Lauda RP 890 - External Control Variable (External Measurement Probe)

Proline Low-temperature Thermostats
88 Starting up YACE0072 / 21.08.07
7.13.1.1 Proven settings for control parameters and pump (integral measurement probe)
Instrument
Type
Heat carrier Liquid
Xp
^O
Tn
rl
Tv
rs
Td
rc
Pump Level
RP 845 Water 4.0 50 35 6 4
RP 845 Ethanol 7.0 50 35 6 4
RP 845 Ethanol 5.5 30 21 3.6 4
RP 855 Ethanol 7.0 50 35 6 4
RP 855 Ethanol 7.0 30 --- --- 4
RP 855 Water 4.0 30 --- --- 4
RP 855 Water-Glycol 4.0 30 --- --- 4
RP 1845 Ethanol 5.5 50 40 6 5
Technical changes reserved!
7.13.2 External control variable (External measurement probe)
You only need to read further here if you have connected an external temperature probe or the actual
temperature is read in from a module (and you have activated it as control variable according to Section
7.7.4).
Only modify the co
ntrol parameters if you have knowledge of control techni
ques.
The control system for external actual values is implemented for improvement of the control behavior as
a two-stage cascade controller. A "master controller" determines the "internal setpoint", from the
temperature setpoint and the external temperature, passed to the slave controller. The control value of
the slave controller controls the heating and cooling.
When a setpoint step change is specified, it may be that the optimum control would set a bath
temperature, which might significantly exceed the temperature desired on the external vessel. There is
a correction limitation, which specifies the maximum permissible deviation between the temperature on
the external load and the heat carrier liquid temperature.
Master
O0c--
3x to LMDls
1x
to O0c--
− As shown in the menu structure (Ì 7.6.6 ), the parameters for the
external control variable can now be set.
− Select the parameter with
or and confirm with . The set
value is displayed. Adapt it with
or confirm with .
− Example: Proportional factor of the master controller Kpe = 1.5.
Parameters Master controller (PIDT
1
-controller):
− Ma proportional factor: DO = Kpe as factor.
− Ma proportional range: Da = Prop_E in kelvin.
− Ma reset time: Dl = Tne in seconds.
− Ma derivative time (auto/man) Dt = Tve in seconds.
The thermostat logic system only permits values with Tne > Tve!
− Ma damping time (auto/man) Dc = Tde in seconds.
DO !4
°C