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4-20 mA Scaling Equation:
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4-20 mA scaling is a standard industrial signal range used for process control and instrumentation. The 4 mA represents the minimum process value (0%) while 20 mA represents the maximum process value (100%), providing both signal transmission and fault detection capabilities.
The calculator uses the 4-20 mA scaling equation:
Where:
Explanation: The equation linearly scales any process value between the defined minimum and maximum range to the corresponding 4-20 mA signal.
Details: 4-20 mA signals are widely used in industrial automation because they're immune to electrical noise, can transmit over long distances, and the 4 mA "live zero" allows detection of broken wires or failed sensors (0 mA indicates a fault).
Tips: Enter the current process value, the minimum expected process value (corresponding to 4 mA), and the maximum expected process value (corresponding to 20 mA). Ensure Max > Min for valid calculation.
Q1: Why 4-20 mA instead of 0-20 mA?
A: The 4 mA "live zero" allows distinguishing between a true zero signal and a broken wire or sensor failure (which would show 0 mA).
Q2: What if my process value exceeds the min-max range?
A: The calculated mA will be below 4 mA (if below min) or above 20 mA (if above max), indicating out-of-range conditions.
Q3: Can this be used for reverse acting signals?
A: Yes, simply set Min to the high value and Max to the low value for reverse acting applications.
Q4: What are typical applications?
A: Pressure transmitters, temperature sensors, flow meters, level sensors, and various process instruments.
Q5: How accurate is this calculation?
A: The calculation provides theoretical values. Actual accuracy depends on instrument calibration and environmental factors.