This week you’re not repairing a sequence. Athion now keeps every revision of a design, so the job is finding which change broke the start.
Since V3 went live, the reflux start holds every time. P-203 never starts.
C-203's reflux start ran clean for months. Three changes went in between V1 and V3, and now it stops at the pump.
Run both versions, then open each change to see what it did.
Which change stops the reflux start?
Watch the drum level when V3 moves on from the fill step. What is P-203's interlock waiting for?
| Tag | Service | Type |
|---|---|---|
| LT-0101 | TK-101 level | AI |
| TT-101 | TK-101 temp | AI |
| FV-101 | Inlet, fail closed | DO |
| P-101 | Transfer pump | DO |
| Cause | FV-101 | P-101 |
|---|---|---|
| LSHH-102 high-high | O | – |
| LT-101 low-low | – | S |
O open · C close · S stop
Athion now reads drawings and documents against each other. Try it by hand first: three documents, one tank, three places they disagree.
Three documents describe TK-101. A change is coming, and nobody is sure they agree.
Find the three places they disagree.
Tap anything that looks off, in any document.
Athion now captures every variable in the plant, plus operator actions and configuration changes. Play detective with one night on Unit 200.
PAH-201 high pressure alarmed at 05:52. Night shift says nothing unusual happened.
Five things happened on Unit 200 overnight. Athion captured every one: the trend, the operator actions and a configuration change.
Which change explains this morning's alarm?
Find when the pressure first stops looking calm. What happened just before?