Schlumberger Industries, Sa

Schlumberger Resource Management Services, Inc.

Schlumberger Industries

Michel Gervais

Andrew Lancaster

Wendell W Goodwin

Farah Kobbi

Karl Heinz-Buethe

Alain G Bazin

Denise Schang

Lionel Beneteau

A Hall effect sensor or device may be used in a variety of embodiments, such as measuring current within an associated conductor by helping to measure flux density within a gap of a ferromagnetic power meter core, such as in a power meter. A high linearity interface for a Hall effect device is provided for minimizing offset effects without using complicated electronic circuits. Hall effect device is characterized by first and second opposing surfaces, first and second device inputs, and first and second device outputs. A substrate is layered adjacent to one of the first and second opposing surfaces of the Hall effect device and is electrically connected to an output pin of the Hall effect device to eliminate any effects caused by asymmetry of the voltage appearing in the channel relative to the substrate. The net effect of the high linearity interface is to eliminate any adverse effects to linearity of the system, especially at low magnetic flux levels where the output voltage of the Hall device would be relatively small compared to the offset voltage levels involved. The interface virtually eliminates adverse effects from operational amplifier input offset voltages, Hall effect device output offset voltages, and any common mode voltages.

High linearity, low offset interface for hall effect devices

&ldquo;A Hall effect sensor or device may be used in a variety of embodiments, such as measuring current within an associated conductor by helping to measure flux density within a gap of a ferromagnetic power meter core, such as in a power meter. A high linearity interface for a Hall effect device is provided for minimizing offset effects without using complicated electronic circuits. Hall effect device may include a substrate, first and second device inputs, and first and second device outputs. The substrate of the Hall effect device may be connected electrically to an output pin of the Hall device to eliminate any effects caused by asymmetry of the voltage appearing in the channel relative to the substrate. The net effect of the high linearity interface is to eliminate any adverse effects to linearity of the system, especially at low magnetic flux levels where the output voltage of the Hall device would be relatively small compared to the offset voltage levels involved. The interface virtually eliminates adverse effects from operational amplifier input offset voltages, Hall effect device output offset voltages, and any common mode voltages.&rdquo;

A Hall effect sensor or device may be used in a variety of embodiments, such as measuring current within an associated conductor by helping to measure flux density within a gap of a ferromagnetic power meter core, such as in a power meter. A high linearity interface for a Hall effect device is provided for minimizing offset effects without using complicated electronic circuits. First and second levels of modulation relative to line frequency are used to synchronize Hall effect device input switching circuits and feedback loops for improved elimination of offset signals or noise from the ultimate system output. The substrate of the Hall effect device may be connected electrically to an output pin of the Hall device or to a separate virtual ground to eliminate any effects caused by asymmetry of the voltage appearing in the channel relative to the substrate. The net effect of the high linearity interface is to eliminate any adverse effects to linearity of the system, especially at low magnetic flux levels where the output voltage of the Hall device would be relatively small compared to the offset voltage levels involved. The interface virtually eliminates adverse effects from operational amplifier input offset voltages, Hall effect device output offset voltages, and any common mode voltages.

High linearity, low offset interface for Hall effect devices

A signal processing circuit, including at least two stages of frequency modulation (25,20; 28, 31, 33) and demodulation of signals applied to or generated within that circuit, characterized in that the modulating and demodulating signal for each stage is an effective square wave and in that the ratio of the frequencies (F1, F2) of the modulating signals for the first and second stages corresponds substantially to the ratio of an even integer to an odd integer, or vice versa, such that there are substantially no common frequencies or harmonics between the first and second modulating signals.

Multiple stage frequency modulated circuit

An electricity metering device including at least one sigma-delta converter (20) adapted to output a series of digital pulses, a digital counter means (21) for summing the output of the sigma-delta converter and a signalling means (32) to deliver an output signal (38) when the sum reaches a predetermined value, characterized in that the metering device further comprises a means (32, 33) for digitally adjusting the gain of the sigma-delta converter comprising programmable digital memory means (33) adapted to store a parameter representing the gain of the metering device, the value of the parameter being externally programmable, and a digital logic means (32) for logically combining the gain parameter with the digital sum stored in the counter means to determine the number of pulses required before the predetermined value is reached and an output pulse delivered.

Electricity meter with variable gain sigma-delta converter

A modulated integrator circuit frequency modulates an input signal and has an integrator comprised of an amplifier (31) and an intregrating capacitor (35) connected across an input and an output of the amplifier. The circuit further comprises a storage capacitor (36) in addition to any switching capacitors (C) associated with the modulation of the input signal if present. The storage means (36) is connectable between the input and the output of the amplifier in parallel with the integrating capacitor. The storage capacitor stores a charge associated with the voltage of the output of the amplifier and transfer such charge to the integrating capacitor to enable reversal of the charge of the integrating capacitor in synchronism with the frequency modulation of the input signal.

Frequency modulated integrator circuit

In order to avoid attempted fraud, the reader is provided with a detector for detecting a conductor wire disposed fraudulently in the insertion passage. The detector comprises a conducting plate (50) disposed across the passage. The plate (50) is fed with A.C. (62). When a fraudulent conductor wire (46) is connected to one of the contact blades (26) of the read head (28), the detector circuit is looped by capacitive coupling between the wire (46) and the plate (50).

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Champigny sur Marne, France

Michel Gervais