Measurement of current within a conductor

Patent metadata

Field	Value
Publication number	US-11022630-B2
Application number	US-201716332860-A
Country	US
Kind code	B2
Filing date	Sep 14, 2017
Priority date	Sep 15, 2016
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

In the field of Rogowski coils for the measurement of current within a conductor there is provided an electrical interface for connection to a Rogowski coil arranged around a primary conductor. The electrical interface includes an input that is configured to sample an input voltage signal from the Rogowski coil. The electrical interface also has an integrator circuit which includes an integrator module that is configured to integrate the sampled input voltage signal to provide an output voltage signal from which can be derived a primary current flowing through the primary conductor. The integrator module employs a transfer function that includes an attenuation factor.

First claim

What we claim is:

1. An electrical interface, for connection to a Rogowski coil arranged around a primary conductor, comprising:
an input configured to sample an input voltage signal from the Rogowski coil; and
an integrator circuit including an integrator module configured to integrate the sampled input voltage signal to provide an output voltage signal from which can be derived a primary current flowing through the primary conductor, the integrator module employing a transfer function that includes an attenuation factor, and the integrator module further employs the transfer function or a different transfer function which additionally down-samples a previous output voltage signal.

2. The electrical interface according to claim 1 , wherein the attenuation factor gives rise to an error in the derived primary current flowing through the primary conductor that is not greater than a predetermined percentage selected according to the nature of the primary current flowing through the primary conductor.

3. The electrical interface according to claim 2 , wherein the percentage error in the derived primary current is selected to be:
not greater than 10% when the primary current is decaying; and
not greater than 0.3% when the primary current is in steady state.

4. The electrical interface according to claim 1 , wherein the integrator module is or includes one or more of:
a first rectangular integrator embodying a transfer function in the discrete time domain of the form

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a second rectangular integrator embodying a transfer function in the discrete time domain of the form

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a trapezoidal integrator embodying a transfer function in the discrete time domain of the form

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Assignees

• General Electric Technology Gmbh

Inventors

• Ha Hengxu
• Souza Celso
• Bernardi Davi
• Zeng Xianwu
• Bencz Elias

Classifications

• G06F7/64

  Digital differential analysers, i.e. computing devices for differentiation, integration or solving differential or integral equations, using pulses representing increments; Other incremental computing devices for solving difference equations (G06F7/70 takes precedence; differential analysers using hybrid computing techniques G06J1/02 {; DDA application in numerical control G05B19/18}) · CPC title

• G01R19/0015

  separating AC and DC · CPC title

• G01R19/2509

  Details concerning sampling, digitizing or waveform capturing · CPC title

• G01R19/32

  Compensating for temperature change · CPC title

• G01R19/16528

  using digital techniques or performing arithmetic operations (using digital techniques to measure a voltage or a current, see G01R19/25) · CPC title