PLEXUS EXAMPLE · 07

Alarm list vs instrument index

Twelve alarms checked against the instrument index and the alarm philosophy: orphans, range clashes and priority drift flagged for review.

Input

ALARM LISTACD-ALM-0001

DCS alarm database extract, ACD-300-001

Revision: Rev B
Alarms: 12
Scope: ACD-300-001

INSTRUMENT INDEXACD-REG-0001

Master Tag Registers, Instruments sheet

Revision: Rev 0
Filter: ACD-300-001
Instruments: 10

Instrument existsEvery alarm references a live instrument in the index for this sheet.

Setpoint inside rangeSetpoints sit inside the calibrated range and clear of their trip setting.

Priority per BoDPriorities follow the BoD alarm philosophy: P1 pre-trip, P2 deviation, P3 advisory; alarms at 80% of the normal-to-trip gap.

The source documents are not shown: alarm databases and registers stay inside your project. The check below runs on a hypothetical plant (ACD), presented the way consistency results arrive.

What Plexus does

01Reads the alarm list and the instrument index into one structure.
02Checks each alarm against its instrument: existence, range and trip margin.
03Checks priorities against the BoD alarm philosophy.
04Marks each alarm pass, conflict or check; the engineer confirms and updates the alarm database.

Output

0 / 12 alarms checkedrun first, then export

This animation illustrates the Plexus workflow on a hypothetical plant (ACD). In the product, consistency checks run server-side and every value keeps provenance to its source document; an engineer reviews and confirms.

Source documents: ACD-ALM-0001 Rev B and ACD-REG-0001 Instruments sheet, hypothetical plant

Alarm	Instrument	Setpoint	Priority	Status
PAH-3003V-301 pressure high (pre-trip of SIF-104)	PT-30030-600 kPa(g)	350 kPa(g)	P1	checkThe BoD sets alarms at 80% of the normal-to-trip gap, which computes 410 kPa(g) from 250 normal and 450 trip, while the same section quotes 350 for this alarm. Confirm the rationalization basis.
XA-3005SIS action PSHH-3005, first-out indication	PSHH-3005450 kPa(g)	on SIF demand	P1	pass
TAH-3001E-302 outlet temperature high	TT-30010-150 deg C	55 deg C	P2	pass
TAL-3002E-303 outlet temperature low	TI-3002-20-80 deg C	-25 deg C	P2	conflictSetpoint sits below the -20 deg C range floor of TI-3002; the transmitter clamps before the alarm can operate.
LAH-3004V-301 level high	LT-30040-1600 mm	1400 mm	P2	pass
LAL-3004V-301 level low	LT-30040-1600 mm	200 mm	P2	pass
LAH-3007T-301 level high	LT-30070-1200 mm	1050 mm	P2	pass
LAL-3007T-301 level low	LT-30070-1200 mm	150 mm	P2	pass
AAL-3010H2 export purity low	AI-301080-100 mol% H2	95 mol% H2	P2	pass
FAH-3009H2 export flow high (advisory)	FQI-30090-400 kg/h	360 kg/h	P3	checkAdvisory alarm on a totalized export stream. Confirm it survives rationalization against the BoD alarm-rate target.
TAH-3013E-301 process outlet temperature high	TT-3013not in index	160 deg C	P3	conflictNo TT-3013 in the instrument index for this sheet. The alarm references an instrument that is absent from the register, likely left behind by a revision.
LSHH-3006V-301 level high-high	LSHH-30061500 mm	1500 mm	P3	conflictThe BoD names LSHH-3006 a P1 example; the alarm list carries P3. The downgrade looks like a database edit made without rationalization.

Manual: 2-4 hours
With Plexus: 10-20 min review (estimate, one-sheet alarm list against the instrument index)

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