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Registers

Range, Alarm and Trip Schedule

RATS

The RATS is the single place where the calibrated range, the alarm limits and the trip settings live together. Keeping them together is the point: an alarm set outside the transmitter range never annunciates, and that error is invisible unless the two numbers sit side by side.

Do you need this one?

Any system with analog measurement. It is also the document a regulator or an insurer asks for when reviewing protective functions.

What is in it

  1. 01Instrument identity and calibrated range
  2. 02Alarm limits with priority
  3. 03Trip settings and action
  4. 04Deadband and delay
  5. 05Calibration record

Written by

Control systems engineer

Approved by

Process owner

Written against

  • ISA-18.2 for alarm management
  • IEC 61511 for trip settings

Preview

RATS.csv
Tag,Service,Instrument Type,Signal,Cal Range Low,Cal Range High,Units,Normal Operating Low,Normal Operating High,LL Trip,L Alarm,H Alarm,HH Trip,Deadband,Delay s,LL Priority,L Priority,H Priority,HH Priority,Trip Action,Cause Ref,Calibrated By,Cal Date,Cal Due,Cert No
FT-101,Feed flow,Magnetic flow meter,4-20mA,0,50,m3/h,15,35,,5,45,,1,10,,Medium,Medium,,Sequence hold,C-006,,,,
LT-101,Feed tank level,Radar level,4-20mA,0,100,%,20,80,5,10,90,95,2,2,High,Medium,Medium,High,Pump stop and valve close,C-003 C-004,,,,
TT-101,Reactor temperature,RTD Pt100,RTD,0,200,degC,120,160,,100,150,180,2,0,,Low,Medium,High,Master trip,C-005,,,,
PT-101,Reactor pressure,Pressure transmitter,4-20mA,0,10,barg,2,6,,1,7,8,0.2,1,,Medium,High,High,Master trip,,,,,
AT-101,Product concentration,Analyser,4-20mA,0,100,%,45,55,,40,60,,0.5,30,,Low,Low,,Alarm only,,,,,

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