Template:Rotation: Difference between revisions

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=== Standby Rotation===
#REDIRECT [[Example_Using_SCT_for_Standby_Rotation]]
 
==== Purpose  ====
 
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.''
 
More specifically, the following settings are illustrated:
#State Upon Repair: Default OFF unless SCT overridden
#Activate a block if any item from these associated maintenance group(s) goes down<br>
 
==== Statement ====
 
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.
 
==== BlockSim Solution  ====
 
The BlockSim model of this system is shown in the figure below.
 
[[Image:Blocksim Example Rotation example.png|thumb|center|361px]]
 
 
 
*The failure distributions of all three blocks follow a Weibull distribution with Beta = 1.5 and Eta = 1,000 hours.
*The repair distributions of the three blocks follow a Weibull distribution with Beta = 1.5 and Eta = 100 hours.
*After repair, the blocks are "as good as new."
 
 
There are three maintenance groups, 2_A, 2_B and 2_C, set as follows:
 
 
*Block A belongs to maintenance group 2_A.
**It has a state change trigger.
***The initial state is ON and the state upon repair is "Default OFF unless SCT 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 a state change trigger.
***The initial state is OFF and the state upon repair is "Default OFF unless SCT 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 a state change trigger.
***The initial state is OFF and the state upon repair is "Default OFF unless SCT 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.
 
==== System Events  ====
 
 
 
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:
 
#At 73 hours, Block A fails and activates Block B.
#At 183 hours, Block B fails and activates Block C.
#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.
#At 238 hours, Block A is done with repair. At this time, Block C is operating. Thus Block A is standby.
#At 349 hours, Block C fails and activates Block A.
#At 396 hours, Block A fails and activates Block B.
#At 398 hours, Block C is done with repair. At this time, Block B is operating. Thus Block C is standby.
#At 432 hours, Block A is done with repair. At this time, Block B is operating. Thus Block A is standby.
#At 506 hours, Block B fails and activates Block C.
#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.
#At 560 hours, Block A fails and activates Block B.
#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.
#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.
#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.
 
 
 
[[Image:Block Up Down plot for rotation example.png|thumb|center|500px]]
 
[[Category:BlockSim_Examples]]

Latest revision as of 09:37, 31 July 2012

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