MTBF Calculation/Expression

[Sam_Thomas]

Hi

I am wondering if someone could help me with an Expression. 

I am trying to create a chart showing the MTBF (Mean Time Before Failure) figure for each site. With the worst sites 10 sites visible. 

Context: I want to show the average amount of time (in hours) a piece of equipment runs for before it requires some repair work / a reset. This will be based on the last 4 years of data. 

Fields - 

Creation_Date (when the job was raised)

Completion_Date (when the job was closed/finished)

Job_Number

Equipment_Number

Any assistance would be appreciated. Thanks. 

[Or]

Sounds like you need four years worth of hours (added one for Feb 29th every four years): ((4 * 365 * 24)+1) / count(distinct [Job_Number]) with Equipment as your dimension, assuming "Job" refers to the equipment being repaired or reset. If you have equipment that hasn't been available for the past four years, you'll need a different set of hours, but since your data doesn't seem to contain any information about how long the equipment has been available, there's no way to write that into the formula.

[Sam_Thomas]

Thanks for the reply. 

The formula I need will be (Total Time - Total Down Time /  Number of Jobs).

To work out the down time for each job: (Completion Date - Creation Date)

I need to then sum these values per piece of equipment to give me the total down time for the total period for each piece of equipment. 

Then I need to divide this number by the total number of jobs raised for that piece of equipment. I just can't work out how to put it all together in a graph. 

[Or]

Total time - your data has no way to work this out at the moment, so unless you have additional information, probably the best you can do is the calculation I used for four years worth of hours.

(Sum(Completion_Date - Creation_Date)*24) should give you the total down time in hours (default is days, iirc, so multiply by 24 to get hours)

Count (Job_Number) should give you the total number of jobs.

So, with a dimension of Equipment, the end formula should be

(((4 * 365 * 24)+1)

- 

(Sum(Completion_Date - Creation_Date)*24))

/

count(distinct [Job_Number])

If you do have a way to calculate the total amount of available equipment time, you can use that to replace the first part.