BlockSim Example: Default ON unless SCT Overridden

Default ON unless SCT overridden Example

Purposes

The purposes of this example are to illustrate the following options in SCT:

1. State Upon Repair: Default ON unless SCT overridden
   
2. Activate a block if any item from these associated maintenance group(s) goes down
   
3. Deactivate a block if any item from these associated maintenance group(s) is restored

Description

Consider a system shown in Figure below:

Block P is the primary device. It belongs to maintenance group P.

Block S is the standby device. It has state change triggers. The initial state is OFF. If Block P goes down, then activate this block; if Block P is restored, then deactivate this block. The State Upon Repair is “Default ON unless SCT Overridden”.

Both Block P and S have Weibull distribution with Beta=1.5 and Eta=100 for reliability and repair action.

Both Block P and S are as good as new after repair.

Block Up/Down plot

The Blocksim modeling of this system is shown in Figure below.

1. At 123, Block P fails and activates Block S.
2. Block S fails at 186 and is restored at 208. According to setting, it is ON upon repair.
3. At 223, Block S fails again.
4. At 301, Block P is restored, and put a request to deactivate Block S. However, Block S is down for repair at this point. The request overwrites the default setting "state upon repair" of Block S. Thus when Block S is done with repair at 385, it is OFF.
5. At 439, Block P fails and activates Block S.
6. At 523, Block P is restored and deactivates Block S.
7. At 694, Block P fails and activates Block S.
8. At 702, Block S fails and it is get repair at 775. According to setting, it is ON upon repair.
9. At 788, Block P fails and activates Block S.
10. At 845, Block P is restored and deactivates Block S.