Liaisons Electroniques-mecaniques Lem Sa

Liaisons Electroniques-mechaniques Lem S.a.

Claude Gudel

Pierre Cattaneo

An open-loop current sensor comprising a magnetic circuit having an air gap, a magnetic field detector disposed in the air gap, and a primary conductor having one or more turns surrounding the magnetic circuit, the current to be measured flowing in the primary conductor, the sensor being characterised in that the turns of the primary conductor are disposed close to the air gap, on each side of the air gap.

Open-loop electric current sensor and a power supply circuit provided with such sensors

The invention concerns a sensor including a magnetic circuit coupled with a primary conductor, a secondary winding coupled with the magnetic circuit, a damping resistor, a magnetic field detector arranged in an air gap of the magnetic circuit and a powering device supplying the secondary winding with a current tending to compensate the magnetic field in the air gap. A measuring resistor is connected in series to the secondary winding and an auxiliary resistor of same value as the damping resistor is connected to the secondary winding and the measuring resistor common connection point. A difference amplifier set is arranged for measuring the voltage at the secondary winding terminals and applying, to the auxiliary resistor, a voltage equal and in opposite direction to the one occurring at the secondary winding terminals.

Electric current sensor with wide passband

A magnetic circuit is coupled with a primary conductor in which flows the current to be sensed. The magnetic circuit has at least one air gap with a magnetic field detector and is coupled with at least one measuring coil producing a magnetic flux for compensating the flux generated by the primary current. The necessary current in the measuring coil to achieve such flux compensation is a measure for the primary current. A magnetic shielding part is provided in the vicinity of the air gap inside the measuring coil.

Electric current sensing device

A magnetic circuit is coupled with a primary conductor in which flows the current to be sensed. The magnetic circuit has an air gap with a magnetic field detector and is coupled with a measuring coil producing a magnetic flux for compensation the flux generated by the primary current. The necessary current in the measuring coil to achieve such flux compensation is a measure for the primary current. A yoke part of high magnetic permeability is arranged in the vicinity of the air gap inside the measuring coil so as to form a magnetic shunt between the two magnetic circuit portions forming the air gap.

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Le Pas de l'Echelle, France

Claude Gudel