Difference betwen Namur and Reed Sensor

http://www.reed-sensor.com/Applications/

joshua

Reed relays have potential free contact and do not produce voltage or sink/source current. Hence, Reed require external voltage to be switched.

Namur is a low voltage signal in the 40mV-200mV which can also be from 4-20mA if dropped across a 10 ohms resistance. Normally larger sense resistance of 100 Ohms is used to get 400mV-2V output from 4-20mA. More about Namur you can look at sensors from www.turck.com or www.banner.com

You can also search for Namur Signal Transmitters.

Thank you Shyam. Now I can understand better.

Regarding this, that is the reason because the NAMUR sensor needs an amplifier in many applications, because the low voltage is not able to exite the equipment relay.

In this case, how can I identify a Namur sensor to find out the correct amplifier.

Thank you !

Normally a voltage comparator with variable reference voltage can easily differentiate 0/1 of the Namur signal and then use a relay or power transistor / MOFET driver from comparator weak signal.

You also have to properly terminate the Namur signal and also use small filter capacitor just enough to kill noise but not the signal.

Namur signal may come from Hall Effect gear tooth sensor that may have frequency up to 10kHz and such signals require good quality input stage design.

For industrial hardware, it is always good to take help of an expert as you may affect the process badly with wrong design. Only expert knows the likely problems from experience. Learning and doing it is not a bad idea. However industrial hardware requires many considerations such as isolation of 1500V, supply voltage tolerance from 10V to 30V, lots of noise filtering, low input current and surge protection to have some feeling of it.

what do you mean by hall sensor frequency 10khz will you please explain.

as i work in magnetic field

motor / generator rpm sensor using tooth position sensed by Hall Effect sensor generates pulses for every pass of tooth. Optical sensors / encoders generate fast pulse trains up to 10kHz. Look at

www.banner.com

www.turck.com

www.automationdirect.com and other web sites

Attention please:

The one who need reed sensors or switches,please contact Maggie.thanks.

Web: www.reedsensor.com.tw

Email: maggie@geding.com.tw

Here's a link that has all the TURCK NAMUR sensors.

http://www.clrwtr.com/TURCK-Intrinsically-Safe-Sensors.htm

Namur Sensors operate as described below. Putting it simply, when a Namur sensor "sees" a target, the resistance goes from low to high. This is the opposite (in a manner of speaking) to the action of a conventional limit switch where normally the resistance goes from high (infinity) to low (connected) when the switch is activated. This characteristic causes confusion frequently.

M.Z.

Most of the people do not know the low and high voltage levels of Namur output signal level and what are the minimum and maximum or permitted error band for Namur signals. Being low active or high active is another point to be considered in the design. I think that is not a serious problem.