Operation and Configuration
akYtec GmbH · Vahrenwalder Str. 269 A · 30179 Hannover · Germany Tel.: +49 (0) 511 16 59 672-0 · www.akytec.de
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6.14.2
Loop Break Alarm
The control loop break occurs and Loop Break Alarm (LBA) is activated, if the maximum
or minimum output signal is generated, but the process value remains unchanged within
the specified time. Once LBA has been activated, the control process will be stopped, the
alarm output activated and the
LBA
indicator flashes on.
The function is defined by two parameters in
Adv
group (see Fig. 6.12):
LbA
– LBA Time
LbAb
– LBA Range
Point A – the heater fails and the temperature goes down (Fig. 6.12
а), the output
signal
increases and the deviation grows (Fig. 6.12b)
Point B – the temperature keeps going down and the output signal reaches 100%, LBA
Time countdown begins
Curve I – if the LBA Time is exceeded and the temperature keeps going down, the alarm
is activated (Fig. 6.12c)
Curve II – if the process value starts growing, but the variation does not reach the LBA
Range within the LBA Time, the alarm is activated as well (Fig. 6.12c)
Fig 6.12
LBA Time is measured in seconds and can be determined as follows:
–
set the output signal to maximum
–
measure the time it takes the process value to change by the LBA Range value (10
by default)
–
double the measured value and set the result as the LBA Time
If
LbA
= 0, the LBA function is deactivated and
LbAb
not available.
LBA Range should be set in measuring units within the range 0.0…999.9 for the tempera-
ture sensors (RTD or TC) and within the range 0…9999 for the linear signals.
6.14.3
Safe state
In case of an error or LBA the control will be stopped and
–
in case of the on-off control Output 1 will be set to the level specified in the parameter
onEr
(On-off safe state)
