must be at least 2.5 times the maximum

frequency of interest to avoid aliasing.

• The choice of window function for

analysis depends on the type of

resolution you need (amplitude or

frequency resolution).

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Measurement-computing Medallion Rotate rev.2.3 Instrukcja Użytkownika Strona 26