Alarms terminology

The following is a list of commonly used terms related to Alarms in PME.

Alarm

The term Alarm is commonly used to describe both, an alarm definition and an alarm instance. Which one it represents in an application must be derived from the context in which it is used. It is better to use the terms alarm definition and alarm instance to avoid ambiguity.

Alarm definition

An alarm definition is the specification of a defined condition for a particular measurement from a particular source. When the condition is met, the alarm goes active. When the condition is no longer met, the alarm goes inactive. Example: An Overcurrent alarm that goes active when the measured current for a load goes above a defined limit. The alarm definition includes the alarm name, the source and measurement, the alarm limits, and any other conditions that are relevant for the alarm.

Alarm instance

An alarm instance is a record of an occurrence where a monitored load exceeds the limits set in the alarm definition. An alarm instance starts when the alarm state goes active and ends when it goes inactive. An alarm Instance has a start and end date.

Alarm occurrence count

The alarm occurrence count is the number of alarm instances that have happened for an alarm definition.

Alarm state

The alarm state shows if the monitored load presently meets the conditions defined in the alarm definition or not. If it meets the conditions, the alarm state is Active. If it does not meet the conditions, the alarm state is Inactive.

Alarm acknowledgment

An alarm acknowledgment is a way to indicate in the software that you have seen the alarm and that it is being managed. When you acknowledge an alarm, the date and time of the acknowledgment is recorded together with an optional note that you can enter in the acknowledge window.

An alarm can be acknowledged after it has gone active. An alarm stays unacknowledged until you acknowledge it. After you have acknowledged an alarm, it stays acknowledged until the next time it goes active. At that point it is reset to unacknowledged and is waiting for you to acknowledge it again.

NOTE: You can acknowledge alarms in status views and history views. If you acknowledge alarms through an incident history view, all alarms that are part of this Incident will be acknowledged. Whenever you acknowledge an alarm, from any of these locations, you are acknowledging the alarm definition, not an instance of it. That means acknowledging an alarm marks it as acknowledged for all instances and resets the unacknowledged occurrence counter.

Incident

An incident combines alarms, waveforms, and burst data from many sources in the system. The elements are combined based on the proximity in time when the data was recorded and based on an analysis of the type of data. The goal is to create a single representation of a real-world power event that shows the impact of this event on the power system as a whole.

Representative power quality details (representative disturbance)

The representative power quality details describe the representative disturbance for an alarm or incident. The representative disturbance is used to categorize and quantify the alarm or incident. For an alarm the representative disturbance is the one that triggered the alarm. For an incident, which can include multiple alarms, the representative disturbance is the one with the highest severity in the incident. The representative power quality details include the source, type, direction, maximum abnormality, start time, end time, and duration of the disturbance.

Example representative power quality details:

  • Source: Campus.Residence Hall
  • Type: Sag
  • Disturbance Direction: Upstream - High Confidence
  • Maximum Abnorality: V3: 88.5%
  • Start Time: 2019-07-26 9:08:49.330 PM
  • End Time: 2019-07-26 9:08:49.530 PM
  • Duration: 200.0 ms

Representative waveform

The representative waveform is the waveform that is related to the representative disturbance for an alarm or an incident. If multiple waveforms are associated with the representative disturbance, then the representative waveform is selected based on the following priorities:

  1. The waveform covers full disturbance
  2. The waveform covers the start of the disturbance
  3. The waveform covers the end of the disturbance
  4. The waveform is inside the disturbance

Burst data

Burst data is pre- and post-event data that is logged during an alarm instance. The recording of the data is triggered by an alarm going active. Devices that support burst data keep a continuous buffer of data logs in memory, until a burst data capture is triggered. At that point, the data is recorded and uploaded to the software, together with the trigger time. By showing both pre- and post-event data, burst data is a very effective analysis tool. Burst data can be high speed data, such as half-cycle RMS measurements of voltages, currents, and other quantities, or it can be 1 second measurements for slowly changing parameters.

Event

Events are records of activity or conditions in the monitoring system. Events are generated by devices and the software and are logged and displayed as they happen in the system without any processing or aggregation. The system uses event records to determine alarm types and states.

Status view

A status view in the Alarms application shows alarm definitions in the system, their present state, how often they occurred, their priority, and other relevant information.

History view

A history view in the Alarms application shows instances of incidents, alarms, or events that have occurred in the system.