This module is a part of “Engine Carbon Brushes Replacement” project. The purposes of the module are:
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 12 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 12 (February 2006 - February 2018)
## Maintaneince days summary:
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##    1.00   23.00   28.00   38.76   30.00  880.00
## 
## Maintaneince days Outleirs:
##   lowerFarOut lowerOutliers upperOutliers   upperFarOut 
##           2.0          12.5          40.5          51.0
## 
## Replacement periods summary:
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##    1.00   28.25  110.50  193.99  189.00 2072.00
## 
## Replacement periods upperOutliers:
## upperOutliers   upperFarOut 
##       430.125       671.250

Graphical 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
## 11  CM12 1 1     C1R01      CM5H     U 2010-08-09 2010-08-10    1
## 41  CM12 1 2     C1R02      CM5H     U 2010-08-09 2010-08-10    1
## 97  CM12 2 1     C2R01      CM5H     U 2010-08-09 2010-08-10    1
## 129 CM12 2 2     C2R02      CM5H     U 2010-08-09 2010-08-10    1
## 19  CM12 1 1     C1R01      CM5H     U 2016-10-26 2016-10-30    4
## 47  CM12 1 2     C1R02      CM5H     U 2016-10-26 2016-10-30    4
## 107 CM12 2 1     C2R01      CM5H     U 2016-10-26 2016-10-30    4
## 136 CM12 2 2     C2R02      CM5H     U 2016-10-26 2016-10-30    4
## 313 CM12 4 4     C4R04      CM5H     V 2016-10-26 2016-10-30    4
## 402 CM12 6 1     C6R01      CM5H     W 2010-08-06 2010-08-10    4
## 450 CM12 6 3     C6R03      CM5H     W 2016-10-26 2016-10-30    4
## 471 CM12 6 4     C6R04      CM5H     W 2010-08-06 2010-08-10    4
## 10  CM12 1 1     C1R01      CM5H     U 2010-08-04 2010-08-09    5
## 96  CM12 2 1     C2R01      CM5H     U 2010-08-04 2010-08-09    5
## 209 CM12 3 2     C3R02      CM5H     V 2011-01-09 2011-01-17    8
## 230 CM12 3 3     C3R03      CM5H     V 2011-01-09 2011-01-17    8
## 276 CM12 4 2     C4R02      CM5H     V 2011-01-09 2011-01-17    8
## 406 CM12 6 1     C6R01      CM5H     W 2011-01-09 2011-01-17    8
## 444 CM12 6 3     C6R03      CM5H     W 2011-01-09 2011-01-17    8
## 257 CM12 4 1     C4R01      CM5H     V 2010-07-06 2010-07-17   11


First 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 brush C1R02 - was not deteriorated more than six years (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       46 2010-10-14 2010-11-29
## 2      880 2011-04-15 2013-09-11
## 3      521 2013-12-26 2015-05-31
## 4       51 2015-06-01 2015-07-22
## 5      163 2016-05-16 2016-10-26
## 6       71 2017-02-06 2017-04-18
## 7       41 2017-08-28 2017-10-08
## 8       41 2017-11-22 2018-01-02

There 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 2011-02-23 2016-02-10 1813
## 2      C1R02 2011-02-23 2016-10-26 2072
## 3      C1R03 2011-02-23 2015-06-01 1559
## 4      C1R03 2016-02-10 2017-08-28  565
## 5      C1R04 2011-02-23 2016-02-10 1813
## 6      C2R01 2011-02-23 2013-11-28 1009
## 7      C2R01 2013-11-28 2015-09-16  657
## 8      C2R02 2011-02-23 2015-11-02 1713
## 9      C2R03 2011-02-23 2016-02-10 1813
## 10     C2R04 2011-02-23 2016-02-10 1813
## 11     C3R01 2011-02-23 2013-11-28 1009
## 12     C3R01 2013-11-28 2015-09-16  657
## 13     C3R01 2015-09-16 2016-11-27  438
## 14     C3R02 2011-02-23 2015-06-01 1559
## 15     C3R03 2011-02-23 2016-01-07 1779
## 16     C3R04 2011-02-23 2016-01-07 1779
## 17     C4R01 2011-02-23 2016-02-10 1813
## 18     C4R01 2016-02-10 2017-10-08  606
## 19     C4R02 2011-02-23 2015-07-22 1610
## 20     C4R02 2016-02-10 2017-06-27  503
## 21     C4R03 2011-02-23 2013-11-28 1009
## 22     C4R03 2013-11-28 2015-06-01  550
## 23     C4R04 2011-02-23 2015-11-02 1713
## 24     C5R01 2011-02-23 2016-02-10 1813
## 25     C5R01 2016-02-10 2017-10-08  606
## 26     C5R02 2011-02-23 2013-11-28 1009
## 27     C5R02 2013-11-28 2015-07-22  601
## 28     C5R02 2016-01-07 2017-04-18  467
## 29     C5R03 2011-02-23 2015-06-01 1559
## 30     C5R03 2016-01-07 2017-04-18  467
## 31     C5R04 2011-02-23 2016-01-07 1779
## 32     C6R01 2011-02-23 2013-11-28 1009
## 33     C6R01 2013-11-28 2016-01-07  770
## 34     C6R01 2016-01-07 2017-04-18  467
## 35     C6R02 2011-02-23 2013-11-28 1009
## 36     C6R02 2013-11-28 2015-09-16  657
## 37     C6R03 2011-02-23 2013-11-28 1009
## 38     C6R03 2013-11-28 2015-11-02  704
## 39     C6R04 2011-02-23 2016-01-07 1779

In 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, all lifespan outliers might be a result of the lost information. For example, it looks like carbon brush C1R02 was not replaced for about six years, but this periods are overlapped with four periods of lost information, during which carbon brushes might have been replaced for several times.

All 39 outliers are better to be removed from the dataset.

Current condition
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.