Enable and configure tank alarms

Level Alarming

Deadband

In the Deadband field, enter the tank volume deadband. If a tank enters an alarm state, AVEVA Enterprise SCADA will not consider it as having returned to a normal state until the volume changes by an amount equal to, or greater than, the deadband value. The deadband value prevents alarms from being generated due to minor fluctuations in volume.

HiHi Alarming Limit

Hi Alarming Limit

Lo Alarming Limit

Normal Fill

Normal Empty

LoLo Alarming Limit

Select the checkbox to generate an alarm when the tank level meets or exceeds the Normal Fill, Hi, or HiHi limit, or meets or falls below the Normal Empty, Lo, or LoLo limits.

To set any of these six limits:

1. Ensure that the checkbox is selected.

2. Enter the limit in the fields next to the desired limit.

3. To change the alarm limits, select Submit.

   Note: All enabled alarms in this group should be arranged so that HiHi > Hi > Normal Fill > Normal Empty > Lo > LoLo.

User Configured Alarms

Hi Alarming Limit

Lo Alarming Limit

Setting your configured Hi and Lo Limits:

4. Ensure that the checkbox is selected.

5. In the Hi and Lo fields, enter the limits.

6. To change the Hi and Lo alarm limits, select Submit.

   User-configured alarms should be arranged so that User Hi is larger than User Lo. They are distinct from the Level Alarming alarm limits.

Instrument Fail

Enable

AVEVA Enterprise SCADA declares an instrument/transducer fail high or fail low alarm when the input value at the Remote Terminal Unit (RTU) is outside of the field instrument’s measurable range. Return-to-Normal is declared as soon as the input value returns within the range of the instrument/transducer fail Hi and Lo alarm limits.

Instrument/transducer failure alarms take precedence over HIGH-HIGH/LOW-LOW alarms, HIGH/LOW alarms, and Normal Fill and Normal Empty alarms. However, if your Administrator has enabled the attribute-based instrument failure alarm functionality (that is, by using the INSTR_FAIL_AS_ATTRIBUTE setting), the alarm can co-exist with a state-based HIGH/LOW alarm (HIGH-HIGH, LOW-LOW, and so on).

These are RTU-specific alarms and may not be supported in some systems.

• Select Enable to enable Instrument Fail alarming.

Rate of Change Alarming

Enabled

To enable Rate of Change Alarming, select Enabled.

Filling ROC Limit (Units/Hr)

Enter a filling Rate of Change (ROC) value greater than zero. If the tank flow rate exceeds this limit, the tank will then be in an ROC Alarm state—this state may result in a non-persistent alarm if not inhibited.

Emptying ROC Limit (Units/Hr)

Enter the emptying ROC value greater than zero. If the tank flow rate exceeds this limit, the tank will then be in an ROC Alarm state—this state may result in a non-persistent alarm if not inhibited.

Realarming

Time (min)

The Re-Alarming application re-annunciates critical and high priority alarms after a configurable amount of time if the condition that caused the alarm still exists.

• In the Realarming Time(Min) field, enter the number of minutes after which an acknowledged alarm should re-alarm.

Creep Alarming for Idle Tank

Enable Creep Alarming

To configure AVEVA Pipeline Operations for Liquids to generate a deviation alarm on an idle tank, select Enable Creep Alarming. The tank can be configured with a creep Deviation Type that determines whether creep detection is based on level or volume thresholds. For each type, positive and negative thresholds can be specified. Only one Deviation Type can be enabled for the tank.

When a tank is marked as idle, the current level and volume are saved. If the selected Deviation Type is Level and the current level in the tank differs from the saved level by more than the configured thresholds, AVEVA Pipeline Operations for Liquids generates a deviation alarm and the new level is saved. This new level now becomes the reference level for future deviation alarms. If the selected Deviation Type is Volume and the current volume in the tank differs from the saved volume by more than the configured thresholds, AVEVA Pipeline Operations for Liquids generates a deviation alarm and the new volume is saved. This new volume then becomes the reference volume for future deviation alarms.

To set the Creep deviations:

7. Select the Enable Creep Alarming checkbox.

8. Select the Deviation Type from the dropdown.

9. In the corresponding + Deviation field, enter the deviation threshold.

10. In the - Deviation field, enter the deviation threshold (using a positive numeric).

11. To save these changes, select Submit.