December 2011, Volume 2, Issue 11 BENTLY NEVADA SYSTEM 1® TIPS & TRICKSDear System 1 User,In the December issue of System 1® Tips and Tricks we’ll show you how to use Sample Filtering in System 1. This issue is basedon a recent customer request. This customer uses both our obsolete Data Manager 2000 and System 1. the old Data Manager2000 has trend plot capability which can show the Maximum-Minimum and Average values. I put together this tutorial on theSystem 1 plot sample filtering to mimic this same capability in System1.We hope you enjoy this issue.Sincerely,Your North America FAE teamThis month’s tip by: Stuart Rochon, Field Application Engineer, Chester, SCVersions: User Level:All Power User Diagnostic UserApplies to: IT GroupSystem 1 Plots Mid Level User Occasional User New User How to do sample filtering in System 11 In this article, we assume you already know how to generate various plots in System 1. I used artificial, wildly varying data to amplify the effects of filtering. This way it will be obvious how filtering affects the data shown in the plots. First I selected a point that is randomly spiking, and trended that point. I have selected a time frame that has more than the 500 data points allowed in one plot. This is indicated by the “Sample Filtering” icon in the upper left corner. The default sample filter is “Every Nth Sample”, this means that it takes the number of samples in the time frame and divides it by 500 to get “N”. Example: There are 2300 points in my plot time frame. So to get the “N” we divide 2300/500 to get a “N” of 4.6, this would be rounded to 5. In this case, the plot will show every 5th sample.
2 To see what sample filtering we are using we click on “Plots” and choose “Default Data Range” from the dropdown list.3 Choose the second tab from the left, “Plot Sample Filtering”. You can see “Every Nth Sample” is selected.4 Under filter type, click the drop-down arrow to show the “Maximum” and “Minimum” options.
5 When you select 3 15 “Maximum” (or “Minimum”) 4 9 14 1 7 8 11 13 2 10 the same process of filtering 5 6 12 the data takes place (in our case every 5th sample), but it takes it one step further and looks for the highest (or lowest) value in the group of samples. Let’s think of it as buckets of 5 samples with different amplitudes (the red lines). If we stick with the Maximum: 3, 9, 15 etc. example of 2300 samples Minimum: 5, 6, 12 etc. and every 5th sample we Every Nth: 5, 10, 15 etc. would get the samples shown to the right:6 So, let’s look at the trends: Every Nth sample (in our case every 5th)7 Maximum8 Minimum9 Of course, these are In summary: You may not always see where an alarm may have been extreme examples to show violated in a long term trend when every Nth sample is selected. But the difference in plots. looking at a shorter time frame around the alarm, suddenly you see the trend cross the limit. This is due to the Nth sample filtering method. With a 3 month trend you may have 10,000 to 20,000 samples filtered to every 20th to 40th point. If the alarm was shorter than that number of points, it may not show up on the trend. So, creating plots with Maximum and Minimum settings as well can be a very valuable tool.
DID YOU KNOW?Bently Nevada now offers an on-line Motor Stator Insulation Monitor (MSIM), which is incorporated in our 3500 seriesmonitoring system and consequently can be interfaced to System 1 and/or DCS for trending and diagnostics. TheMSIM solution delivers the industry’s only continuous, direct measurement of stator winding capacitive and resistiveleakage currents, offering a credible indication of motor availability and reliability. The system enables operations andreliability personnel to make effective and knowledgeable process rate decisions without damaging the motor. For afact sheet, please click on this link: http://www.ge-mcs.com/download/appsolutions/GEA19847_MSIM_Factsheet_r3.pdf . For more information, please contact your local Sales Manager or FieldApplication Engineer.Bently Nevada Technical Support:firstname.lastname@example.orgBently Nevada website:http://www.ge-mcs.com/en/bently-nevada.htmlSystem 1 Blog (You’ll need to join the forum):http://supportcentral.ge.com/blog/blogs_frame.asp?prod_id=20858