Current detector and current meter

Patent metadata

Field	Value
Publication number	US-10942201-B2
Application number	US-201916371683-A
Country	US
Kind code	B2
Filing date	Apr 1, 2019
Priority date	Apr 3, 2018
Publication date	Mar 9, 2021
Grant date	Mar 9, 2021

Abstract

A current detector includes: a current sensor that is constructed using a Rogowski coil, detects a current flowing in a measured object, and outputs a detection signal corresponding to a current value of the current; a transfer line that is constructed of a distributed constant line and transfers the detection signal; an impedance converting circuit that is provided between the current sensor and the transfer line and has an input impedance equal or substantially equal to a characteristic impedance of the current sensor; an integrator circuit that integrates the detection signal inputted via the transfer line and outputs an output signal indicating a current value of the current; and a resistance circuit that has a resistance value that is equal or substantially equal to a characteristic impedance of the transfer line and is connected in series between the transfer line and the integrator circuit.

First claim

What is claimed is:

1. A current detector comprising:
a current sensor that is constructed using a Rogowski coil, detects a current flowing in a measured object, and outputs a detection signal corresponding to a current value of the current;
a transfer line that is constructed of a distributed constant line and transfers the detection signal;
an impedance converting circuit that is provided between the current sensor and the transfer line and has an input impedance that is equal or substantially equal to a characteristic impedance of the current sensor;
an integrator circuit that integrates the detection signal that is inputted via the transfer line and outputs an output signal indicating a current value of the current; and
a resistance circuit that has a resistance value that is equal or substantially equal to a characteristic impedance of the transfer line and is connected in series between the transfer line and the integrator circuit.

2. The current detector according to claim 1 ,
wherein the impedance converting circuit has an output impedance that is equal or substantially equal to the characteristic impedance of the transfer line.

3. The current detector according to claim 1 ,
wherein the impedance converting circuit is constructed of a resistor with a resistance value that is equal or substantially equal to the characteristic impedance of the current sensor and is connected in series between the current sensor and the transfer line.

4. The current detector according to claim 1 ,
wherein the integrator circuit is composed of an inverting active integrator circuit.

5. The current detector according to claim 2 ,
wherein the integrator circuit is composed of an inverting active integrator circuit.

6. The current detector according to claim 3 ,
wherein the integrator circuit is composed of an inverting active integrator circuit.

7. A current meter comprising:
a current detector according to claim 1 ; and
a meter circuit that measures the current value based on the output signal outputted from the current detector.

8. A current meter comprising:
a current detector according to claim 2 ; and
a meter circuit that measures the current value based on the output signal outputted from the current detector.

9. A current meter comprising:
a current detector according to claim 3 ; and
a meter circuit that measures the current value based on the output signal outputted from the current detector.

10. A current meter comprising:
a current detector according to claim 4 ; and
a meter circuit that measures the current value based on the output signal outputted from the current detector.

11. A current meter comprising:
a current detector according to claim 5 ; and
a meter circuit that measures the current value based on the output signal outputted from the current detector.

12. A current meter comprising:
a current detector according to claim 6 ; and
a meter circuit that measures the current value based on the output signal outputted from the current detector.

Assignees

• Hioki Electric Works

Inventors

• Nakazawa Koki
• Ikeda Kenta
• Ashida Yutaka

Classifications

• G01R19/0023 Primary

  Measuring currents or voltages from sources with high internal resistance by means of measuring circuits with high input impedance, e.g. OP-amplifiers (electrostatic instruments G01R5/28; measuring electrostatic potential G01R15/165; measuring electrostatic fields G01R29/12; amplifiers per se H03F) · CPC title

• G01R15/181 Primary

  using coils without a magnetic core, e.g. Rogowski coils · CPC title

• G01R19/0007

  Frequency selective voltage or current level measuring (measuring frequency G01R23/00; testing attenuation in line transmission systems H04B3/48; monitoring testing in transmission systems H04B17/00) · CPC title

• G01R19/28

  adapted for measuring in circuits having distributed constants · CPC title

• G01R19/0092 Primary

  Measuring current only · CPC title