Patent ID: 7675386

Claim:
An inductive counting circuit for information signal transmission in electric energy distribution grids and disposed within a transmission path, the transmission path having a shielded power cable with a power cable conductor, the circuit comprising: an inductive coupling device having a ring that encloses the shielded power cable, and a coil inductively coupled to said ring and connected to a transceiver unit, wherein a current of a superposed information signal in the power cable conductor flows through a plane defined by said inductive coupling device; and an earth wire disposed upstream of said plane defined by said inductive coupling, said earth wire connected to the power cable shield and to earth or to a potential compensation, wherein no net current flows in the shield, since there is no conductive connection from one side of said plane to an other side of said plane, other than through said plane itself, and wherein, during transmission, current of an information signal is directly induced into the conductor and, during reception, only current within the conductor is evaluated, wherein all inductive coupling devices are linked to a same phase in a transmission path having several underground cables.