Question 559General Subjects - Assistant Engineer70% to pass
For an analog electronic transmission system for instrumentation purposes, if an analog pressure indicator has a calibrated scale of 0 to 30 psig, what would be the actual measured pressure if the transmitted analog signal current to the indicator is 12 mA, assuming the industry standard of 4 to 20 mA is used for instrument current?
AI Explanation
The correct answer is C) 15 psig.
In an analog electronic transmission system, the industry standard of 4 to 20 mA is used to represent the full range of the instrument's calibrated scale. In this case, the pressure indicator has a calibrated scale of 0 to 30 psig. At 4 mA, the indicator would read 0 psig, and at 20 mA, it would read 30 psig. Since the transmitted signal is 12 mA, which is the midpoint of the 4 to 20 mA range, the actual measured pressure would be 15 psig, which is the midpoint of the 0 to 30 psig calibrated scale.
The other options are incorrect because they do not accurately reflect the relationship between the 4-20 mA signal range and the 0-30 psig calibrated scale.
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