Glossary · Sensors and measurement
Two-wire transducer
Also known as: 2-wire transducer
German: Zweidraht-Messumformer
In instrumentation, a two-wire transducer is a measuring transducer that is connected with only two wires, through which it receives its power and transmits its signal, typically as a 4–20 mA current. The term is largely used as a synonym of two-wire transmitter.
- Sensors
- Process industry
In one sentence
A two-wire transducer gets its power and sends its signal over the same two wires, usually as a 4–20 mA current.
Example
A two-wire transducer mounted in the head of a temperature sensor converts the Pt100 signal into 4–20 mA over the same pair of wires that powers it.
How it applies
- Engineering: The device takes its supply from the loop current, so its own consumption must stay below the minimum signal current, which is why two-wire devices use a live zero such as 4 mA.
- Wiring: The loop needs a supply voltage high enough for the device's minimum voltage plus all voltage drops in the loop, such as input resistors and barriers.
- Documentation: The list contains both two-wire transducer and Two-wire transmitter for the same German concept. Use one term consistently within a document set, preferably two-wire transmitter for process instruments, and mention the other as a synonym.
Two-wire transducer vs. two-wire transmitter
The terms describe the same wiring concept. Transducer emphasizes signal conversion; transmitter emphasizes transmission of a standardized signal. Catalogs use both.