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Standby Redundancy

Creator
Creator

Dear All,

I am modeling a permutation flow line in plant simulation. I attached the file to this post and added the corresponding labels in brackets.

My problem is that I want to include standby redundancy (standbyRed) for the second machine (mach2). To do so I implemented a method (activateStandby). When I manually set machine 2 to failed state everything works perfectly. The preceding buffer (Buffer1) gives all MUs to the redundant machine. Nevertheless, when I fail machine 2 by defining a failure profile (compare to profile in attachment) the method will not work. The only possible explanation I can imagine so far is, is that the failure profile is not failing machine 2 for some reason.

Help is greatly appreciated, thank you very much.

Cheers

Philipp

8 REPLIES

Re: Standby Redundancy

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor
the way you setup the failure causes only one failure; better set an availability e.g. 95 and a main repair time (MTTR) of e.g. 5 minutes (this will generate a lot of failures during the experiment run). Then your model is running.
Steffen Bangsow
freelance simulation specialist  
web: www.bangsow.eu
mail: steffen@bangsow.net

Re: Standby Redundancy

Creator
Creator

Dear Steffen,

Thank you for getting back to me so quickly!

I defined the failure profile as you recommended but the first buffer (buffer1) will still not switch to passing the MUs on to my redundant machine (StanbyRed). Any ideas what else the reason could be?

Further, I used the singular failure because I want to model downtime due to maintenance work.

Re: Standby Redundancy

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor
you need to set a duration of the failure > cycletime, so that the failure not happens between the cycles.
Set a breakpoint in the method, so you can better see what is happen.
And check the statistics of the bypass!
Steffen Bangsow
freelance simulation specialist  
web: www.bangsow.eu
mail: steffen@bangsow.net

Re: Standby Redundancy

Creator
Creator

I gave it a try with process times of all machines equaling 1:00, failure start at 4:00 and failure duration of 1:20:00. Still it is not working. When I check the statistics for the standby machine after 1:40:00 it says 70% Waiting, 30% Pause, 0% Working.

Re: Standby Redundancy

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor
can you post you model again?
Steffen Bangsow
freelance simulation specialist  
web: www.bangsow.eu
mail: steffen@bangsow.net

Re: Standby Redundancy

Creator
Creator

Sure, Thank you!

Re: Standby Redundancy

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

what happens: the failure starts after the calling of the exit control, so the condition was false; then the failure starts --> the parts keeps on the machine.

This will not happen, if you set a waituntil to wait for defined states of the machine.

This helps:

 

is
do
	waituntil  mach2.failed or (mach2.empty and mach2.operational) prio 1;
	if mach2.failed=true then
		@.move(StandbyRed);
	else
		@.move(mach2);
	end;
end;

 

 

Steffen Bangsow
freelance simulation specialist  
web: www.bangsow.eu
mail: steffen@bangsow.net

Re: Standby Redundancy

Creator
Creator
Now it works, thank you very much!