2-Wire Sensors

2-wire sensors according to NAMUR (NAMUR sensors) are named after the User Association of Automation Technology in Process Industries (original German name: "Normenarbeitsgemeinschaft für Mess- und Regeltechnik der chemischen Industrie", in short: NAMUR). These are two-wire sensors according to EN 60947-5-6 (VDE 0660, part 212) that have a continuous or a noncontinuous distance/current characteristic.

Area 0: unactuated area
Red area between 0/I: impermissible area of the switch amplifier
Area I: actuated range
Area ≤ 0.15 mA: lead breakage
Area ≥ 6.5 mA: short circuit

In addition, Pepperl+Fuchs offers NAMUR sensors with binary switching characteristics. NAMUR sensors with this output characteristic are marked with "N0" (normally-closed characteristics) or "N1" (normally-open characteristics) in the type designation.

Area 0: unactuated area
Red area between 0/I: impermissible area of the switch amplifier
Area I: actuated range
Area ≤ 0.15 mA: lead breakage
Area ≥ 6.5 mA: short circuit

Sensor Connection—Example

Pepperl+Fuchs offers various switch amplifiers for NAMUR sensors for explosion-protection applications and standard applications.

Note: In explosion-protection applications, the operating location of the intrinsically safe NAMUR sensor is located in the explosion-hazardous area. The isolated switch amplifier must be installed outside the explosion-hazardous area.
A blue-sheathed sensor cable visually identifies the NAMUR circuit as intrinsically safe.

Example:

NAMUR Sensor Versions

NAMUR sensors are marked with the following in the third block of the Pepperl+Fuchs order designation:

–N = continuous distance/current characteristic or

–N0 = non-continuous distance/current characteristic

The sensors are available in the following switching functions:

• Normally-closed (N/N0)
• Normally-open (1N/N1)
• Normally-closed 2-channel (N4)

NAMUR sensors are usually connected to external switch amplifiers that convert the current variation into a binary output signal.