Through the special input coupling of a high-frequency, electromagnetic alternating field, a homogenous measuring field is generated in the measuring pipe. Solids within this measuring field reduce the amplitude of this alternating field. This leads to a measuring signal corresponding to the concentration of the solids being conveyed in the measuring tube (kg/m3).
Using the same kind of sensor, the change of the alternating field is measured within the measuring tube at two additional points. These two sensors have a defined distance to each other.
The analysis electronics with its integrated correlator determines the runtime of the conveyor belt between the both sensors from the two sensor signals. The known distance is then used to determine the speed of the solid (m/sec).
The two measured parameters concentration (K) and speed (v) as well as the known profile (A) of the measuring tube, the flow is determined as
Q = K x v x A
and output as a 4 … 20 mA signal.