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| === Standby Rotation===
| | #REDIRECT [[Example_Using_SCT_for_Standby_Rotation]] |
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| ==== Purpose ====
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| This example illustrates the use of state change triggers ([http://www.reliawiki.org/index.php/BlockSim_8:_State_Change_Triggers#State_Change_Triggers SCT]) in BlockSim Version 8 by using a simple standby configuration. ''Note that this example could also be done using the standby container functionality in BlockSim.''
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| More specifically, the following settings are illustrated:
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| #State Upon Repair: Default OFF unless SCT overridden
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| #Activate a block if any item from these associated maintenance group(s) goes down<br>
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| ==== Statement ====
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| Assume three devices A, B and C in a standby redundancy (or only one unit is needed for system operation). The system begins with device A working. When device A fails, B is turned on and repair actions are initiated on A. When B fails, C is turned on and so forth.
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| ==== BlockSim Solution ====
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| The BlockSim model of this system is shown in the figure below.
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| [[Image:Blocksim Example Rotation example.png|center|150px]]
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| *The failure distributions of all three blocks follow a Weibull distribution with Beta = 1.5 and Eta = 1,000 hours.
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| *The repair distributions of the three blocks follow a Weibull distribution with Beta = 1.5 and Eta = 100 hours.
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| *After repair, the blocks are "as good as new."
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| There are three maintenance groups, 2_A, 2_B and 2_C, set as follows:
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| *Block A belongs to maintenance group 2_A.
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| **It has a state change trigger.
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| ***The initial state is ON and the state upon repair is "Default OFF unless SCT overridden."
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| ***If any item from maintenance group 2_C goes down, then activate this block.
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| *Block B belongs to maintenance group 2_B.
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| **It has a state change trigger.
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| ***The initial state is OFF and the state upon repair is "Default OFF unless SCT overridden."
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| ***If any item from maintenance group 2_A goes down, then activate this block.
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| *Block C belongs to maintenance group 2_C.
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| **It has a state change trigger.
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| ***The initial state is OFF and the state upon repair is "Default OFF unless SCT overridden."
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| ***If any item from maintenance group 2_B goes down, then activate this block.
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| *All blocks A, B and C are as good as new after repair.
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| ==== System Events ====
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| The system event log for a single run through the simulation algorithm is shown in the Block Up/Down plot below, and is as follows:
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| #At 73 hours, Block A fails and activates Block B.
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| #At 183 hours, Block B fails and activates Block C.
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| #At 215 hours, Block B is done with repair. At this time, Block C is operating, so according to the settings, Block B is standby.
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| #At 238 hours, Block A is done with repair. At this time, Block C is operating. Thus Block A is standby.
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| #At 349 hours, Block C fails and activates Block A.
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| #At 396 hours, Block A fails and activates Block B.
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| #At 398 hours, Block C is done with repair. At this time, Block B is operating. Thus Block C is standby.
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| #At 432 hours, Block A is done with repair. At this time, Block B is operating. Thus Block A is standby.
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| #At 506 hours, Block B fails and activates Block C.
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| #At 515 hours, Block B is done with repair and stays standby because Block C is operating. | |
| #At 536 hours, Block C fails and activates Block A.
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| #At 560 hours, Block A fails and activates Block B.
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| #At 575 hours, Block B fails and makes a request to activate Block C. However, Block C is under repair at the time. Thus when Block C is done with repair at 606 hours, the OFF setting is overridden and it is operating immediately.
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| #At 661 hours, Block C fails and makes a request to activate Block A. However, Block A is under repair at the time. Thus when Block A is done with repair at 699 hours, the OFF setting is overridden and it is operating immediately.
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| #Block B and Block C are done with repair at 682 hours and at 746 hours respectively. However, at these two time points, Block A is operating. Thus they are both standby upon repair according to the settings.
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| [[Image:Block Up Down plot for rotation example.png|center|250px]]
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| [[Category:BlockSim_Examples]] | |