TESTING CAPACITIVE LEVEL SENSORS

When installing the Capacitive Tank Level Sensors, it can occur that one does not immediately receive the expected measurement values.

Follow the instructions of this document to avoid the most common mistakes.

This article applies to the following sensors:

CHECK WIRING

The first step should be to check the wiring of your installation.

Mistakes often occur because the different sensor types must be connected in different ways, and there are also changes on the wiring depending on the instrument that’s supposed to interpret the output.

There is a separate post about the correct wiring for all different installations:

Connecting Capacitive Level Sensors

TESTING THE FUNCTIONALITY

It is possible to test the correct functionality of the sensor, by using a multimeter to measure the output current delivered by the sensor.
 
The multimeter must be set for mA measurements and the leads must be connected accordingly (refer to the manual of the multimeter manufacturer for more details).
 

Build your test setup according to the following schematics. (check for the correct sensor type)

Sensors N02-240-40x

Sensor N02-240-802

Sensors N02-240-90x 

Make sure, the switch is in the position pointing towards the center of the sensor.

When setting up the circuit as described above, the reading should be around 4.0 mA. (With sensor completely out of the water)
 
Dip the sensor in the tank and check the output current on the multimeter.
The current must increase when the water level is rising and decrease when the level is lowered.
 
  
Standard Veratron instruments (e.g. ViewLine) are calibrated to read a signal in the range of 4 mA (empty tank) to 20 mA (full tank).
 
 
To calibrate the sensor, dip it fully into water and then turn the little screw on the potentiometer until the value reaches 20mA.