Lauda V1R20 Operation Manual page 31

Example of a program with tolerance
Fig. 25: Example of a program with a tem-
perature profile for a specified tolerance
Program optimization
V1
The edited profile (dotted line) is essentially achieved by splitting up the
previous segments 3:
3a (seg. 3 new): A maintain phase is added in front of segment 3 which

maintains the temperature of 50 °C reached with the first ramp for
20 min. The segment numbers of the following segments increase by
one counter.
3b (seg. 4 new): The time limit for the previous segment 3 has been

halved, the increase of the second ramp now corresponds to that of
the first ramp. In this way, the total duration of the program sequence
remains unchanged.
Specifying a tolerance ensures strict compliance with the retention time at
a specific temperature, for example. The effect of specified tolerances is
shown here for the edited profile of the previous example of a program. To
this end, the following additional tolerances were entered for the start of the
temperature maintenance phases:
Seg. 1 - Tolerance = 0.1 °C
Seg. 3 new (3a) - Tolerance = 0.1 °C
Seg. 5 new (4) - Tolerance = 0.8 °C
In the graph opposite, the programmer's target setting is shown as a gray
area, the curve shows the delay caused by the tolerances. Note the following
information about the marked points:
(1): Each temperature change indicates a transient response when the

target temperature is reached. Its duration depends on the steepness of
the previous ramp resulting from the ratio between the duration of the
segment and the difference in temperature.
(2): A specified tolerance is only achieved when the target temperature

remains within the tolerance range. This causes the next segment to
have a delayed start.
(3): A generous tolerance range has been set here with 0.8 °C.

Despite a steep ramp, this causes manageable delays. The time limit
of 10 minutes can also be maintained with transient processes.
(4): For this ramp, a narrow tolerance range was selected with 0.1 °C.

Severe delays can be the result, in the worst case, the next program
sequence is prevented. This is especially true in conjunction with external
control and for steep ramps that are close to the maximum possible
heating rates or cooling rates of the constant temperature equipment.
If possible, only program tolerances for flat (slow) ramps or with an
appropriate tolerance range.
The purpose of program optimization is to improve a program's control action
and minimize overshooting. Programs that contain other segment types in
addition to ramps usually achieve a significantly better match between the
actual temperature curve and the target temperature curve when program
optimization is activated.
There can only be increased undershooting at the ramp ends if the control
parameters are very unfavorable. In this case, you should deactivate program
optimization.
Command Touch operating unit 31 / 51