Database Setup: An Example Of An Effective Database Setup

The exact nature of your database setup and the specifics must be addressed according to the vendor you purchased your software from. Most programs fail because usable, worthwhile data can not be extracted from the database. Why does this happen ? The software usually has certain useful features such as reporting capabilities that can be accessed - if the database is created in such a way as to not only take advantage but to make the best use of those features.

By way of a single example - and their are numerous ways to set up a database - the service company Vibe-Assist looked at two ingredients that went into the collection and analysis of data - what information they wanted vs. what the reporting capability of the software was (Entek's Odyssey™) - and came up with database setup templates that are used for creating an effective database structure that uses software features of Odyssey to provide information we want. By generating a database structure that takes maximum advantage of a powerful software reporting feature, Vibe-Assist reduced their analysis time by an incredible 80% or so. This new database structure did not generate this huge improvement by reducing machinery protection or analysis accuracy. On the contrary, the new setup improved the reliability of the analysis and improved the level of protection possessed by the machines they monitor. In order to illustrate the value of an effective database setup, Vibe-Assist has agreed to share a few of their component setups along with an explanation of the logic behind the database structure. Shown below are examples of a direct drive, 4-bearing machine and a belt-drive, 4-bearing machine. The links below under the "Type" of reading will take you to explanation pages for each of the readings. Direct Drives Belt Drives Explanation of Readings Sample Report

Direct Drive
Bearing 1
Reading	Type	Max Freq	# of Lines	Units	Direction
1	Trend & Spectrum	30kcpm	800	velocity	horiz
2	Trend & Spectrum	120kcpm - or - 60kcpm*	800	acceleration	horiz
3	Spectrum Only	20x rpm up to 60kcpm	800	envelope	horiz
4	Time Domain	5-9 revolutions or  relevant period	2048 bytes	acceleration or velocity	horiz
5	Trend & Spectrum	240x rpm	800	acceleration	horiz

* - For the acceleration spectrum, use 120kcpm for machine speeds over 1200 rpm and 60kcpm below that.
 

Direct Drive
Bearing 2
Reading	Type	Max Freq	# of Lines	Units	Direction
1	Trend & Spectrum	12kcpm	1600	velocity	horiz
2	Trend & Spectrum	120kcpm - or - 60kcpm*	800	acceleration	horiz
3	Spectrum Only	20x rpm up to 60kcpm	800	envelope	horiz
4	Time Domain	5-9 revolutions or  relevant period	2048 bytes	acceleration or velocity	horiz

* - For the acceleration spectrum, use 120kcpm for machine speeds over 1200 rpm and 60kcpm below that.
 

Direct Drive
Bearings 3 & 4
Reading	Type	Max Freq	# of Lines	Units	Direction
1	Trend & Spectrum	30kcpm	800	velocity	horiz
2	Trend & Spectrum	120kcpm - or - 60kcpm*	800	acceleration	horiz
3	Spectrum Only	20x rpm up to 60kcpm	800	envelope	horiz
4	Time Domain	5-9 revolutions or  relevant period	2048 bytes	acceleration or velocity	horiz

* - For the acceleration spectrum, use 120kcpm for machine speeds over 1200 rpm and 60kcpm below that.

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Belt Drives
Explanation of Readings
Sample Report

Belt Drive
Bearing #1
Reading	Type	Max Freq	# of Lines	Units	Direction
1	Trend & Spectrum	12kcpm	800	velocity	horiz
2	Trend & Spectrum	120kcpm - or - 60kcpm*	800	acceleration	horiz
3	Spectrum Only	20x rpm up to 60kcpm	800	envelope	horiz
4	Time Domain	5-9 revolutions or  relevant period	2048 bytes	acceleration or velocity	horiz
5	Trend & Spectrum	240x rpm	800	acceleration	horiz

* - For the acceleration spectrum, use 120kcpm for machine speeds over 1200 rpm and 60kcpm below that.
 

Belt Drive
Bearing #2
Reading	Type	Max Freq	# of Lines	Units	Direction
1	Trend & Spectrum	12kcpm	1600	velocity	horiz
2	Trend & Spectrum	120kcpm - or - 60kcpm*	800	acceleration	horiz
3	Spectrum Only	20x rpm up to 60kcpm	800	envelope	horiz
4	Time Domain	5-9 revolutions or  relevant period	2048 bytes	acceleration or velocity	horiz

* - For the acceleration spectrum, use 120kcpm for machine speeds over 1200 rpm and 60kcpm below that.
 

Belt Drive
Bearings 3 & 4
Reading	Type	Max Freq	# of Lines	Units	Direction
1	Trend & Spectrum	6kcpm	800	velocity	horiz
2	Trend & Spectrum	120kcpm - or - 60kcpm*	800	acceleration	horiz
3	Spectrum Only	20x rpm up to 60kcpm	800	envelope	horiz
4	Time Domain	5-9 revolutions or  relevant period	2048 bytes	acceleration or velocity	horiz

* - For the acceleration spectrum, use 120kcpm for machine speeds over 1200 rpm and 60kcpm below that.

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Direct Drives
Belt Drives
Sample Report

Explanation of Readings

There are numerous other component setups in the templates - these are for generic, rolling element bearing machines running at normal speed (1000 - 3600 rpm). But this seems like an extreme amount of data - how does this help with analysis ? Well, first, each reading has a specific job to do: Reading 1: Velocity Trend - Tool that is sensitive to fluctuation (increase) in low - mid frequency ranges where mechanical problems develop (1x - 5x rpm) and, to a lesser degree, higher frequency problems such as rolling element bearings. Reading 1: Velocity Spectrum - Analysis tool for low - mid frequency problems. Higher resolution readings collected on belt drives and inboard motor bearings.  Note: By properly setting some simple statistical alarms on the trend plot, this spectrum may be turned off  because the analyst will be alerted by the overall alarm to any situation where a spectrum is required and eliminate many of these most time consuming readings. Reading 2: Acceleration Trend - Tool that is not affected by influences at 1x - 5x rpm but is increasingly sensitive to problems developing above 30kcpm such as gears, bearings and high frequency electrical. Another good candidate for statistical alarms. Reading 2: Acceleration Spectrum - Analysis tool for high frequency problem detection and analysis. Used in conjunction with the next reading . . . Reading 3: Envelope Spectrum - e.g. gSE, ESP, Peakvue, HFB and more. This plot gives information on transient impacts occurring that may be related to a bearing defect or several other sources. Reading 4: Time Domain - Can be de-activated if the analyst prefers but is an important tool to use at times. Can be set to whatever time sample the analyst chooses. Reading 5: Acceleration Spectrum - On motors only, looks for 2x and 3x rotor bar pass frequency and winding slot pass frequency - very high frequencies. So what are we left with in the best of environments ? By turning off the time consuming velocity spectrum and rely on trends only to monitor the low-frequency end of the spectrum, we are left with: Velocity overall Acceleration overall Acceleration spectrum  An enveloping spectrum  That is a total of about 5 seconds of data collection. If the velocity trends into alarm, we turn on the velocity spectrum for analysis. If an acceleration overall trends into alarm, we check the enveloping spectrum for impact frequencies and try to match up harmonics on the acceleration spectrum. This database structure protects against all possible trendable problems (as opposed to "event-based" problems that can lead to short-duration failures).

Top Direct Drives Belt Drives Explanation of Readings Sample Report The key, however, is in the simple reports that can be run. An amplitude threshold is set for the report (perhaps 0.2 in/sec or 5 mm/sec). A line is triggered for the report for every single peak that exceeds the pre-set amplitude threshold. The line on the report, shown below, includes all the location information, the Fmax, peak amplitude and frequency of the peak as well as the rpm and date. This makes initial review of the data simple and brief. This report addresses the low-mid frequency ranges that require velocity units for effective monitoring (> 30kcpm). This is the frequency range in which mechanical problems will show up: 1x - 10x rpm or so. This report does not address bearings, gears, certain electrical vibrations or any other high frequency vibration sources.

To address the high frequencies, an identical report is created to handle the acceleration spectral data. The amplitude trigger for acceleration units will typically be about 1G - a very safe, fairly low amplitude threshold. Any line on the acceleration report is investigated by first looking for any impact frequencies on the associated envelope spectrum and then by making an assessment of the vibration source. Further investigation may be necessary but the report(s) give easily accessed, easily analyzed information that prompts immediate investigation in the problem areas. Much of the data does not get looked at but that is simply because the vibration levels too low to be concerned with.