Landis+gyr, Inc.

Landis+gyr Innovations, Inc.

Matt E Kraus

Frank J Boudreau, Jr

Thomas Gerard Block

A progressively contacting switch includes a set of contacts connected to an input. The set includes a first sacrificial contact formed of a first metal and a first conducting contact formed of a second metal. The switch further includes a movable set of contacts connected to an output. The movable set includes a second sacrificial contact formed of the first metal and a second conducting contact formed of the second metal. The switch includes an element configurable to connect the movable set of contacts such that the first sacrificial contact connects to the second sacrificial contact at a first time, thereby causing a current to flow from the input to the output, and while the first sacrificial contact remains connected to the second sacrificial contact, the first conducting contact connects with the second conducting contact at a later time.

Progressively contacting switch

A sensor includes a non-magnetic core having a first winding wrapped thereon. The first winding has a center tap dividing the first winding into a first winding portion and a second winding portion. The center tap is coupled to a reference voltage. The first winding portion and the second winding portion are configured to sense first AC signals, and have a balanced susceptibility to second AC signals. The differential integrating circuit is configured to provide common mode rejection of the second AC signals. The differential integrator circuit is operably coupled to the first winding portion and the second winding portion.

Method for improving common mode rejection in a rogowski coil-based circuit

A sensor includes a core, first and second windings, an integrating amplifier circuit and a DC balancing circuit. The first and second windings are wrapped around the core. The integrating amplifier circuit has a first input coupled to the first winding, and an output operably coupled to the second winding. The DC balancing circuit is operably coupled between the output of the integrating amplifier circuit and the first input of the integrating amplifier circuit.

Self-shielded DI/DT transformer for a meter

A current measurement circuit includes an integrator, first and second transformers, and a current measurement unit. The first transformer includes a first winding about a magnetic core. The magnetic core has an opening through which a current to be measured passes. The first winding is configured to generate a first current based on a first flux in the magnetic core. The second transformer includes second and third windings. The second winding is coupled to receive the first current from the first winding. The second winding has a terminal coupled to the third winding. The third winding is coupled to a first input of the integrator circuit. The output of the integrator circuit is operably coupled to provide an error current to the second transformer. The current measurement unit measures the current through the second winding of the second transformer.

Method and apparatus for detecting and compensating measurement errors due to transformer saturation in a meter

A circuit for use in a switched mode power supply comprising includes an integrated circuit, a transformer, a capacitor, a low voltage circuit and a current limiting resistor. The IC jitters the switching frequency of the switch based on a bias voltage of the integrated circuit. The IC also includes a current source configured to supply current for operation of the switching regulator when insufficient current is available from the bias input pin. The transformer includes primary, secondary and auxiliary windings. The primary winding receives a rectified line voltage and is coupled to the switch. The capacitor is coupled between the bias input pin and ground. The low voltage circuit is coupled to the auxiliary winding, and provides current to the bias input pin. The current limiting resistor limits current produced by the low voltage circuit to less than that required for operation of the IC.

Method and apparatus for offline switch mode power supply with dithered switching frequency

An arrangement for use in a utility meter includes a sensor and a processing circuit supported by a base of the meter, and a magnetic element carried by the cover of the meter, in which the cover is removably mounted to the base. The sensor includes at least two magnetizable elements, such as inductors, that are magnetized at opposite polarities when the meter is closed and operable. The magnetizable elements are positioned in very close proximity so that as cover is removed the magnetic element passes the elements to cause the magnetizable elements to assume the same polarity. The processing circuit continuously polls the magnetizable elements to evaluate their respective polarities and is configured to issue a tamper indication when the detected polarities are the same.

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Jamestown, IN, United States of America

Matt E Kraus