Lem Intellectual Property Sa

Liaisons Electroniques-Mecaniques Lem Sa

Lem International Sa

Lem Heme Limited

Wolfram Teppan

Dominik Schläfli

Davide Azzoni

Stéphane Claeys

Benjamin Marcoz

Félix Buhlmann

Marc Schaerrer

Yori Hatakeyama

Hiroshi Obata

Contactless voltage transducer for measuring voltages between at least two conductors of an alternating voltage conductor system, the transducer including two or more capacitive current measurement units, each said capacitive current measurement unit comprising

Contactless voltage transducer

Electrical current transducer () of a closed-loop type for measuring a primary current (I) flowing in a primary conductor (), comprising a fluxgate measuring head () and an electronic circuit () including a microprocessor () for digital signal processing. The measuring head includes a secondary coil () and a fluxgate detector () comprising an excitation coil and a magnetic material core. The electronic circuit comprises an excitation coil drive circuit () configured to generate an alternating excitation voltage to supply the excitation coil with an alternating excitation current (I), the secondary coil () connected in a feedback loop () of the electronic circuit to the excitation coil drive circuit (), the electronic circuit further comprising a ripple compensation circuit () configured to compensate for a ripple signal generated by the alternating excitation voltage.

Current transducer with fluxgate detector

A closed-loop current transducer comprising a magnetic circuit, a magnetic field detector, and a compensation coil assembly configured to generate a magnetic field opposing a magnetic field created by an electrical current to be measured flowing in one or more primary conductors extending through a central opening of the magnetic circuit. The magnetic circuit comprises a first branch, a second branch, and first and second end branches, interconnecting the first and second branches such that the branches surround a central passage through which the one or more primary conductors may extend, the second branch forming a receptacle that defines a cavity extending in an axial direction A for receiving a sensing portion of the magnetic field detector, the second branch comprising two second branch portions separated by an interface resulting from the bringing together of opposed ends of a single piece magnetic circuit.

Electrical current transducer

Electrical current transducer comprising a measuring circuit () and an inductor () for measuring a primary current Iflowing in a primary conductor (), the inductor comprising a saturable magnetic core () made of a highly permeable magnetic material and a secondary coil () for carrying an alternating excitation i configured to alternatingly saturate the magnetic core, the coil being connected to the measuring circuit. The measuring circuit is configured to measure a mean value of the excitation current in the secondary coil and determine therefrom a value of the primary current for small current amplitudes, the measuring circuit being further configured for evaluating the frequency of the excitation current i and determining therefrom the value of the primary current for large currents.

Mixed mode fluxgate current transducer

Electrical current sensor comprising a measuring circuit () and an inductor () for measuring a primary current Iflowing in a primary conductor (), the inductor comprising a saturable magnetic core () made of a highly permeable magnetic material and a secondary coil () for carrying an alternating excitation i configured to alternatingly saturate the magnetic core, the coil being connected to the measuring circuit. The measuring circuit is configured to supply a positive or negative voltage to the inductor, to switch off the voltage when a condition signalling saturation is reached, to measure the time to saturation tin one direction and the time to saturation tin the other direction of the magnetic core and determine therefrom a value of the primary current for small current amplitudes, the measuring circuit being further configured for evaluating the average value of the excitation current i and determining therefrom the value of the primary current for large currents.

Closed-loop fluxgate current sensor

Closed-loop current sensor comprising a magnetic circuit, a magnetic field sensor, and a compensation circuit configured to generate a magnetic field opposing a magnetic field created by an electrical current to be measured flowing in one or more primary conductors () extending through a central opening () of the magnetic circuit. The magnetic circuit comprises a magnetic core () made of at least two core parts () assembled together to form a substantially closed magnetic circuit, wherein a second branch () of the magnetic circuit comprises inner () and outer () wall portions joined by one or more lateral wall portions (') at least partially surrounding a cavity portion () receiving the magnetic field sensor () therein, the lateral and outer wall portions extending from one or both lateral edges of the inner wall portion.

Electrical current sensor

A fluxgate magnetic field sensor including an excitation current conductor () and a layer of saturable magnetic material cladding () having a plurality of feed-through channels () extending between opposed faces of the cladding layer, the excitation current conductor weaving through a plurality of said feed-through channels.

Thin film fluxgate sensor

Sensor for measuring electrical parameters in a high voltage environment comprising a high voltage side () for connection to high voltage conductors, a low voltage side () for connection to low voltage power supply and measurement signal control circuitry, a measurement signal circuit (), and a power supply circuit (), and at least one isolating transformer () for transmission of electrical power supply and/or measurement signals between the low voltage side and the high voltage side. The isolating transformer comprises at least a first and a second transformer core (), a transformer coil () on a circuit board around a branch () of the transformer core on the high voltage side and a transformer coil () on a circuit board around a branch () of the transformer core on the low voltage side, the isolating transformer further comprising an intermediate coil () encircling at least one branch of each said at least two transformer cores.

Sensor for high voltage environment

A magnetic field sensor comprises a magnetic field sensing cell and a magnetic shield comprising at least two parts separated by an air-gap and surrounding the magnetic field sensing cell positioned in a cavity of the magnetic shield.

Growing community of inventors

Wünnewil, Switzerland

Wolfram Teppan