5. COMMUNICATION IDENTIFIERS
IMSRM04-E8
68
Control loop break alarm (LBA) function
The LBA function detects the abnormality in the control loop such as the break of load (heater), the
abnormality of external operating unit (magnet relay etc.), the break of input (sensors), etc.
When the output reaches 100 % or 0 % (or output limiter low limit) the LBA function starts to
monitor periodically the change of measured value (PV) at previously set time and detects the break
of heater and input. For the TIO-K module (Position proportioning control), LBA functions with the
opening value set to output.
(1) LBA alarm condition
For heat control
When output becomes less than 0 %
(or output limiter low limit)
When output becomes more than
100 % (or output limiter high limit)
For
reverse
action
When measured value (PV) does not fall
below the variation width determined by
the LBA within the LBA set time.
When measured value (PV) does not rise
beyond the variation width determined by
the LBA within the LBA set time.
For
direct
action
When measured value (PV) does not rise
beyond the variation width determined by
the LBA within the LBA set time.
When measured value (PV) does not fall
below the variation width determined by
the LBA within the LBA set time.
The variation width determined by the LBA : Fixed 2
°
C (
°
F)
For heat/cool control
When the output on the heat-side
becomes more than 100 % (or output
limiter high limit) and the output on the
cool-side becomes less than 0 %
When the output on the heat-side
becomes less than 0 % and the output
on the cool-side becomes more than
100 % (or output limiter low limit)
For
heat/cool
control
When measured value (PV) does not rise
beyond the variation width deter-mined by
the LBA within the LBA set time.
When measured value (PV) does not fall
below the variation width determined by
the LBA within the LBA set time.
The variation width determined by the LBA : Fixed 2
°
C (
°
F)
When autotuning is used, the LBA set time which is twice the integral time thus set is
automatically set. (No LBA set time changes even if the integrated value is changed.)
