Glossary · Sensors and measurement
Transmitter
Also known as: Measuring transmitter, Field transmitter
German: Messumformer
In process instrumentation, a transmitter is a device that converts the signal of a sensor into a standardized output signal, such as 4–20 mA, often with HART, or a fieldbus value, so that it can be transmitted to a control system.
- Sensors
- Process industry
In one sentence
A transmitter converts a sensor signal into a standardized output such as 4–20 mA or a fieldbus value for transmission to the control system.
Example
A head-mounted temperature transmitter converts the Pt100 resistance into a 4–20 mA signal that is wired to the DCS.
How it applies
- Engineering: Transmitters linearize, scale and filter the sensor signal and provide diagnostics. Wiring type (two-, three- or four-wire) and output must match the input card.
- Commissioning: Configure range, units, damping and failure behavior. The failure current, for example according to NAMUR NE 43, must be understood by the control system.
- Maintenance: Configuration data should be backed up and documented, so a replacement transmitter can be set up identically.
- Documentation: Record tag, range, damping and failure signal in the instrument list. A damping value set too high hides fast process changes and should be visible to reviewers.
Transmitter vs. sensor
The Sensor responds to the process quantity. The transmitter conditions that signal for transmission. Many devices integrate both and are then called transmitters as a whole.