# US 2022/0044869 A1 · Current transformer of air circuit breaker

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- Number: US 2022/0044869 A1
- Document ID: US20220044869A1
- Status: Published application
- Kind: A1
- Application number: 17/414,002
- Filed: 2019-09-18
- Published: 2022-02-10
- Earliest claimed: 2018-12-26
- Assignees: Ls Electric Co., Ltd.
- Applicants: Ls Electric Co., Ltd.
- Inventors: Han-Baek CHUNG
- Web page: https://patentgrep.com/patent/US20220044869A1

## CPC

- H01F 3/12: Magnetic shunt paths
- H01F 38/30: Constructions
- G01R 15/185: {with compensation or feedback windings or interacting coils, e.g. 0-flux sensors (using galvano-magnetic field sensors G01R15/20; conversion of DC into AC using transductors G01R19/20)}
- H01F 27/427: {for current transformers}
- H01F 38/305: {with toroidal magnetic core}
- H01H 71/125: {characterised by sensing elements, e.g. current transformers (for differential protection H01H83/144)}
- H02H 1/0007: {concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445)}
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)
- H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H)

## Abstract

A current transformer according to the present invention may comprise a magnetic core, a secondary coil, and a magnetic flux compensation member. A main circuit of an air circuit breaker penetrates the magnetic core. In addition, the secondary coil is arranged to be adjacent to the magnetic core, and a secondary current is induced through a current flowing in the main circuit. In addition, the secondary coil supplies the induced secondary current to a relay. The magnetic flux compensation member may be coupled to the magnetic core so as to correct magnetic flux of the secondary coil.

## Claims

### Claim 1

A current transformer comprising:
a magnetic core through which a main circuit of an air circuit breaker passes;
a secondary coil disposed adjacent to the magnetic core to induce a secondary current from a current flowing through the main circuit and to supply the secondary current to a relay; and
a magnetic flux compensation member coupled to the magnetic core to compensate for the current induced from the secondary coil.

### Claim 2 (depends on 1)

The current transformer of claim 1, wherein the magnetic flux compensation member is coupled to both side faces of the magnetic core.

### Claim 3 (depends on 1)

The current transformer of claim 1, wherein the magnetic flux compensation member is embodied as a plate-like member having a predetermined thickness.

### Claim 4 (depends on 3)

The current transformer of claim 3, wherein the magnetic flux compensation member includes a plurality of plate-like members having a predetermined thickness and coupled to the magnetic core and overlapping each other.

### Claim 5 (depends on 1)

The current transformer of claim 1, wherein the magnetic core has a through-hole defined therein through which the main circuit passes,
wherein the secondary coil is coupled to a first shunt spaced from the magnetic core by a predetermined distance,
wherein the magnetic flux compensation member extends vertically by a first distance, wherein a virtual connection line having a shortest distance and connecting the secondary coil and the main circuit to other overlaps the magnetic core by the first distance.

### Claim 6 (depends on 5)

The current transformer of claim 5, wherein the magnetic flux compensation member includes a plate-shaped member having a predetermined thickness and having a vertical dimension equal to the first distance.