Gas Fitter Practice Test

What is the millivolts power output on a thermocouple closed circuit test?

1. A. 20 to 30 millivolts

2. B. 10 to 15 millivolts

3. C. 2 to 4 millivolts

4. D. 10 millivolts or less

The correct answer is: B. 10 to 15 millivolts

In a thermocouple closed circuit test, the typical power output measured in millivolts usually falls within the range of 10 to 15 millivolts. Thermocouples work on the principle of thermoelectric effect, where two dissimilar metals produce a voltage when subjected to a temperature gradient. The output voltage is directly related to the temperature difference between the measurement and reference junctions. This specific range, 10 to 15 millivolts, is common for many thermocouples used in various applications, indicating that the thermocouple is functioning correctly and sensitive to the temperature changes it's designed to measure. When the output deviates significantly from this range, it may suggest issues such as poor connections, malfunctioning protections, or even incorrect temperature readings. Other ranges provided in the options are not typical outputs for a properly functioning thermocouple in a closed circuit. While certain thermocouples might produce voltages outside of the 10 to 15 millivolt range under specific conditions, the mentioned range is the most standardized and expected output for general applications, reinforcing the choice of 10 to 15 millivolts as the correct answer.