14
Proportional coefficient of PID (Kp 1):
Integral time of PID (Ti 1):
Differential time of PID (Td 1):
The proportional coefficient
Kp
is the controller amplifi-
cation and determines how strongly the control deviation
(the difference between the target temperature and ac-
tual temperature) directly affects the control variable (on-
time of the heater)�
Kp
values that are too large can lead
to the controller overshooting�
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 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�
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 small can lead to instability of the controller�
•
External and internal temperature control (ET)
(heating):
ET 0:
internal temperature control
ET 1:
external temperature control
If the external temperature control (
ET 1
) is selected, the
following items
EuT 2
(sampling time),
Kp 2
,
Ti 2
,
Td 2
,
Df t
(maximum temperature difference between internal
and external temperature) and
FAST
could be set� Other-
wise they are not displayed in the menu list�
The sampling time
EuT 2
(s) is the interval over which
the external control deviation and the respective control
variable (dependent on
Kp 2
,
Ti 2
,
Td 2
,
Df t
and
FAST
)
is determined�
EuT 2
must be adjusted to match the response charac-
teristic (total of all time constants) of the external closed
loop controlled system, so that the control variable can
deliver a uniform and measurable change in the control
deviation�
EuT 2
values that are too small or too large
can lead to instability of the controller�
Dynamics of the external PID temperature control (
FAST
):
FAST=0:
accurate, without overshoot
FAST=1:
fast, with overshoot
•
Alarm and key tone (BEEP):
BEEP 0:
no alarm and key tone
BEEP 1:
alarm and key tone is activated
•
Calibration and adjustment (CALI):
CALI 0:
Reset calibration
CALI 2:
2-point calibration
CALI 3:
3-point calibration
Example: 2-point calibration:
Dip the temperature sensor of the reference measuring
device into the bath fluid:
- If
ET 0
: into the internal bath (open the lid (2))
- If
ET 1
: at the same position as the external Pt100
temperature sensor (13)�
If
ET 0
: adjustment of the internal temperature measure-
ment�
If
ET 1
: adjustment of the external temperature measure-
ment�
Set the first point temperature (e�g� 80 °C)� Confirm the
setting by pressing the right knob (J)�
Left area of the display appears the set value (80 °C) and
the right area of the display appears the actual tempera-
ture value measured� The “Set” LED (B) flashes briefly�
Select 2-point calibration in the menu� Press the right
knob (J) to start the 2-point calibration�
•
Cooling (COOL):
0:
Cooling function is deactivated�
1:
Cooling function is activated�
