How to incorporate non-operational hours in a MTBF/MTTR

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elizabeth.l asked May 24, '18 elizabeth.l answered Jun 30, '18

How to incorporate non-operational hours in a MTBF/MTTR

I have a processor on a timetable. It is assigned to a MTBF/MTTR with variable First Failure, Up, and Down Times.

There are times when the processor goes down at the end of the day making it so the down time extends into non-operational hours. This can also happen if the down time is longer than a shift.

I have down times specified as working hours/days so I need a way to "pause" the down time during non-operational hours.

I saw a similar post (https://answers.flexsim.com/questions/39254/how-to-make-a-mtbf-follow-a-time-table.html), but the 2 suggestions won’t work in my case. A time table isn’t feasible because of the variability, and checking the state won't work since I’m not just trying to prevent down time from starting during non-operational hours, I’m also trying to “pause” the down time during non-operation hours.

The only solution I thought might work, is to look ahead in the schedule and inflate the down time to include non-operational hours. Any other ideas?

Software Version:

FlexSim 17.1.6

mtbf mttr timetable

Answer 1 · 2018-05-25T03:58:08Z

asb.p answered May 25, '18 tannerp commented Jun 25, '18

Hello Elizabeth,

As per my understanding of your question, We can make breakdown state specific. For example your processor will breakdown only when it is processing or busy or setup then you can set the breakdown apply only to those states as shown in the below picture. All all the states in which breakdown is possible. At the end of the shift your processor will be in scheduled down as schduled down is not listed in the stated applied to MTBF, breakdowns will not happen in those stated.

Thanks,

Praneeth.

mmtrmtbf.jpg (51.7 KiB)

· 2

elizabeth.l commented · May 30, 2018 at 05:19 PM

Attached is a very specific example in version 18.1.

The processor is on a schedule where work days are 9 hours, 8-5pm.
There's an MTBF/MTTR that starts on the second day at 9 am (First Failure Time = 10 hours). The down time is 10 hours.

I print out a message in the On Break Down and On Repair Triggers. Notice the repair time is during non-operational hours.
On Break Down: 9:00:00 AM 5/30/2018
On Repair: 7:00:00 PM 5/30/2018

The state bar shows 8 hours of breakdown not 10. I'd like to see 10 hours, so something like this, where the last 2 hours are completed on the following day.
On Break Down: 9:00:00 AM 5/30/2018
On Repair: 10:00:00 AM 5/31/2018

Is it possible to do this? Am I missing something?

Thanks,

Elizabeth

mtbf-mttr.fsm

0 ·

mtbf-mttr.fsm (27.3 KiB)

tannerp elizabeth.l commented · Jun 25, 2018 at 07:41 PM

@elizabeth.lopez have you resolved this issue with the MTBF-MTTR?

0 ·

Answer 2 · 2018-06-30T04:50:10Z

elizabeth.l answered Jun 30, '18

I didn't exactly. I ended up adjusting the First Failure and Up Time so that breakdowns occurred first thing in the morning. That way all activities could be completed by the end of the work shift and did not continue to run into the eveining.

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