Current And Voltage Standard Signals - Pepperl+Fuchs H-System Manual

H-System – Isolated Barriers and Termination Boards for HIMA
Operation
4.3

Current and Voltage Standard Signals

The following signals have established themselves as the standard:
• the 0/4 mA to 20 mA current signal
• the 0/2 V to 10 V voltage signal
The 0/1 V to 5 V voltage signal is also occasionally encountered in addition to the
0/2 V to 10 V voltage signal.
Analog sensor signals and digital frequency signals are converted into one of the
two standard signals for processing in a wide variety of measurement, regulatory
and control tasks. This offers the measurement and control technician an easy-to-
measure standard signal common to all manufacturers. Sensor signals are
converted into standard signals via signal converters.
For more diagnostic options, the NAMUR organization published NAMUR
recommendation NE43, dividing the value range of the signal (e. g. current signal)
into several areas. Valid, defined measurement value information is transferred
within the range from 3.8 mA to 20.5 mA. Failure information is available when the
signal current is < 3.6 mA or > 21 mA i. e. outside of the range for measured value
information. The same applies to the voltage signal.
Figure 4.3
1 Failure information
2 Measuring information
0 %
1
3.6 3.8 4
Signal ranges according to NAMUR NE43 (e. g. current signal)
100 %
2
20 20.5 21
1
I [mA]
29