Lauda VC 1200, Руководство по эксплуатации

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Personnel:
n
Operating personnel
1. Select the menu item Offset value in the set point offset menu.

An entry window appears.
2. Adjust the offset value within the displayed limit values.
3. Press the input button to confirm.
6.11 Control
The internal and external control parameters are preset at the factory for
operation as circulation chiller (with water as heat transfer liquid). Depending
on the application, adjustments of the control parameters can be necessary
from case to case. The thermal capacity and the viscosity of the heat transfer
liquid also influence the control behaviour and may require adjustment of the
control parameters.
6.11.1 Basics
Control
value
- Output value of the controller to compensate for the difference
of actual value to setpoint (control deviation).
PID
con-
troller
- The PID controller operates very precisely and consists of P, I
and D parts.
Propor-
tional
range Xp
- The proportional range Xp specifies the temperature range
in which the proportional part (P part) of the controller is
0 – 100 % of the maximum control value. For example, if the
control deviation is 2 K for Xp set to 10 K, the P part is 20 % of
the control control deviation. In the case of a control deviation
of 10 K and more, the P part is 100 % of the control value.
Reset
time Tn
- The reset time is decisive for the integral part (I part) of the
control value. It specifies the interval in which an existing con-
trol deviation is integrated. The larger Tn is, the slower the
control deviation is integrated. Thus, the control is slower. A
smaller Tn makes the control more dynamic and finally results in
oscillations.
Lead
time Tv
- The differential part (D part) of the control value is formed from
the lead time Tv. It influences the approach speed of the actual
value to the setpoint and counteracts the P and I parts. The
larger the lead time Tv is set, the stronger the output signal is
damped. As rule of thumb, the following applies: Tv = Tn x 0.75.
An important prerequisite for acceptable control quality is a well designed
hydraulic system. Therefore, an as good as possible connection between
the application to be temperature-controlled and the constant temperature
equipment must be established. This means:
Specifying the offset
Fig. 31: Specifying the offset value
Explanation of terms
Optimising the hydraulic system
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