Method
Interval rate = (current value − previous value) / elapsed time × selected time base
A rise is flagged when the interval rate is greater than the declared positive limit. A fall is flagged when the rate is less than the negative of the declared fall magnitude.
Interpretation
Short intervals, coarse instrument resolution, unfiltered noise, and clock errors can create large apparent rates. Control systems often evaluate rate over a configured period or apply filtering and deadband. Match those details before comparing this retrospective screen with an alarm.
Worked example and limitations
The sample's largest rise is 32 units/hour and largest fall is −40 units/hour. Against limits of +25 and −30, two intervals are flagged. This tool does not configure an alarm, validate a trip, diagnose a cause, or authorize continued operation.