18
Menu (Details):
TEMPERING:
1� Control:
1) Control Mode:
Internal (int):
The temperature is regulated according to
the internal temperature sensor�
Extern (ext):
The temperature is regulated according to the
external temperature sensor�
2) Control parameters:
Automatic:
The optimal control parameters for PID tem-
perature control are determined automatically� This is the
recommended mode�
Selecting "Automatic" allows you to set the dynamics for
temperature control�
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:
3) Fluids:
Under the option "Fluids", a variety of fluids can be selected�
The selected fluid limits the setting range of the target
temperature� See table in the section “Fluids (Standard in-
formation for
IKA
fluid)“�
The maximum and minimum temperature values of the
selected fluid can be set within these limitations�
2� Limits:
Under the option "External (ext)", the maximum and minimum
temperature for external temperature control can be set�
Under "l Δ T (int - ext) l", the maximum difference be-
tween the internal and external temperature can be set�
The function limits the absolute temperature difference
between the external system and internal bath during the
heating up and cooling down process� This can protects
sensitive device like the glass reactors from thermal shock
(e�g� glass break)�
Kp too high
°C
t
Ti too high
°C
t
Kp too low
Ti too low
°C
t
Td too high
°C
t
Fig. 26
Manual:
The control parameters for PID temperature con-
trol 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 cooling)�
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�
Fig. 25
(cooling curve in “Automatic” mode)
°C
t