6. Configuration and calibration
The following sections describe how to configure the refractometer and calibrate
concentration measurement.
6.1 Configuring refractometer
In PR-43, all parameter changes are made with a web browser through the
Parameters
page,
see
.
6.1.1 Signal damping
The system provides the possibility to enter signal damping to diminish the influence of
process noise. The damping is applied to the CONC value (and thus the output signal).
The PR-43 offers the following types of signal damping:
•
Exponential (standard) damping
works for most processes and is the standard choice for
slow and continuous processes.
• If the process has fast step changes,
linear (fast) damping
gives shorter settling time.
•
Slew rate
damping limits the maximum change for the output signal in one second.
The damping time is set separately. What the damping time means in practice, depends on the
damping type:
In
exponential damping
, the damping time is the time it takes for the concentration
measurement to reach half of its final value at a step change. For example, if the concentration
changes from 50 % to 60 % and damping time is 10 s, it takes 10 seconds for the refractometer
to display concentration 55 %. A damping time of 5
‑
15 seconds seems to work best in most
cases.
In
linear damping
(fast damping), the output is the average of the signal during damping time.
After a step change the signal rises linearly and reaches the final value after the damping time.
The figures below show how the damping time affects the measurement.
The
slew rate
parameter is presented in output units. For example when the concentration is
measured in percentages, typical slew rate value is 0.05 % to 1 %. It should be noted that the
slew rate limit damping is recommended for random noise suppression as it is non-linear.
The factory setting for damping in PR-43 is
5 s linear
. Avoid overdamping, the
signal should not be made insensitive.
The following figures show the effect of damping time on measurement.
PR-43 Series User Guide
M212455EN-B
24
Summary of Contents for K-PATENTS PR-43
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