Alarm Duration and UNACK Duration for LATCHED Alarms
- Last UpdatedFeb 07, 2023
- 2 minute read
This section describes the calculation of Alarm Duration and UNACK Duration for LATCHED state. Alarm Duration is the time duration between active alarm and inactive alarm. UNACK Duration is the time duration between UNACK Alarm and ACK Alarm. The Alarm Duration and UNACK Duration for the LATCHED state can be calculated in two ways:
Option 1: Alarm is acknowledged and then returned
|
Alarm State |
Denominated As |
Alarm Duration |
UNACK Duration |
|
UNACK |
Tt |
- |
- |
|
ACK |
Ta |
- |
Tf-Tt |
|
LATCHED |
Tf |
Tf-Tt |
Tf-Tt |
|
ACKRTN |
Td |
Tf-Tt |
- |
When the alarm is acknowledged, the UNACK Duration will be the time difference between ACK and LATCHED state, that is Ta-Tt. There will not be any Alarm Duration. When the alarm state is changed to LATCHED, then the Alarm Duration will be updated with the time difference of LATCHED and UNACK. that is Tf- Tt. The UNACK Duration remains same. When the LATCHED state is changed to ACKRTN, the Alarm Duration will be same, that is Tf-Tt and there will not be any UNACK Duration.
Option 2: Alarm is returned and then acknowledged
|
Alarm State |
Denominated As |
Alarm Duration |
UNACK Duration |
|
UNACK |
Tt |
- |
- |
|
UNACKRTN |
Tf |
Tf-Tt |
- |
|
LATCHED |
Ta |
Tf-Tt |
Tf-Tt |
|
ACKRTN |
Td |
- |
Tf-Tt |
When the alarm is returned, the Alarm Duration will be the time difference between UNACKRTN and UNACK, that is Tf-Tt. When the alarm state is changed to LATCHED, the alarm duration will be the same. The UNACK duration will be the time duration between LATCHED and UNACK, that is Ta-Tt. When the alarm changes to ACKRTN the UNACK Duration will be the same and there will not be any alarm duration.
The below image shows the timing diagram for both the options of Alarm Duration and UNACK Duration for LATCHED Alarms:
