If the proportional range selected is too small, the P part on the control
value is at 100 % for a very long time. This value then reduces more
quickly within the proportional range, i.e. the control value reduces rapidly
and the approach of the actual value to the setpoint almost comes to a
standstill. Due to the I part not becoming effective until now, the actual value
approaches the setpoint slowly.
In this case shown, the I part is set too large (parameter Tn too small). The I
part integrates the control deviation until this becomes 0. If this integration
runs too quickly, the control value, i.e. the output signal of the controller, is
too large. This results in (diminishing) oscillations of the actual value around
the setpoint. Parameter Tv should be adjusted again using the formula:
Tv = Tn x 0.75.
The actual value increases relatively steeply after specification of the set-
point. The proportional range appears to be well-adjusted. The approach to
the setpoint becomes significantly slower for diminishing control deviation.
The strong reduction of the proportional part (P part) must be compensated
for by the integration part (I part). In this case, the I part integrates too
slowly. The parameter Tn which specifies the integration interval must be
reduced. The lead time (parameter Tv) should also be adjusted using the
following formula: Tv = Tn x 0.75.
6.11.2
Opening the control menu
Personnel:
n
Operating personnel
1.
Change to the main menu.
2.
Select the menu item
Setup
Control
.
Fig. 34: Control parameter Xp too small
Fig. 35: Control parameters Tn and Tv too
small
Fig. 36: Control parameters Tn and Tv too
large
V08
Variocool
49 / 97
Summary of Contents for VC 1200
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