Thermocouple transmitters generally produce 0-15 mA output signals.

• A. True
• B. False
• C. 1-5 V
• D. 4-20 mA

Answer: (B)

Thermocouple transmitters convert the tiny millivolt signal from the sensor into a signal that is easy to read over long distances and in noisy environments. The standard output for this kind of transmitter is a current loop, typically 4 to 20 mA, with 4 mA representing zero input and up to 20 mA representing the maximum temperature signal. This live-zero arrangement helps detect faults (like a broken wire) because a current of 0 mA would indicate a problem, not just a low measurement. A range like 0-15 mA isn’t used because it wouldn’t align with the common 4-20 mA standard and would reduce fault detection and compatibility with controllers and field devices. Some devices do offer voltage outputs (for example, 1-5 V), but the widely adopted, reliable choice for thermocouple transmitters in process control is 4-20 mA.