Setting Analog Alarm Limits

The following section describes various procedures regarding analog alarm limits.

Selecting Limit Sets

This procedure is used to activate a set of alarm limits for a group of analogs:

  1. Call up the Limit Replacement and Restoration display.

Click the radio button for the desired limit set.

The button toggles to the “Selected” state; the previously selected limit set toggles to “Unselected”. All analogs using the selected limit set have their alarm limits replaced with the selected limit set. Analogs that have been individually overridden do not have their limits replaced.

Overriding Analog Alarm Limits

The following procedure describes how to override replacement alarm limits for an analog. When a limit is overridden, the analog is no longer a candidate for limit replacement by the limit set activation function, if the analog is part of a limit set.

  1. Call up the Substation Tabular display containing the desired analog limit.

Select the limit field to be overridden.

The field becomes enterable.

Type in a new value, and press Enter.

If you have permission to replace the limit, the new value is accepted and a Restore Limit button appears, accompanying the device for which the limit was overridden. If the limit override is rejected, the field turns red and a message explains the reason for the rejection1.

Removing a Limit Override

This procedure describes how to remove the operator override of an analog alarm limit:

  1. Call up the Substation Tabular display containing the analog for which you want to remove the overridden limit.

Click the Restore Limit button accompanying the device for which the analog limit was overridden.

If you have permission to do so, the override is removed. The Restore Limit button disappears, and the limit is replaced by the currently active default limit set value, if the analog is part of a limit set.

Removing Limit Overrides by Type

This procedure describes how to remove all operator overrides on analog limits for a given type of analog:

  1. Call up the Limit Replacement and Restoration display, and click the Limit Restoration by Analog Name radio button.

The Limit Restoration by Analog Name view appears.

Click the Restore Default Limits button for the desired analog.

If you have permission to do so, the override is removed, and the limit is replaced by the currently active default limit set value, if the analog is part of a limit set.

Disabling Alternate Limit Replacement

This procedure describes how to disable or enable alternate limit set replacement of a selected Alternate Limit Type:

  1. Call up the Limit Replacement and Restoration display.

Click the Disabled button.

This is a toggle operation. If the button is toggled ON, automatic limit replacement of any of the Alternate Limit Sets for this Alternate Limit Type is disabled. If the button is toggled OFF, automatic limit replacement is enabled. The actual replacement may not be affected until either the trigger analog is re-evaluated (once a minute) or until the configured date/time, depending on the modeling of these records.

1. A limit value might be rejected because:It is improperly nested with its higher or lower limit.It is outside of the analog’s reasonability limits.You attempted to modify a null limit or enter a null limit. A null limit is one whose value appears as blanks on the display.The new range between limits is smaller than the deadband for the limit. This only applies for limits that have an absolute deadband rather than a percentage deadband. ↩