Live-zero signal
The live-zero signal is a standard signal that serves as a current or voltage signal for the analog transmission of a process variable to the PLC, for example.
Current signals to DIN IEC 60381-1
- 0 mA ... 20 mA
- 4 mA ... 20 mA ("live-zero")
Voltage signals to DIN IEC 60381-2S
- 0 V ... 10 V
- 2 V ... 10 V ("live-zero")
Live-zero signals are currently used in almost all industrial applications, whereby a non-zero electrical signal is assigned to the start of the measuring range, enabling monitoring for broken wires.
In this example, the non-zero starting signal of 4 mA or 2 V is the "live zero", whereas signals 0 mA and 0 V always point to a fault.
Since current signals are less sensitive to electromagnetic interference as occurs when adjacent consumers are activated, and voltage loss caused by line resistance is anticipated, this type of signal is preferred over voltage signals.
