Setup mode
OPERATION MANUAL
Chapter 4
Unistat® T300 Series
V2.4.0en/22.07.20//17.12
56
4.2.3
Temperature control to process temperature
Certain temperature control tasks require that the temperature is recorded elsewhere for best
results than described. Setting the temperature to process temperature makes alternatives availa-
ble. When setting the temperature to process temperature, an additionally connected external
Pt100 temperature sensor is used in conjunction with a master controller (cascade controller). The
internal sensor at the supply line is integrated with the slave controller. This temperature control
method is used e. g. for the thermostatic control of jacket vessels. The setpoint setting is valid for
the process controller. It in turn calculates a target value for the internal controller to optimally
adjust the process setpoint.
Incorrect installation of the process sensor (Pt100)
MATERIAL DAMAGE CAUSED BY FAULTY TEMPERATURE CONTROL
Disruption of measured value recording due to static build-up.
The process sensor (Pt100) must have a screened supply cable.
If the sensor tube is metallic, take care to avoid ground loops.
The connection cable should not be unnecessarily long.
Make sure that the process sensor is properly attached at the measurement point and that
there is good thermal coupling
The sensor itself must have good insulation from the screen or the protective grounding (R > 20
MΩ).
4.2.4
Delta T limiter
The Delta T limiter is a part of the temperature control which protects the system or the process.
The Delta T limiter is given a limit value. The Delta T limiter then reacts when the limit value is
reached during heating or cooling.
The temperature control mode “Process (Cascade)” evaluates the temperature difference between
the flow temperature and the process temperature. The default setting of the limit value is 100 K. If
the limit value and the temperature sensor are set properly, the load limits, e.g. from a glass appa-
ratus, are not exceeded. As the limit value is approached, the cooling or heating capacity is adjusted.
The DeltaT limiter is
not
a safety device.
4.2.5
Monitoring the Pt100 temperature sensors
The Pt100 temperature sensors are constantly monitored for their electrical status. If the status
“Sensor faulty” occurs during temperature control, the temperature control process is stopped
immediately and a device message is displayed. This applies for all temperature sensors connected
within the temperature control unit.
Representation of an
optimum process
temperature control
Summary of Contents for Pilot ONE Unistat T3*0
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