SIEMENS SITRANS TH420 Temperature Transmitter


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Siemens SITRANS TH420 transmitter, featuring dual inputs, offers versatile usage across all industries. Its compact design allows for installation in connection heads of type B or larger. With its universal input module, redundant operation (high input availability) is supported, enabling connection of the following sensors and signal sources:

  • 2 resistance thermometers (2-wire, 3-wire, 4-wire connection)
  • 2 thermocouples
  • 2 linear resistors, potentiometers, and DC voltage sources


The output signal comprises a load-independent direct current from 4 to 20 mA, aligned with the input characteristic, and augmented by the digital HART signal.

The dual input mode facilitates drift detection of inputs, enabling more efficient maintenance planning.

Transmitters designed for “intrinsically safe or Zone 2 increased safety” protection can be safely deployed in hazardous areas. Compliant with EU Directive 2014/34/EU (ATEX), FM, CSA regulations, and other national standards, these devices ensure reliability and safety in diverse environments.

  • Compact design
  • Connection of two independent input circuits for redundant operation (high input availability)
  • Flexible mounting and center hole allow you to select your preferred mounting type
  • Galvanic isolation
  • Test terminals for ammeter
  • Diagnostics LED (green/red)
  • Input monitoring wire break, short-circuit and drift
  • Self-monitoring
  • Configuration status stored in EEPROM
  • SIL2/3 (with order note C20)
  • Expanded diagnostic functions, such as slave pointer, operating hours counter, etc.
  • Special characteristic
  • Electromagnetic compatibility according to EN 61326 and NE21

Product Data Sheet – Siemens SITRANS TH420 Temperature Transmitter

Operation Manual – Siemens SITRANS TH420 Temperature Transmitter


Application Temperature Transmitter

(Measuring Range)

Resistance thermometers, thermocouples, resistance-type sensors, DC sources
Output 4 … 20mA (SITRANS TH320), HART (SITRANS TH320/420)
Measuring Accuracy Dependent on configuration
Operating conditions Standard: -50 … +85 °C (-58 … +185 °F)
SIL: -40 … +80 °C (-40 … 176 °F)
Degree of Protection Enclosure




Weight 50 g (0.11 lb)
Electrical Connections Wired direct
Explosion Protection IECEx
General Approvals SIL2/3
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SIEMENS SITRANS TH420 Temperature Transmitter

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