Des cription
Note: This article attempts to show the operating range and general characteristics of the NAMUR sensor. The extended voltage range of the sensor may not be applicable to all manufacturers NAMUR sensors. If A.P.C.S. has a NAMUR input specified on a module a 8V supply will be generated internally to supply the sensor.

NAMUR-sensors are polarised 2-wire sensors which change their internal resistance depending on the distance of target (constant distance / current characteristic). They are designed for use with external amplifiers, which convert the current changes into a binary (on/off) output signal.

U0 = 8.2 Vdc I activated <= 1.2mA
Ri = 1000 ohm I non-activated >= 2.1mA

Most NAMUR sensors are specified in the middle of the "NAMUR-window" at 1.55mA for sn and 1.75mA for sn + Delta s (see characteristics). NAMUR-sensors can operate also outside the nominal operating values, if the following limit values are not exceeded:
?Umin = 5 Vdc
?Umax = 30 Vdc
Note that different operating values (U, R,) counteract a change of the switching distance.

Within the admissible voltage range it is necessary to adopt the resistance Ri, as well as the current in the switching point I(Sn).


The following table gives typical values:

U (Vdc) Ri(W) I(sn) (mA) DI (mA)
5 0.39 »0.7 » 0.1
12 1.8 » 2.3 » 0.3
15 2.2 » 2.9 » 0.4
24 3.9 » 3.8 » 0.5

If the presented values are used, the corresponding currents result in the nominal switching distance of the sensor. Short-circuit protection is guaranteed up to 15Vdc and reverse polarity protection up to 10Vdc.