Itron Gmbh

Itron Electricity Metering, Inc.

Brent Martin

Brian Keith Seal

Michael E Moore

Daniel M Lakich

The present technology involves a method and apparatus for detecting and reporting magnetic fields in the proximity of a utility meter as an approach to determining tampering of such meter. The sensitivity level of the magnetic field sensors may be adjustable allowing either remote or local sensitivity adjustments to a magnetic field sensor to compensate for variations in the electromagnetic environments of different meter installation sites. Alternatively, the output of each magnetic field sensor may be connected to the input of an adjustable threshold circuit. When the output voltage of the magnetic field exceeds a predetermined threshold voltage, a magnetic event signal is generated. Threshold adjustments to the adjustable threshold circuit may be performed locally at the meter site or remotely from a station. The output of each magnetic field sensor may be monitored by a locally or remotely programmable magnetic sensor output monitor. Such magnetic sensor output monitor generates a magnetic event signal when a predetermined number of magnetic sensors have been activated.

Magnetic field sensing for tamper identification

A voltage acquisition circuit for sensing input voltage signals in each phase of an electrical service includes a non-active current transformer configuration that is operable over a wide input voltage range. The current transformer configuration includes primary and secondary windings, an input resistor and a burden resistor across which an output voltage is defined. The input resistor may be relatively large, such as on the order of about one M&#x3a9; and the transformer core may have a nanocrystalline core characterized by predictable magnetic properties versus varied transformer flux levels. This operational predictability facilitates phase compensation via digital filtering or otherwise for any phase shift induced between input and output voltages of the current transformer.

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Walhalla, SC, United States of America

Brent Martin