Is it a Big BUG Block Sim Ver 6210 Built Dec 2004

[Rajesh Goyal]

(1) How to give Failure Distribution and its parameters for components placed inside a container?
(2) When I am creating a `Load Sharing Container' and putting components in it, and assigning any distribution other than Weibull, after Analysis if I am viewing `System Reliability Equation' I am getting Weibull with parameters Beta=1.5, Eta=1000 and Gamma=0 under `Block Failure Distribution Legend. Where is the mistake?
(3)Also, in `Load and Life Parameter Experimenter' ( Life Stress Relationship - Inverse Power Law and Distribution - Exponential is selected) if (incorrect) values are given like (for example) First value 10 & 100 and second values 20 & 200, On clicking `Calculate' it gives k=0.0050 and n=0; and when we press `Update' it gives a wrong message `K must be greater than 0' where as k is > 0. Please check.

[Rajesh Goyal]

First 2 problems are solved, ther is no problem and now I can do it. But the third is YES! it is a Bug. No responce from Software Support Team yet.

[tarik]

This seems to be a bug, I will address this to our development team and hopefully we’ll have a fix soon.
If you have the ALTA software, you can perform this kind of analysis.
I have a remark: it seems that for the values you provided, you don’t have stress actually. You are not using the container as a way to create hierarchy in your diagram (sub-diagrams), are you?

[Rajesh Goyal]

I have not understood what you want to convey in 2nd part of your remark. Please eleborate with an example if possible.

[tarik]

Because of the values you specified (which show no stress), it seemed that component does not experience higher stresses if another component fails, meaning these components are not in a load sharing situation. Therefore I was wondering whether you were doing that on purpose because you want to use the container as a sub-diagram, or a way to encapsulate a diagram or RBD inside another diagram or RBD

[Rajesh Goyal]

Service Release 6.2.13: Please refer my previous discussions

I used BlockSim Ver 6.2.10 Build 17, December 2004 for block simulation. For my large system I am not able to understand the following:

I have an electrical system (I have defined it as standby container) which has two components- (1) Main control panel and (2) Remote control panel (I have put these two in the container and `Remote control panel’ is `Active’ with exponential failure distribution and Main Panel as `Stand by’ with exponential failure distribution again)
Now if I consider this as a complete system, why I have to define `Block can fail’ in Reliability Properties page of Container Properties? (In my opinion failure should be inherited by components in side the container). In case I don’t, i.e. If not selected, the reliability of the switch is considered to be 100%, whereas this is not the case. Reliability will depend on failure distribution of panel-1 or panel-2. Reliability equations and legend given in this case are more confusing? I am totally not in position to find correct solution because of incorrect representation by the software. Please guide me how to overcome with this problem so that I can do correct simulation and results.
Check the equations I am getting:

RSystem=+RElectrical System
Block Failure Distribution Legend
Electrical System: Switch Cannot Fail
Remote Control Panel: Exponential Mu = 54854 Gamma=0
Main Control Panel: Exponential Mu=14961 gamma=0


I have an objection on declaring `switch cannot fail’ when both the components have valid failure distribution and can fail simultaneously (i.e. `active’ component fails and `standby’ also fails after switching).


Now today, I have downloaded the service release 6.2.13 and carried-out the same analysis. The point remains the same; the inherited failure of container is not explained in this too. You have just removed the container blocks failure distribution details that belong to Stand-by or Load Sharing containers. The following new output is not better than the previous one.

frSystem=+frElectrical System
Block Failure Distribution Legend
Electrical System: Switch Cannot Fail

“Switch Cannot Fail” ? why? Submitted for comments and guidance please.

[Lance.Larson]

Thank you for your questions. The most recent Service Release of the BlockSim 6 software changes the way that containers appear in the System Reliability Equation. However, it does not alter the results. It is merely a change in the display so that the individual blocks inside a container will no longer appear. This is by design and not a bug. The container is still inheriting the reliability of the blocks inside the container.

I also wanted to point out that the Container block can only fail in cases where there is a Stand-by Container. When you are using a Load Sharing Container, the Reliability and Maintainability tabs disappear. The Reliability for a Stand-by Container is used to specify an additional probability of failure if warranted by the system configuration.

Regarding your question on the switch, this too is by design. There is a probability of a Stand-by block not coming on line when the Active block fails. This probability is modeled by the Switch Action Reliability. The reliability of the blocks in questions has no bearing on the Switch. As you mentioned, when the Stand-by block has a Quiescent distribution. By using this Quiescent failure probability, you may indeed have both blocks fail at the same time or even have the Stand-by block fail before the Active block. The switch reliability would have no impact on that.

Finally, I wanted to refer you to pages 201 and 227-239 in your BlockSim 6 Users Guide for more specifics on the containers. I hope that this helps answer your questions. Please let me know if you need any clarification or if you have additional questions.

[Rajesh Goyal]

Dear Lance,
Thank you very much for your comments and references for study which I missed somehow in my first reading. I have one suggestion, the previous representation of Ver 6.2.10 Build 17, December 2004, was better in the sense that it used to give failure distribution details of contained components also in Block Failure Distribution Legend.

Now, the reference is made to Hot Wire eMagazine Issue 48, Feb 2005, in which Analyzing Systems that do not operate 24 hours per day is explained using BlockSim. My analysis is exactly of the same nature, but I don’t know how to use BlockSim for adjustments that are necessary in order to interpret the results appropriately, i.e getting different plot type with adjustments and for interpreting the simulation results in the same way. I want to have simulation plots for point reliability, availability and both reliability and availability using BlockSim with adjustment of system down time for number of hours/day due to the off-hours, and also, analytical plots for Reliability vs Time etc.

Please provide some guidance and further suggest reference for reading. I am planning to attend your symposium in Singapore on 18-19 Aug 05, If you are attending the same we will interact during seminar too.

[Rajesh Goyal]

Is it possible to have selected blocks while generating Reliability Importance vs Time plot. For Example if I have 13 Blocks, and I am interested in 5 Blocks for RI vs Time plot. I have tried following with no success:
(a) set block to off
(b)set block flag options

[tarik]

There is no easy way to do what you are trying to accomplish. You can uncheck the ‘Block Can Fail’ Option and re-plot. However you will have to use the RS Draw feature to delete references to the unselected blocks in the legend.

[Rajesh Goyal]

Thanks Tarik for your suggestion. I tried this way but the problem now I am facing is, I am not able to identify references to the legend, as after 10 Lines color is repeated by the system. I dont't find any way to introduce more lines or lines with different Markers. Is it the limitation of your software?

[tarik]

You can use the Plot Setup (under the ‘Lines’ tab) feature to change line thickness/type/color. Note though that you can increase the thickness of a line if it’s not a solid line (i.e. you can’t increase the thickness of a dashed line for ex). For further modification in the plot, you can use the RS Draw feature.

[Rajesh Goyal]

Tarik, I am not able to make my problem very clear it appears. Changing Line thickness is not solving my problem. If I change Line thickness for Line-1 which is representing sub-system-A (say), then Line-11 also changing it thickness to the same (and same color) which is representing sub-system-K. So I don't know on the plot which is my sub-system-A and which is K.
Please find Attachment to help me
Rajesh <center><table border=1><tr><td>http://63.227.80.170/discus/icons/attachment_icon.gifReliability Importance Vs Time Plot
ForReliaSoft.WMF (http://63.227.80.170/discus/messages/96/ForReliaSoft-542.unk) (32.0 k)</td></tr></table></center>

[tarik]

You can use the RS Draw to make the necessary changes to further differentiate between the lines. Note also that clicking on the line displays a text box that contains an identification of the line.

[Rajeshj Goyal]

Sorry Tarik its not working this way too. I am sending the attachment in which I have changed the line style to dotted (Red) but It's not showing any identification. Even it has not changed in Legend too. May I request ReliaSoft to provide solution
Rajesh