21
Controlling the Medium temperature limit via ETS-D or Contact Thermometer
The preferable method for controlling the average temperature is
with the ETS-D or contact thermometer. After the set point tempera-
ture has been adjusted, this results in a short heating-up time, practi-
cally no temperature drift and only minor fluctuation in temperature.
In addition to precise control function, the adjustable ”MAX-
TEMP” function makes the ETS-D a temperature limiter that
has a direct effect on the average temperature. When this
“MAXTEMP” is exceeded, for example because of a defect in
the control circuit or unintentional of the “Safe Temp” or set
point temperature on the RCT, the ETS-D immediately and
permanently turns off the separate circuit of the RCT.
The stirring function then continues to run at the speed that was set
before the malfunction.
A 6-pin jack is located on the rear side of the instrument for connec-
ting the ETS-D, the contact thermometer or the contact plug. The
electronics of the instruments returns a test current that must flow via
connector pins 3 and 5 for the heating plate to heat up.
Safety contact thermometers
acc. to DIN 12 878 class 2 or acc. Gerstel are connected with a three
wire cable, the test current flows through the contact thermometer.
Safety function:
If the test current is interrupted because of e.g. breakage of contact
thermometer or falling out of the cable plug, the heating cuts off.
The required plug allocation is indicated on a reference plate above
the diode bushing.
Contact thermometer without safety circuit
acc. to DIN 12 878 class 0. The instrument only heats if the test
current circuit is closed by an electrical connection of the plug pins
3 and 5.
2-wire connecting cables:
Connect plug pins 3 and 5 of the instrument plug.
3-wire connecting cables:
Here the test current circuit can also be produced in the terminal
head of the contact thermometer (connect plug pins 2 and 3).
A 3-wire cable with the required bridge is available (accessories).
Settings
For the detailed instructions for settings and limit values, please
refer to the operating instructions for the instrument you are con-
necting.
The desired average temperature can be adjusted on the
ETS-D or contact thermometer. In addition, a “MAXTEMP”
can be set for the ETS-D, in other words, a maximum ave-
rage temperature can be set for malfunctions in combina-
tion with the RCT. The required surface temperature of the
heating plate can be selected with the “Temp” dial.
Adjusting the “Temp” dial to the maximum adjustable temperature
will result in the fastest possible heating time, but the average
temperature may fluctuate to values above the set-point tempe-
rature on the contact thermometer, for example. By adjusting the
“Temp” dial to approximately twice the set-point value (thus with
a set-point or 60 °C the Temp dial would be set to 120 °C), you
will reach a good compromise between a fast heating time and
overshooting the set point.
If you adjust the Temp dial to exactly the set-point temperature, the
medium will not reach the set-point temperature, since some loss of
the heat will always occur between the heating plate and the medium.
The maximum heating plate temperature can be adjusted
will the “Safe Temp” screw.
