Why is the 4-20mA Signal Used in Industrial Applications
The 4-20mA analog signal is the most widely used standard in industrial environments. But why?
Reasons:
1. Noise Resistance:
In industries, motors, VFDs, and heavy electrical equipment create interference. Voltage signals (0-10V) are easily distorted here. But 4-20mA signals are highly resistant to electromagnetic interference (EMI).
2. Long Distance Transmission:
Current signals do not degrade over long cable runs. Even beyond 100 meters, you still get accurate readings.
3. Fault Detection:
4mA = Zero process signal,
0mA = Broken wire!
So if the cable breaks or the sensor fails, it's immediately noticeable.
4. Accuracy:
Voltage signals suffer from voltage drops due to wire resistance. Current signals don’t. Hence, 4-20mA provides more accurate readings.
Example:
Temperature, Pressure, and Flow Transmitters – most of them use 4-20mA.
Conclusion:
"Simple setups use voltage, but industrial reliability demands current."
Do you also use 4-20mA signals? Share your experience in the comments!
