Patent ID: 11971380
Assignee: GRUNDFOS HOLDING A/S
Field: Measurement (Instruments)
Classification: CPC G  F | IPC F  G

Claim 19:
20. A sensor unit comprising:
a sensor provided for arrangement inside a conduit or space containing a liquid; and
an evaluation unit connected to said sensor, wherein said sensor and said evaluation unit are configured for detecting a concentration of a substance in a liquid by an electrical impedance measurement, wherein said evaluation unit is configured such that a measurement for detecting said concentration is carried out by use of an electrical signal applied to said sensor having at least one frequency corresponding to or above an upper cut-off frequency of a frequency range showing a constant electrical impedance, wherein a capacitance of said liquid is detected and said concentration is determined based on said capacitance, wherein said capacitance is determined by detecting a resistance of said liquid and said upper cut-off frequency and/or detecting a resonance frequency of a resonator influenced by a capacity of said liquid.