Patent ID: 8354836

Claim:
Process for detecting electrically conductive particles in an electrically nonconductive liquid flowing in a pipe section, comprising the steps of: inducing eddy currents in the particles in the flow of electrically nonconductive liquid by means of a transmitter coil surrounding the pipe section, outputting a difference signal according to the eddy currents induced by the transmitter coil by means of at least one first inductive receiver coil surrounding the pipe section and a second inductive receiver coil which is spaced axially relative to the first receiver coil and which surrounds the pipe section, the receiver coils being located in a region of the transmitter coil and being subtractively connected in a manner causing the transmitter coil to form a primary side and the receiver coils to form a secondary side of a transformer arrangement, and evaluating the difference signal to detect passage of electrically conductive particles in the pipe section and the position of detected particles within the pipe section, using the evaluation of the difference signal to determine particle concentration in the liquid, and determining the state of a machine though which the liquid has passed from said particle concentration, wherein a radial distance of the detected particles from a wall of the receiver coils is estimated from the difference signal, and wherein a flow velocity of the detected particles flowing in the pipe section is estimated from the difference signal.