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Signals and PLC · Glossary

What is a NAMUR Sensor?

two wire proximity switchSignals and PLC

A NAMUR sensor is a two wire proximity sensor that signals by changing its current, used with isolating amplifiers and in intrinsically safe circuits.

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NAMUR Sensor Explained

At about 8.2 V supply, the sensor draws below 1.2 mA in one state and above 2.1 mA in the other, as defined in EN 60947-5-6. The amplifier also detects open and short circuits.

The low power suits Ex i installations and line fault detection for safety.

NAMUR Sensor: Typical Values

Supplyabout 8.2 V via about 1 kΩ
Off state≤ 1.2 mA
On state≥ 2.1 mA
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Calculators for NAMUR Sensor

CalculatorNAMUR Sensor CalculatorFree online calculator with formula and worked example.

Frequently Asked Questions

What is a NAMUR Sensor?

A NAMUR sensor is a two wire proximity sensor that signals by changing its current, used with isolating amplifiers and in intrinsically safe circuits.

Can a NAMUR sensor connect directly to a PLC input?

Not to a normal 24 V input; it needs a NAMUR amplifier or a NAMUR input card.

What is line fault detection?

The amplifier sees open circuits (very low current) and shorts (very high current) as faults.

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