plc.myforum.ro

grig100 · Member 3 Joined: 01 Jan 2015 Posts: 752

"Namur Standard" Sensors

NAMUR is a German acronym for (NormenArbeitsgemeinschaft für Mess- Und Regeltechnik in der Chemischen Industrie).
This translates to: Standardization Association for Measurement and Control in Chemical Industries.
A NAMUR sensor is a non-amplified sensor that supplies two different signal levels depending upon switch state. These signal levels are low-level current. A logic interface circuit, controller, PLC, DCS, or intrinsically safe (IS) barrier is needed to read these current levels. A NAMUR output sensor is required in installations where singular safety measures are necessary (locations with explosion hazard, or personal safety). The standards for NAMUR output sensors are EN 60947-5-6:2000 and IEC 60947-5-6:1999.
A NAMUR output sensor can be normally open or normally closed, but usually, it's normally closed. This output is solid state, so there will be some current level on the output whether it’s on or off. When you look at a NAMUR output sensor data sheet, it will list nominal voltage (8.2 V), load (1 k ohm), and current for measuring plate detected (<1>2.2 mA) (for normally closed output). Because of the low-current switching level, you'll need an amplifier or an input that is designed specifically for NAMUR. Although the sensor may be able to handle a range of voltages (7 VDC to 12 VDC or 5 VDC to 25 VDC), the voltage level should be at 8.2 VDC with 1k ohm resistance as the load.

http://www.namur.net/en/recommendations-and-worksheets/current-nena.html

This International Standard applies to proximity sensors connected for operation by a two-wire connecting cable to the control input of a switching amplifier.
The switching amplifier contains a d.c. source to supply the control circuit and is controlled by the variable internal resistance of the proximity sensor.
These devices can be used in an explosive atmosphere if they also comply with IEC 60079-11.
NOTE These devices have been defined by the German organization “Normenausschuß für Meß- und
Regelungstechnik (NAMUR)” (Office for Standardization of Measurement and Regulation Techniques).

http://www.tektron.ie/namur1.htm