WIKA TR21-C - Manual (Page 10)

14006814.01 05/2011 GB/D/F/E
10 WIKA operating instructions model TR21
GB
Pt100
4 ... 20 mA
VARIVENT ® DIN 11851
Clamp BioControl ®
4. Design and function
4.1 Description
The model TR21 miniature resistance thermometers consist of a temperature sensor and a
thermowell with a hygienic process connection.
Any change in the temperature causes a change in the resistance of the Pt100 sensor in
the temperature sensor. This change can be measured directly or can be converted into a
4 ... 20 mA signal proportional to the temperature.
The thermowell is used to adapt the thermometer to the process and protects the sensor
against harsh process conditions. Furthermore, the detachable connection from the
thermowell in the TR21-A and TR21-B variants enables the removal of the temperature
sensor without having to open the process. In this way, any hygienic risk is minimised
and it is possible to calibrate the entire measuring chain (sensor, transmitter if required,
connection cable) on site, without having to disconnect the electrical connection.
Overview of the process connections/thermowell variants
■ Miniature resistance thermometer model TR21-A with thermowell model TW22
4. Design and function
Output signal:
Temperature sensors Thermowell model TW22