Industrial Engineer · phase 2 of 16 · noun
Two-Wire Transmitter
Analog transmitter powered through the same current loop that carries its measurement signal.
The Explain card
- Plain English
- A two wire transmitter runs on the same pair of wires that carry its signal. The loop current powers the electronics and reports the measurement at the same time.
- Example
- A pressure transmitter has just two terminals. The analog input card, or a separate loop supply, pushes 24 V into the loop and the transmitter regulates the current between 4 and 20 mA.
- Why it matters
- Two wires mean cheaper runs and fewer terminals, and the transmitter cannot draw below 4 mA because it needs that much to stay alive. A loop that reads zero is broken, never merely at the bottom of scale.
- Hook
- The signal wire is the power cord.
Word knowledge
How the word is built, where it came from, and what it sits beside in memory.
In a sentence
The technician connected the two-wire transmitter to a 24 VDC supply and verified its 4–20 mA output at the PLC input.
Why these words
- two-wire Old English twā plus Old English wīr compound modifier specifying the conductor arrangement
- transmitter Latin transmittere, to send across, through English transmit plus -er head noun naming the field device
Where it came from
- Origin
- English engineering compound formed from two, wire, and transmitter
- Entered the language
- 1960s
- What changed
- Transmitter shifted from a general agent that sends something to a technical device, while two-wire became a standard electrical configuration label.
How it is spelled
- Pattern
- Two-wire is hyphenated when the two words jointly modify transmitter.
- Pattern
- Transmitter doubles the final t of transmit before the agent suffix -er.
- Breaks the pattern
- The w in two is silent in modern English.
Spelled like
- three-wire sensor
- four-wire transmitter
- committer
- admitter
Broken into chunks
-
two-wire
- two-wire sensor
- two-wire circuit
-
transmit
- transmission
- transmittal
-
-er
- controller
- converter
What it sits beside
Same subject
- 4–20 mA loop
- analog input module
- 24 VDC power supply
- HART communicator
Same shape
- three-wire sensor
- four-wire transmitter
- two-wire circuit
transmitter wiring configurations
- two-wire transmitter
- three-wire transmitter
- four-wire transmitter
industrial analog instruments
- pressure transmitter
- temperature transmitter
- level transmitter
Where it sits in the deck
Phase 2: PLC I/O and Field Signals
Where the controller meets the machine: discrete and analog signals, the wiring conventions behind them, and the field devices that send them.
