7. FUNCTIONS
IMSRM02-E6
88
(7) Loop break alarm (LBA)
The loop break alarm (LBA) function is used to detect a load (heater) break or a failure in the external
actuator (magnet relay, etc.), or a failure in the control loop caused by an input (sensor) break.
This function monitors the measured value (PV) variation at LBA setting time intervals from the time
the output exceeds 100 % (or output limiter: high limit) or falls below 0 % (or output limiter: low
limit), then detects a heater or input break.
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Alarm action
The LBA function produces the alarm when any of the following causes occurs.
Heat control (LBA triggering width: 2
°°°°
C [
°°°°
F] fixed)
z
z
z
z
When the output falls below 0 % (or output limiter: low limit)
For direct action: This alarm is produced when the measured value (PV) does not rise beyond the
LBA triggering width within the LBA setting time.
For reverse action: This alarm is produced when the measured value (PV) does not fall below the
LBA triggering width within the LBA setting time.
z
z
z
z
When the output exceeds 100 % (or output limiter: high limit)
For direct action: This alarm is produced when the measured value (PV) does not fall below the
LBA triggering width within the LBA setting time.
For reverse action: This alarm is produced when the measured value (PV) does not rise beyond the
LBA triggering width within the LBA setting time.
Heat/cool control (LBA triggering width: 2
°°°°
C [
°°°°
F] fixed)
z
z
z
z
When the heat-side output exceeds 100 % (or output limiter: high limit) and the cool-side
output falls below 0 %
This alarm is produced when the measured value (PV) does not rise beyond the LBA triggering
width within the LBA setting time.
z
z
z
z
When the heat-side output falls below 0 % and the cool-side output exceeds 100 % (or output
limiter: low-limit)
This alarm is produced when the measured value (PV) does not rise beyond the LBA triggering
width within the LBA setting time.
If the autotuning function is used, the LBA setting time twice as large as the integral time is
automatically set. The LBA setting time does not change even if the integral time is
changed.
