Specifications

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Siemens FI 01 · 2015 US Edition
Temperature Measurement
Transmitters for field mounting
SITRANS TF fieldbus transmitter
2
■ Overview
Our field devices for heavy industrial use
• FOUNDATION fieldbus
• PROFIBUS PA
The SITRANS TF temperature transmitter works where others
can’t cope.
■ Benefits
• For universal use as a transmitter for resistance thermometers,
thermocouple elements,  or mV signals
• Rugged two-chamber enclosure in die-cast aluminium or
stainless steel
• Degree of protection IP67
• Can be mounted elsewhere if the measuring point
- is hard to access,
- is subject to high temperatures,
- is subject to vibrations from the system,
- or if you want to avoid long neck tubes and/or protective
tubes.
• Can be mounted directly on American-design sensors
• Wide range of approvals for use in potentially explosive atmo-
spheres. "Intrinsically safe, non-sparking and flameproof" type
of protection, for Europe and USA
■ Application
The SITRANS TF can be used everywhere where temperatures
need to be measured under particularly harsh conditions. Which
is why users from all industries have opted for this field device.
The rugged enclosure protects the electronics. The stainless
steel model is almost completely resistant to sea water and other
aggressive elements.
The inner workings offer high measuring accuracy, universal in-
put and a wide range of diagnostic options.
■ Function
Features
• Polarity-neutral bus connection
• 24-bit analog-digital converter for high resolution
• Electrically isolated
• Version for use in hazardous areas
• Special characteristic
• Sensor redundance
Transmitter with PROFIBUS PA communication
• Function blocks: 2 x analog
Transmitter with FOUNDATION fieldbus communication
• Function blocks: 2 x analog and 1 x PID
• Functionality: Basic or LAS
Mode of operation
The following function diagram explains the mode of operation
of the transmitter.
The only difference between the two versions of the SITRANS TF
(7NG3137-... and 7NG3138-...) is the type of field bus protocol
used (PROFIBUS PA or FOUNDATION fieldbus).
SITRANS TF with TH400, function diagram
Optional inputs:
- Resistance thermometer
- Thermocouple
- mV sensor
- Resistance-based sensors
Input 1
Input 2
Transformer
Input 1
Input 2
Differential
Mean value
Redundancy
Terminal temperature
Engineering units
Diagnostic functions
Table linearization
Polynomial linearization
Process calibration
A/D
converter
Complex configuration
Correction coefficient
Factory settings
- PROFIBUS PA protocol (7NG3137)
or
- FOUNDATION Fieldbus protocol
(7NG3138)
Bus connection
Ex power circuit
Electrically
isolated
Internal
Pt100
Communication
CPU
2
1
EEPROM
6
5
4
3
© Siemens AG 2015