Menu (Details) - IKA IC control Operating Instructions Manual

• Menu (Details):

TEMPERING:
1� Control:
1) Control Mode:
Internal (int):
The temperature is regulated according to the internal
temperature sensor (Fig� 2 Item 6)�
Extern (ext):
The temperature is regulated according to the external
temperature sensor (Fig� 2 Item 11)�
2) Control parameters:
Automatic:
The optimal control parameters for PID temperature con-
trol are determined automatically� This is the recommend-
ed mode�
Selecting "Automatic" allows you to set the dynamics for
temperature control:
Accurate: precise tempering without overshooting�
Fast: fast tempering with minimal overshooting�
°C
Fig. 26 (heating curve in "Automatic" mode)
Manual:
The control parameters for PID temperature control can be
set manually�
"Manual" should only be used in the event of special tem-
perature control requirements�
When "Manual" is selected, the following parameters can be
set for "Internal (int)" and "External (ext)" temperature control:
Kp: Proportional coefficient
The proportional coefficient Kp is the controller amplifica-
tion and determines how strongly the control deviation
(the difference between the target temperature and actual
temperature) directly affects the control variable (on-time
of the heater)� Kp-values that are too large can lead to the
controller overshooting�
Ti: Integral time
The integral time Ti (s) is the correction time and deter-
mines how strongly the duration of the control deviation
affects the control variable� Ti compensates for an existing
control deviation� A high Ti means a smaller and slower
effect on the control variable� Ti-values that are too small
can lead to instability of the controller�
Td: Differential time
The differential time Td (s) is the derivative time and de-
termines how strongly the rate of change of the control
deviation affects the control variable� Td compensates for
rapid control deviations� A high Td means a smaller and
slower effect on the control variable� Td-values that are
too large can lead to instability of the controller�
Ts: Sampling time
The sampling time Ts (s) is the time interval over which the
control deviation is determined and the respective control
variable (dependent on Kp, Ti and Td) is calculated�
Ts must be adjusted to match the response characteristic
(total of all time constants) of the closed loop controlled
system, so that the control variable can deliver a uniform
and measurable change in the control deviation� Ts values
that are too small or too large can lead to instability of the
controller�
Prop_Bp: Proportional Band Maximum�
Prop_Bn: Proportional Band Minimum�
The Proportional Band is the range below (Prop_Bp) and
above (Prop_Bn) the set value in which the control output
value is calculated via the difference between the actual
and the set value and the PID parameters�
Examples of non-optimal settings:
°C
°C
t
°C
°C
Fig. 27
3) Fluids:
Under the option "Fluids", a variety of heat transfer fluids
can be selected�
The selected fluid limits the setting range of the target
temperature� See table in the section "Fluids"�
The maximum and minimum temperature values of the se-
lected fluid can be set within these limitations�
Kp too high
t
Ti too low
t
Kp too low
Ti too high
t
Td too high
t
18