For an analog electronic transmission system for instrumentation purposes, if an electronic level indicator has a calibrated scale of 0 to 1800 mm, what would be the actual measured liquid level of the tank if the transmitted signal current is 12 mA, assuming the industry standard of 4 to 20 mA is used for instrument current?

Question

Accepted Answer

Option B: 900 mm. The 4-20 mA standard represents a linear span. A 12 mA signal is exactly 50% of the 16 mA span (12-4=8; 8/16=0.5). Applying this 50% factor to the 0-1800 mm range yields 900 mm, which is the actual measured liquid level in the tank.