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4.3.1.1.4.5 Loop Break Alarm
A1FN selects LB if alarm 1 is required to act as a loop break alarm. Similarly, if alarm 2 is
required to act as a loop break alarm, then set OUT2 with=AL2 and A1FN with LB.
TIME, A1SP, A1DV and A1HY are hidden if alarm 1 is configured as a loop break alarm.
Similarly, TIME, A2SP, A2DV and A2HY are hidden if alarm 2 is configured as a loop break alarm.
One of 4 kinds of alarm modes can be selected for alarm 1 and alarm 2.
These are: Normal alarm, latching alarm, Holding alarm and Latching/Holding alarm. However, the
Holding mode and latching/Holding mode are not recommended to be chosen for loop break alarm
since loop break alarm will not perform holding function even if it is set with holding or
latching/holding mode.
Loop Break Conditions are detected during a time interval of 2TI1 (double of integral time,
but 120 seconds maximum). Hence the loop break alarm doesn't respond quickly as it occurs. If
the process value doesn't increase (or decrease) while the control variable MV1 has reached to its
maximum (or minimum) value within the detecting time interval, a loop break alarm (if configured)
will be actuated.
Loop Break Alarm (if configured) occurs when any following condition happens
Input sensor is disconnected (or broken).
Input sensor is shorted.
Input sensor is defective.
Input sensor is installed outside (isolated from) the process.
Controller fails (A-D converter damaged).
Heater ( or generally, chiller, valve, pump, motor etc. ) breaks or fails or uninstalled
Switching device (used to drive heater) is open or shorted.
4.3.1.1.4.6 Sensor Break Alarm
Alarm 1 or alarm 2 can be configured as sensor break alarm by selecting SENB for A1FN
or A2FN.The sensor break alarm is activated as soon as failure mode occurs. Note that A-D failure
also creates a sensor break alarm. TIME, A1SP, A1DV, and A1HY are hidden if alarm 1 is
configured as a sensor break alarm. Similarly, TIME, A2SP, A2DV and A2HY are hidden if alarm 2
is configured as a sensor break alarm.
One of 4 kinds of alarm modes can be selected for sensor break alarm. These are: Normal
alarm, latching alarm, Holding alarm and Latching/Holding alarm. However, the Holding alarm and
Latching/Holding alarm are not recommended to be chosen for sensor break alarm since sensor
break alarm will not perform holding function even if it is set with holding or latching/holding mode.
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