Glossary · Process instrumentation and analytical measurement
Wire break detection
Also known as: Open-circuit detection, Line break detection
German: Drahtbrucherkennung
In automation and instrumentation, wire break detection is a diagnostic function of an input, output or switching amplifier that recognizes an interrupted signal line and reports it as a fault instead of a valid signal value.
- Process instrumentation
In one sentence
Wire break detection recognizes interrupted signal lines and reports them as faults, so a cut cable is not read as a valid value.
Example
The analog input card detects that a 4–20 mA signal has dropped to 0 mA and reports a wire break, and the control loop switches to manual mode.
How it applies
- Engineering: Detection requires a signal design that makes a break visible: live-zero analog signals, NAMUR inputs, test currents on digital inputs or monitored outputs. Dead-zero signals and simple 24 V inputs cannot detect a break on their own.
- Safety: Wire break detection contributes to diagnostics in safety functions. For de-energize-to-trip designs, a wire break leads to the safe state by design; for energize-to-trip designs, line monitoring is essential.
- Commissioning: Enable detection in the input configuration and test it by opening the circuit.
- Documentation: Specify which channels monitor wire break, the fault reaction and the alarm text, and give troubleshooting steps in the maintenance manual.
Wire break detection vs. short-circuit detection
Wire break detection recognizes an open circuit; Short-circuit detection recognizes an unintended connection. Both are needed for comprehensive line monitoring.