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{{Template:BSExampleSim| Example 5}}
#REDIRECT [[Example_Using_SCT_for_Standby_Rotation]]
 
== Rotation Example  ==
 
==== Purposes  ====
 
The purposes of this example is to illustrate the following options in SCT:
 
#State Upon Repair: Default OFF unless SCT overridden<br>
#Activate a block if any item from these associated maintenance group(s) goes down<br>
 
==== Description  ====
 
Three devices A, B and C are in parallel and rotate to perform the task. A is ON initially, B and C are standby. When A fails, Turn B On; when B fails, turn C ON and when C fails, Turn A ON. The desired situation is that, at every moment, one and only one device is operating. This means that, when a device is done with repair, it should be standby if there is already one device operating; or it should be operating when there is not device operating.
 
==== BlockSim Solution  ====
 
The Blocksim modeling of this system is shown in Figure below.
 
[[Image:Blocksim Example Rotation example.png]]
 
The failures of all three blocks follow Weibull distribution with Beta = 1.5 and Eta = 1000. The repair durations of three blocks follow Weibull distribution with Beta = 1.5 and Eta = 100. After repair, they are as good as new. <br>
 
Block A belongs to maintenance group 2_A. It has state change trigger. The initial state is ON and the state upon repair is "Default Off Unless overridden". If any item from maintenance group 2_C goes down, then activate this block.
 
Block B belongs to maintenance group 2_B. It has state change trigger. The initial state is OFF and the state upon repair is "Default Off Unless overridden". If any item from maintenance group 2_A goes down, then activate this block.
 
Block C belongs to maintenance group 2_C. It has state change trigger. The initial state is OFF and the state upon repair is "Default Off Unless overridden". If any item from maintenance group 2_B goes down, then activate this block.
 
All blocks A, B and C are as good as new after repair.
 
==== Block Up/Down plot  ====
 
The system event log is shown in Figure below and is as follows:<br>
 
#At 73, Block A fails and activates Block B.
#At 183, Block B fails and activates Block C.
#At 215, Block B is done with repair. At this time, Block C is operating, according to setting, Block B is standby.&nbsp;
#At 238, Block A is done with repair. At this time, Block C is operating. Thus Block A is standby. <br>
#At 349, Block C fails and activates Block A.
#At 396, Block A fails and activates Block B.
#At 398, Block C is done with repair. At this time, Block B is operating. Thus Block C is standby.
#At 432, Block A is done with repair. At this time, Block B is operating. Thus Block A is standby.
#At 506, Block B fails and activates Block C.
#At 515, Block B is done with repair and keep standby because Block C is operating.
#At 536, Block C fails and active Block A.
#At 560, Block A fails and active Block B.
#At 575, Block B fails and put a requset to active Block C. However, Block C is under repiar at the time. Thus when Block C is done with repair at 606, the OFF setting is overwritten and it is operating immdediatly.&nbsp;
#At 661, Block C fails and put a request to active Block A. However, Block A is under repair at the time. Thus when Block A is done with repair at 699, the OFF setting is overwritten and it is operating immdediatly. <br>
#Block B and Block C are done with repair at 682 and at 746 respectively. However, at these two time point, Block A is operating. Thus they are both standby upon repair according to settings.
 
[[Image:Block Up Down plot for rotation example.png]]
 
[[Category:BlockSim_Examples]]

Latest revision as of 09:37, 31 July 2012

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