Alarms / Alarm Trigger List
Introduction
Alarm triggers are the criteria which define when NovaStar activates an alarm and associated alarm actions in response to incoming data. This criterial is unique to each NovaStar installation. The development of appropriate alarm triggers requires judgment and may be altered in response to experience and to accommodate the requirements of emergency responders. The ideal alarm triggers do not create frequent nuisance alarms when circumstances do not warrant response, but also do not fail to provide notification when appropriate. Due to variations in the relationship between monitored data values and the outcomes of interest, it can be difficult to find the correct balance in alarm trigger criteria. For example, precipitation monitoring that strives to provide early warning of potential flooding relies on data reports of measured rainfall at monitored locations. The relationship between that data and actual flooding can be determined after the fact, but is the result of the combination of rainfall distribution (both in space and over time), antecedent ground conditions, rainfall intensity, and flood routing characteristics of the watershed. Not all of these variables have a simple relationship to the monitored data.
Multiple alarm triggers can be assigned to an alarm group. For example, typically an alarm group of precipitation data points are configured to provide alarm notification in the event of heavy rain, but also when data reports are not being received or polled on the expected schedule, etc.
Alarm Trigger List
A new NovaStar system contains an empty trigger list on the Alarm Trigger List page.
The Alarm Trigger List displays the alarm triggers currently defined in the NovaStar system and can show details about each trigger. The following image illustrates the Alarm Trigger page after selecting a trigger from the list.
Alarm Trigger Identification (see full-size image)
Navigation, Adding, Deleting, Modifying, and Copying Alarm Triggers
See Application Functionality for more information about basic component functionality.
The Alarm Trigger List page conforms to a layout similar to many data types which includes a list of data items. See List Features for more information detailing page navigation; adding, copying and deleting alarm triggers; and modifying existing alarm triggers.
Identification
The following properties are used to identify the alarm trigger.
Alarm Trigger Identification (see full-size image)
| Data Label | Description |
|---|---|
| Name | Alarm trigger name. Max: 100 characters. |
| Description | Enter additional information describing alarm trigger. Max: 1000 characters. |
User Groups
The User groups table shows the user groups currently assigned to the alarm trigger. For more information, see the User Groups documentation.
User Groups Assigned (see full-size image)
Limits
Alarm Trigger Limits (see full-size image)
| Data Label | Description |
|---|---|
| Type | Select alarm trigger type from pick list. Upper - Limit alarm activates when data meets or exceeds the upper limit value Lower - Limit alarm activates when data meets or falls below the lower limit value Rise - Alarm activates when data value rises by limit over period Fall - Alarm activates when data value falls by limit over period Norpt - Alarm activates when data does not report within period At - Alarm activates when a data value matches the value System - Alarm activates when NovaStar 5 detects a system failure. System alarms are not related to point report values. They are used by the NovaStar 5 system to alert when a data collection port or backup computer system problem is encountered. Rptcnt - Alarm activates when report count over period is met Export - |
| Limit | Numeric value at which an alarm will activate. |
| Interval | For rate-of-change alarm trigger types (rise or fall), the interval must also be entered. The alarm is activated when a new data report stored in the database changes by at least the alarm limit over the specified time period interval. No report (norpt) interval alarm trigger types only show the Interval field. |
| Reset | Numeric value at which an alarm will reset. A Reset value is entered to prevent minor fluctuations near the alarm limit from producing nuisance alarms for alarms using upper and lower limit criteria. An alarm remains active until the reset value is crossed by new data stored in the database. If the reset value is blank or equal to the limit, any value below the limit causes a reset. No report (norpt) interval alarm trigger types do not have reset values or intervals. The below image demonstrates the use of reset values.  Alarm Trigger Limit and Alarm Reset Logic (see also the full-size image) |
| Threshold | This value is entered for rate-of-change alarm trigger types (rise or fall). When a threshold is set, the new data value must meet or cross the threshold value before this alarm checking is done.  Alarm Trigger Rate of Change Threshold Logic for No Reset (see also the full-size image)  Alarm Trigger Rate of Change Threshold Logic for Rise Reset Interval |
| When | Direction threshold must be passed. none: no threshold used at or above: value must meet or rise above threshold. above: value must rise above threshold. at or below: value must meet or fall below threshold. below: value must fall below threshold. Rise and fall alarm checking does not compute rate of change from the last report to the new report. It checks the change in value over the time period. Rise and fall alarms must specify the period over which the change is checked. A greater change and longer interval acts as a filter to prevent smaller fluctuations from sounding alarms. The alarm is reset when the data value drops by the reset limit over the reset interval. If the reset is zero (0) or blank, any decrease in the data value will cause a reset. |
Actions
This section defines when the actions in the Action List are executed. These are internal-facing criteria. The Nova Score is only used within the NovaStar database and is not usually indicated in the outgoing information.
Alarm Trigger Actions (see full-size image)
| Data Label | Description |
|---|---|
| Nova Score | Select nova score from pick list to assign to data reports meeting alarm trigger criteria. A nova score can be assigned to an alarm trigger to help categorize the alarm trigger based upon a judgment about the relative severity of the data report values that trigger the alarm. The nova score value is stored with the data report value and can be used to highlight data values in reports and on maps. The higher the nova score value, the "hotter" the background color. See the Nova Score List section. |
| Hidden | Select true to prevent NovaStar from displaying this alarm and setting the alarm flag in the data report. This is useful when alarm triggers are used to set nova score values, control a map display LED, or export data. Displaying these alarms makes it time consuming to search for significant alarms. Hidden alarms can be displayed in the Alarm List by selecting the hidden alarm state detail. |
| When met | Select true to execute alarm actions when alarm criteria are met. |
| When reset | Select true to execute alarm actions when alarm criteria are reset. |
| Message | A message can be entered that will be included when alarm notifications occur as a result of the associated alarm trigger. Max: 1000 characters. |
Action List
The Action list displays the alarm actions currently associated with the alarm trigger and can show details about each alarm action.
Alarm Trigger Action List (see full-size image)
Clicking the Add button navigates to the Alarms / Alarm Action List page to allow creation of a new action. However, to assign or remove an existing action, click the Assign/Remove Actions tab above the action list to display the list of existing actions. Check or uncheck desired actions.
Alarm Trigger Action List Choices (see full-size image)
Alarm Trigger Test
The alarm trigger can be tested by triggering an alarm for the point selected. When the Test button is clicked, a test alarm is triggered and all actions associated with this trigger are executed. The word "TEST" is prepended to the alarm message.
Alarm Trigger Test (see full-size image)
| Point | Description |
|---|---|
| Point | Select the point for the alarm trigger test from the pick list. |