Tecfluid LD61N - Manual (Page 4)

When the LD61N is connected for maximum level detection, the current of the NAMUR
circuit is “high” (> 2.1 mA) when the sensor is not in contact with the fluid (level below the
sensor), and “low” (< 1.2 mA) when the sensor is immersed.
When the LD61N is connected for minimum level detection, the current of the NAMUR
circuit is “high” (> 2.1 mA) when the sensor is in contact with the fluid (level above the
sensor), and “low” (< 1.2 mA) when the sensor is not immersed.
The LD61N incorporates a LED that indicates the current output state. With the LED ON,
the output current is high (> 2.1 mA).
5. OPERATION TEST
The operation of the installation can be checked by placing a magnet in the zone shown in
the following figure. This magnet will change the output to the opposite state. In this way
the correct installation of the instrument can be checked without having to change the level
in the tank. At the same time, the bi-colour LED will indicate the change of state of the
output.
4
6. OPERATION OF A NAMUR CIRCUIT
A NAMUR device is a sensor that indicates the different detection states by means of the
current value supplied by an amplifier circuit connected to the NAMUR device.
In addition to being able to indicate the two states ON/OFF (presence/absence of the
physical phenomena to detect), it can indicate alarm states with respect to the device
Maximum Minimum
Amplifier Circuit
Test zone
Earth Earth