Alarm process
Normal
No
Yes
Alarm
condition
still?
Yes
No
Alarm
condition
Inhibit?
Yes
No
Delay timer
expired?
No
Yes
Disabled
alarm?
Alarm
handling
The controller detects an Alarm condition.
Check whether the alarm is disabled.
Check whether the alarm has an active inhibit.
Check whether the Alarm condition is still present.
The alarm is not activated until the delay timer has
expired.
Check whether the Alarm condition is still present.
The alarm is activated and included in the alarm list.
When an alarm condition is met (typically, the operating value reaches the Set point), then the controller starts the Time delay.
During this period the controller checks whether the Alarm condition is still present. If not, the alarm returns to normal.
• If the Alarm condition continues after the Time delay has expired:
◦ The alarm becomes active in the system.
◦ The alarm requires action and acknowledgement.
• If the Alarm condition clears after the Time delay has expired:
◦ The associated alarm does not become active, unless a Latch is present on the alarm.
◦ The alarm requires acknowledgement.
The alarm results in both a visual and audible (if a horn is correctly installed) indication (subject to design of the system) for the
operator. The system controls the alarm states as necessary based upon the operational conditions. Some alarms can be
configured to be automatically acknowledged.
INFO
Auto acknowledge can be useful during commissioning and troubleshooting. However, DEIF does not recommend Auto
acknowledge during normal operation.
During operation the system continues to monitor the Alarm condition(s) and moves alarms between different states as necessary.
Operator action can also move the alarm(s) to other states.
DESIGNER'S HANDBOOK 4189340911K UK Page 91 of 521
To Next Page
Loading...
