NAMUR 2-W Proximity Sensor

Test Circuit

NAMUR test circuit

U0 = 8.2 Vdc Iactivated ≤ 1.2mA
Ri = 1000W Inon-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 + Δs.

NAMUR Characteristic

NAMUR Switching Characteristictest

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.

NAMUR sensors can operate also outside the nominal operating values usually between 5 and 39Vdc.

Note: If a NAMUR input is specified on an APCS product then a 8V supply will be generated internally to supply the sensor.

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

The following table gives typical values over the extended voltage range:

U (Vdc) Ri(kΩ) I(sn) (mA) ΔI (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.

Ness Corporation