Engine Carbon Brushes Replacement-
Cement Mill 4
St.Dmitry
December 19, 2017
a) to build convenient for further work datasets based on the provided raw data;
b) preliminary separate exploratory data analysis of carbon brushes replacement of Cement Mill 4 engine;
c) care by outliers.
The input of the module is a csv file. The file contains an unordered dataset, with provided information of engine inspections since 2004 for each engine carbon brush. In case carbon brush was replaced due to deterioration - the event is signed by “1”, otherwise by “0”.
The outputs of the module are convenient for further work datasets based on the provided raw data.
Statistic information of maintenance periods and cases of carbon brushes replacement due to deterioration:
## Cement Mill 4 (January 2004 - February 2018)## Maintaneince days summary:## Min. 1st Qu. Median Mean 3rd Qu. Max.
## 2.00 23.00 26.00 32.35 29.00 528.00##
## Maintaneince days Outleirs:## lowerFarOut lowerOutliers upperOutliers upperFarOut
## 5 14 38 47##
## Replacement periods summary:## Min. 1st Qu. Median Mean 3rd Qu. Max.
## 12.00 33.00 58.00 96.05 108.00 782.00##
## Replacement periods upperOutliers:## upperOutliers upperFarOut
## 220.5 333.0Graphical Presentation of the Data:
Box Plots of the “maintenance periods” and “cases of carbon brushes replacement”
Low “FarOut” Actually, low farOuts points (days of carbon brush replacement) mean that carbon brushes were replaced on the same day or after few days. In both cases, low farOuts might be entered same information twice- and must be removed from dataset.
Low “FarOut”
## Mill C R brushName brushType phase fromDate toDate Days
## 105 CM4 1 3 C1R03 RC87 U 2010-11-24 2010-12-06 12
## 205 CM4 2 1 C2R01 RC87 V 2010-11-24 2010-12-06 12
## 252 CM4 2 2 C2R02 RC87 V 2010-11-24 2010-12-06 12
## 300 CM4 2 3 C2R03 RC87 V 2010-11-24 2010-12-06 12
## 346 CM4 2 4 C2R04 RC87 V 2010-11-24 2010-12-06 12
## 526 CM4 3 3 C3R03 RC87 W 2010-11-24 2010-12-06 12
## 592 CM4 3 4 C3R04 RC87 W 2010-11-24 2010-12-06 12
## 121 CM4 1 3 C1R03 RC87 U 2015-11-15 2015-11-29 14First quantile - most frequently replaced carbon brushes.
Here, it is easy to find out places, where carbon brushes were replaced significantly more frequently than a majority of carbon brushes of this engine. Presumably, these carbon brushes were affected by local factors (like a local clamping spring) more than common reasons (for this engine).
Fourth quantile - most rarely replaced carbon brushes.
This chart provides information about “frozen” (rarely replaced) carbon brushes. Probably “frozen” brushes have a relatively weak clamping spring - as result, the carbon brush, apparently, did not do the job at all. -For example carbon brushes C2R2 and C3R2 - were not deteriorated more than two years - it is really good situation relatively to the other cement milles (The criterion for replacement is the size (deterioration) of the carbon brush).
We should take into account, that there are upper outliers in the maintenance list - the reason for extremely long intervals between maintenance is probably data loss of maintenance cases:
## dateDiff fromtDate toDate
## 1 82 2005-01-06 2005-03-29
## 2 78 2008-09-17 2008-12-04
## 3 362 2008-12-04 2009-12-01
## 4 39 2011-12-11 2012-01-19
## 5 61 2013-07-30 2013-09-29
## 6 528 2013-12-19 2015-05-31
## 7 161 2016-05-26 2016-11-03
## 8 43 2017-03-06 2017-04-18There is a chance that deteriorated carbon brushes had been replaced during those periods, but we have no information - and as result, we see the lifespan of them as outliers:
## brushName fromDate toDate Days
## 1 C1R01 2004-05-23 2005-08-15 449
## 2 C1R01 2008-08-19 2010-01-24 523
## 3 C1R01 2010-12-06 2011-08-02 239
## 4 C1R01 2013-10-22 2015-07-21 637
## 5 C1R02 2008-08-24 2010-04-25 609
## 6 C1R02 2010-12-06 2011-08-02 239
## 7 C1R02 2013-12-19 2015-07-21 579
## 8 C1R03 2008-08-24 2010-01-24 518
## 9 C1R03 2013-10-22 2015-07-21 637
## 10 C1R04 2004-08-18 2005-07-27 343
## 11 C1R04 2008-08-19 2010-01-24 523
## 12 C1R04 2013-10-22 2015-07-21 637
## 13 C2R01 2004-02-05 2004-11-14 283
## 14 C2R01 2008-08-19 2010-01-24 523
## 15 C2R01 2013-10-22 2015-06-28 614
## 16 C2R02 2004-07-26 2005-03-29 246
## 17 C2R02 2005-09-08 2006-05-21 255
## 18 C2R02 2008-08-19 2010-04-25 614
## 19 C2R02 2013-05-07 2015-06-28 782
## 20 C2R03 2008-08-24 2010-01-24 518
## 21 C2R03 2011-09-18 2012-07-09 295
## 22 C2R03 2013-03-12 2013-10-22 224
## 23 C2R03 2013-10-22 2015-06-28 614
## 24 C2R04 2008-08-24 2010-01-24 518
## 25 C2R04 2013-10-22 2015-06-28 614
## 26 C3R01 2004-11-14 2005-09-08 298
## 27 C3R01 2008-08-19 2010-01-26 525
## 28 C3R01 2013-09-29 2015-06-28 637
## 29 C3R02 2004-01-21 2005-01-06 351
## 30 C3R02 2005-01-06 2005-08-15 221
## 31 C3R02 2008-08-19 2010-01-26 525
## 32 C3R02 2013-05-07 2015-06-28 782
## 33 C3R03 2004-10-03 2005-08-15 316
## 34 C3R03 2008-08-24 2010-01-24 518
## 35 C3R03 2010-12-06 2011-08-02 239
## 36 C3R03 2013-11-25 2015-06-28 580
## 37 C3R04 2004-08-18 2005-03-29 223
## 38 C3R04 2008-08-24 2010-01-24 518
## 39 C3R04 2010-12-06 2011-08-02 239
## 40 C3R04 2013-11-25 2015-06-28 580In order to exclude the uncertainty- whether carbon brushes lifespan outliers are true, or results of information loss- we can test which of these time periods are overlapping (outliers of periods between maintenance and outliers of periods between carbon brushes replacement).
According to the table, except of C1R01(3), C1R02(6), C2R01(13), C2R02(17), C3R03(35), C3R04(39) other lifespan outliers might be a result of the lost information. For example, it looks like carbon brush C2R02 was not replaced more than two years, but this period is overlapped with two periods of lost information, during which carbon brushes might have been replaced for several times.
For sure, we can only say, that only six (C1R01(3), C1R02(6), C2R01(13), C2R02(17), C3R03(35), C3R04(39)) out of forty carbon brushes were not replaced during the regular for this mill period of time (58 days-median).Except for those six cases, other 34 outliers are better to be removed from the dataset.
In the same way possible to analyze current data in order to predict probable problem (“burned” or “frozen” carbon brushes). This chart is based on current data, taken at March 2018.
“Importance” (to put attention) provides visual information about the number of days since last replacement- lower than second quintile, or upper then third quintile. The importance is calculated by the following principles: Maximum value - 10, is equivalent to the maximum distance from the second quantile down (for the low values -“burned” brushes) and from the third quantile up (for the upper values- “frozen” brushes) found in the whole engine history. The minimum value “1” - the number of days since last replacement, lays in the second or third quantiles.
Colors: green- the number of days since last replacement lays in third or second quintile;
red- “burned” brush - the number of days since last replacement and lifetime of the previous brush in this place lay in the first quintile;
blue- “frozen” brush- the number of days since last replacement lays in the fourth quintile.