Flow Ctrl Tech Engineering

Troubleshooting 4-20mA Current Loops: Open Loops, Ground Faults & Power Sag

Field engineer diagnostic checklist for solving analog sensor errors: measuring loop current in-series, detecting ground loops with Fluke 771 clamp meters, and diagnosing loop power sag.

  • A reading of 0.0mA indicates an open circuit (broken wire, blown fuse, loose terminal screw).
  • A reading pinned at ~3.8mA or ~21.5mA indicates an internal NAMUR NE43 sensor diagnostic fault.
  • Fluke process clamp meters measure loop milliamp current without opening the physical terminal circuit.

Flow Ctrl Tech Engineering: Turnkey industrial automation, PLC programming, SCADA development, HMI, fieldbuses, and IIoT architectures. Contact our engineering center at [email protected] or phone +91 91110 91005.