What is a 2-wire loop powered transmitter?

What is a 2-wire loop powered transmitter?

• A. A transmitter that receives its power from the same two wires that carry the 4-20 mA signal
• B. A wireless transmitter
• C. A battery-powered transmitter
• D. A transmitter powered from separate supply

Answer: (A)

In a two-wire loop-powered transmitter, power and signal share the same two conductors of the 4-20 mA loop. The transmitter sits in series with the loop and draws operating power from the loop supply while its internal electronics modulate the loop current to encode the measured value. No separate power source or battery is needed; power comes from the loop itself. This distinguishes it from wireless transmitters, battery-powered units, or devices with a separate supply.

In a two-wire loop-powered transmitter, power and signal share the same two conductors of the 4-20 mA loop. The transmitter sits in series with the loop and draws operating power from the loop supply while its internal electronics modulate the loop current to encode the measured value. No separate power source or battery is needed; power comes from the loop itself. This distinguishes it from wireless transmitters, battery-powered units, or devices with a separate supply.