Description
3.4 Mode of operation
SITRANS TF280 WirelessHART
Operating Instructions, 10/2010, A5E02619566-02
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3.4
Mode of operation
Measuring principle
The device contains a Pt100 sensor element (resistance thermometer) in accordance with
IEC 751/DIN EN 60751. The temperature is measured as a change in resistance. This signal
is amplified by the measuring amplifier and digitized in an analog-to-digital converter.
The digital signal is analyzed in a microcontroller and corrected with regard to linearity.
The measured value is then available to a HART master via HART FSK as well as wireless
HART.
The sensor-specific calibration data are stored in an EEPROM.
3.5
Sensor
Properties
SITRANS TF280 WirelessHART applies Pt100 resistance thermometers of Class A or B.
The sensor elements used correspond to IEC 60751 and exhibit the following properties:
● Exchangeable sense element: The terminal is located in the device housing next to the
battery clips.
● Maximum length of sensor cable: 3 m with 2-, 3- or 4-wire connection.
● Software-based detection of sensor breaks.
● Measurement in temperature range -200 °C to +850 °C.
You can find additional information on the sensor elements under Technical data (Page 85).
