K-Patents PR-21-S - Manual (Page 50)

44 PR-21-S instruction manual
6.1.2 Linear damping
If the process has fast step changes, linear (fast) damping gives shorter settling
time. In the linear damping (fast damping), the output is the running average of
the signal during the damping time. After a step change the signal rises linearly
and reaches the final value after the damping time. The linear damping gives the
best trade-off between random noise suppression and step change response time.
Use the
4 DAMPING TIME menu item to set the damping time. Please note that for
similar noise suppression a longer damping time has to be specified than for the
exponential damping.
Figure 6.2 shows how linear damping time affects the measurement.
0 10 20 30 40 50 60 70 80 90 100 110 120
Time [s]
12.0
12.1
12.2
12.3
12.4
12.5
12.6
12.7
12.8
12.9
13.0
CONC [%]
7 s
15 s
30 s
Figure 6.2 Linear damping
6.1.3 Slew rate limit
If the process signal has short erroneous high or low peaks, the slew rate limiting
can be used to cut their effects. The slew rate damping limits the maximum change
for the output signal in one second. It should be noted that the slew rate limit
damping is recommended for random noise suppression as it is non-linear.
The slew rate limit can be set through the menu item 5 SLEW RATE . Typical values
depend on the concentration unit but are typically from 0.05 % to 1 % when the
concentration is measured in percentages. Figure 6.3 gives an example of different
slew rate limits.
Note: Avoid overdamping, the signal should not be made insensitive.
6.2 Configuring output signal hold functionality
The instrument can be configured to temporarily hold its measurement result in
three different cases.
1. By using an external hold switch (see Section 6.4)
2. During prism wash (see Section 6.7.2)
3. For a preprogrammed time when there is an intermittent loss of sample on the
prism (due to voids in the process)