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Line Noise, RMS, and Ski Slope Data Validation Checks in NI InsightCM 3.3

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Line Noise, RMS, and Ski Slope Data Validation Checks in NI InsightCM 3.3

Questions about the following:  

Line Noise Ski Slope and RMS checks.PNG

The Line Noise check suggest a "suspect value" in the Line Frequency spectral band.  What is the "suspect value" and how is this determined.  We are getting a lot of line noise, yet do not see a strong peak in the spectrum.  

 

The Low Signal wording is confusing.  It "Checks the signal for Low RMS levels".  Does this mean it is looking for RMS values across the waveform that are less than 0.1 RMS, and that to pass the check it has to be higher than 0.1 RMS?  

 

The Ski Slope calls for a "suspect amount" of low frequency energy.  Can you define low frequency and suspect amount?

 

Thank you.  

 

Preston

Preston Johnson
Principal, Intelligent Monitoring and IIoT
Allied Reliability Group
512 431 2371
johnsonp@alliedreliability.com
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Accepted by topic author preston_johnson
01-16-2019 01:58 PM

Re: Line Noise, RMS, and Ski Slope Data Validation Checks in NI InsightCM 3.3

Preston - 

Line noise checks to see if the peak at line frequency is the largest peak in the spectrum.  Note that if running speed is also near line frequency, this rule will not be run (because we don't know if the peak is 1x or line noise)

 

Low Signal - Does this mean it is looking for RMS values across the waveform that are less than 0.1 RMS, and that to pass the check it has to be higher than 0.1 RMS?  Yes.

 

Ski slope - This fails if the spectrum 'looks' like a ski slope.  The first value must be the highest in the spectrum, and the next two must be decreasing in value.

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