Engine Carbon Brushes Replacement-
Cement Mill 1
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 1 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 1 (February 2004 - February 2018)## Maintaneince days summary:## Min. 1st Qu. Median Mean 3rd Qu. Max.
## 1.00 24.00 27.00 29.97 29.50 514.00##
## Maintaneince days Outleirs:## lowerFarOut lowerOutliers upperOutliers upperFarOut
## 7.50 15.75 37.75 46.00##
## Replacement periods summary:## Min. 1st Qu. Median Mean 3rd Qu. Max.
## 11.0 192.2 364.5 409.4 581.0 1888.0##
## Replacement periods upperOutliers:## upperOutliers upperFarOut
## 1164.125 1747.250Graphical 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
## 84 CM1 1 7 C1R07 CM-2 U 2015-05-21 2015-06-01 11
## 113 CM1 1 9 C1R09 CM-2 U 2015-05-21 2015-06-01 11
## 166 CM1 2 4 C2R04 CM-2 V 2015-05-21 2015-06-01 11
## 221 CM1 2 10 C2R10 CM-2 V 2015-05-21 2015-06-01 11
## 232 CM1 3 1 C3R01 CM-2 W 2015-05-21 2015-06-01 11
## 258 CM1 3 3 C3R03 CM-2 W 2015-05-21 2015-06-01 11
## 286 CM1 3 5 C3R05 CM-2 W 2015-05-21 2015-06-01 11
## 301 CM1 3 6 C3R06 CM-2 W 2015-05-21 2015-06-01 11
## 308 CM1 3 7 C3R07 CM-2 W 2015-05-21 2015-06-01 11
## 319 CM1 3 8 C3R08 CM-2 W 2015-05-21 2015-06-01 11
## 243 CM1 3 2 C3R02 CM-2 W 2013-08-13 2013-08-26 13
## 256 CM1 3 3 C3R03 CM-2 W 2013-08-13 2013-08-26 13
## 284 CM1 3 5 C3R05 CM-2 W 2013-08-13 2013-08-26 13First 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 C1R6 - was not deteriorated more than three years. C3R09 and C3R10 - it looks like they were not replaced for about five 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 40 2006-10-04 2006-11-13
## 2 514 2013-12-23 2015-05-21
## 3 156 2016-05-31 2016-11-03
## 4 56 2017-01-31 2017-03-28
## 5 45 2017-04-30 2017-06-14There 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 C1R06 2012-07-18 2015-12-28 1258
## 2 C2R08 2012-05-01 2015-12-06 1314
## 3 C2R09 2011-12-13 2016-01-19 1498
## 4 C3R02 2008-12-23 2012-03-29 1192
## 5 C3R03 2010-03-02 2013-07-15 1231
## 6 C3R07 2011-12-13 2015-05-21 1255
## 7 C3R09 2012-07-18 2017-09-18 1888
## 8 C3R10 2012-07-18 2017-07-12 1820In 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 C3R02 and C3R03, other lifespan outliers might be a result of the lost information. For example, it looks like carbon brush C3R09 was not replaced for about five years, but this period is overlapped with four periods of lost information, during which carbon brushes might have been replaced for several times.
For sure, we can only say, that C3R03 and C3R02 carbon brushes were not replaced more than three years. Except for those two cases, other outliers are better to be removed from the dataset.
In the same way it is 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.