Frozen check

The Frozen Check detects when field equipment is "stuck" recording the same value.

This check applies to Primary History Granularity (PHG), but can also be enabled in the Hourly Data Validation and the Daily Data Validation checks.

The following algorithm is used to detect if the sensory equipment is frozen:

Where:

• Valt = The most recent measurement data at time t.

• Valt-n = Measurement data n scan intervals ago.

• n = Number of user-configured consecutive readings.

• Tol = Tolerance (% error) acceptable for the data check. If the algorithm returns a true condition, an alarm and an event are generated. If the check fails, a frozen failure problematic context is generated. The processing continues if the outcome is true or false.

  The Frozen Check is performed in a manner similar to the Daily vs. Aggregation Check. For more information, refer to Configure the daily vs. aggregations check.