Rules for using the Acc Env Custom filter settings in @ptitude Observer

Summary

For IMx devices, rather than using the fixed and pre-configured acceleration enveloping filters (Acc Env 1 to 4), in @ptitude Observer, the user can alternatively select a frequency range and apply custom low and high frequency cutoffs to the processing. The rules that apply to and constrain these cutoff settings are described in this article.

Details

Having added an IMx, Dynamic Envelope measurement point, the user is able to select Acc Env Custom Pre-processing, rather than one of the the fixed and pre-configured acceleration enveloping filters:

The configuration of this custom enveloping 'band' is then determined by the Frequency range and the frequency limits (Between x and y [Hz]) associated with the Pre-processing, as highlighted above. 

The user should first select the desired Frequency range from the drop-down list or also select Custom there, and enter an End Freq. in Hz.

• This frequency range is the range applying to the final data, the range of a gE spectra.

Having set the frequency range, suitable values must then be entered for the custom pre-processing. These values have a mixture of absolute limits, relative limits and also limits related to the Frequency range / End Freq. setting:

• The first/lower frequency value must be set at a minimum of 5 Hz.
• The second/higher frequency value must be set at a minimum of 10x the lower, and
• The second/higher frequency value (Custom High cutoff) must also align with a green area in the matrix below: 

To use the above matrix, take the upper Frequency range or End Freq. setting and identify the 'Spectra Fmax' column that applies. Then using the Custom high cutoff columns, identify which row applies to the desired second/higher frequency value. Now check that the identified row/column intersection is green, if not, adjust the selected values to make it so.

• The far left column is indicating the rows that apply to the four pre-configured gE bands.

For example, with the Frequency range set to "0 - 200 Hz, 0 - 12 000 cpm", valid settings for the second/higher frequency value would be in the ranges 101 to 125 Hz or 626 to 12 500 Hz (but not between 126 and 625 Hz). 

Contacting SKF Technical Support Group

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