JUMO AQUIS 500 CR, Руководство по эксплуатации

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11 Appendix
86
Detection of deposits
Deposit detection can be activated for 4-electrode cells.
During normal operation, it can happen that deposits form on electrodes. This
has the result that a lower concentration is displayed than actually present.
When the “deposit detection” function is activated, the device tells you when
the cell needs to be serviced.
Autorange
The availability of two measuring ranges can be advantageous for some
processes – rinsing or regeneration processes, for instance.
What is usually required here, is the precise acquisition of a low conductivity.
Rinsing/regeneration, however, involves a much higher conductivity, which
could lead to an out-of-range condition (error). This situation is not just
unsatisfactory, but may even be dangerous. Thanks to the autorange function,
two measuring ranges can be determined. The device then switches between
them in a defined manner.
Pulse width controller (output is active for X > W and a P control structure)
If the process value X exceeds the setpoint W, the P controller will control
proportionally to the control deviation. On going outside the proportional
band, the controller operates with an output level of 100% (100% duty cycle).
Autorange can only be configured for the units mS/cm and µS/cm.
Range 1 must be smaller than range 2.
The controlling is only performed in range 1.
The process value output for range 2 is scaled to the full display span.
The changeover from range 1 to range 2 occurs when range 1 is exceeded.
The change back takes place when the process value goes below 90% of
range 1.
The change between the ranges can be signaled through the relay contact.
Process value X
Setpoint W
Proportional band X
P
100%
50%
0%
Output level y
Switching period
10%
90%
90%
10%
t
On
50% 50%
t
Off
10%
90%
X
P
X - W
0 1