Abstract: A current sensing device particularly for rotor ground fault detection in a highly inductive field is able to sense and identify the location of low order fault current when the load current in conductors is on the order of at least 1,000 amperes. Laminated strips of magnetic material are flexible to be located ideally about the conductors to maximize the sensitivity signal and minimize the effect of electromagnetic radiation. The current sensor includes three sets of laminations, the central laminations being for magnetization sensing, the inner laminations being for magnetic filtering, and outer laminations being for magnetic shield. Magnetic separation exists between each lamination set. Electrical insulation is located about the inner and outer sets.

Abstract: Apparatus for the detection of leakage current in a system includes a power supply and conductors from the supply for supplying power to a load connected to the system. There is an interrupter connected in the system and to a ground point such that a ground leakage current in the system has a closed circuit. Activation of the interrupter about every 12 seconds effectively generates a pulse interrupted ground fault signal. Such signal is detected by a magnetic sensor located relative to a multi-feeder system with high capacitive reactance. The sensor is immune to random electromagnetic and electrostatic conditions in the distribution system. The sensor is synchronized to operate with the interrupter so that sensing is effected at a steady level of a square wave interrupted pulse.