# US 2014/0192443 A1 · Magnetizing inrush current suppression device

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2014/0192443 A1
- Document ID: US20140192443A1
- Status: Published application
- Kind: A1
- Application number: 14/205,090
- Filed: 2014-03-11
- Published: 2014-07-10
- Earliest claimed: 2011-09-14
- Assignees: Kabushiki Kaisha Toshiba
- Applicants: Kabushiki Kaisha Toshiba
- Inventors: Tadashi KOSHIZUKA; Minoru SAITO; Shiro MARUYAMA; Hiroyuki MAEHARA; Koji SUZUKI
- Web page: https://patentgrep.com/patent/US20140192443A1

## CPC

- H02H 9/002: {limiting inrush current on switching on of inductive loads subjected to remanence, e.g. transformers}
- H01H 9/563: {for multipolar switches, e.g. different timing for different phases, selecting phase with first zero-crossing}
- H02H 3/08: responsive to excess current (responsive to abnormal temperature caused by excess current H02H5/04)
- H02H 3/44: responsive to the rate of change of electrical quantities
- H02H 7/04: for transformers
- H02H 7/042: {for current transformers}
- H02H 7/045: Differential protection of transformers
- H02H 9/04: responsive to excess voltage (lightning arrestors H01C7/12, H01C8/04, H01G9/18, H01T)
- 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)
- 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)

## Abstract

According to one embodiment, there is provided a magnetizing inrush current suppression device. A closing phase determination unit determines a phase position for suppressing the magnetizing inrush current among phase positions in which the prospective magnetic flux calculated by the prospective magnetic flux calculation unit and the residual magnetic flux calculated by the residual magnetic flux calculation unit coincide between the lines of the minimum residual magnetic flux determined by the minimum residual magnetic flux determination unit, as a closing phase position. A closing unit simultaneously closes the three phases of the circuit-breaker at the determined closing phase position.

## Claims

### Claim 1

A magnetizing inrush current suppression device for controlling a circuit-breaker that closes and opens connection between a transformer having a Y-connected primary winding and Δ-connected secondary winding and a three-phase AC power supply to suppress a magnetizing inrush current, the magnetizing inrush current suppression device comprising:
a power supply-side voltage measurement unit configured to measure three-phase AC voltage on a power supply side of the circuit-breaker;
a prospective magnetic flux calculation unit configured to calculate prospective magnetic fluxes between three lines of the secondary winding of the transformer based on the three-phase AC voltage measured by the power supply-side voltage measurement unit;
a transformer voltage measurement unit configured to measure respective terminal voltages of the secondary winding of the transformer;
a residual magnetic flux calculation unit configured to calculate residual magnetic fluxes between the three lines based on the respective terminal voltages measured by the transformer voltage measurement unit;
a minimum residual magnetic flux determination unit configured to determine residual magnetic flux of a minimum absolute value among the residual magnetic fluxes between the three lines calculated by the residual magnetic flux calculation unit;
a closing phase determination unit configured to determine a phase position for suppressing the magnetizing inrush current among phase positions in which the prospective magnetic flux calculated by the prospective magnetic flux calculation unit and the residual magnetic flux calculated by the residual magnetic flux calculation unit coincide between the lines of the minimum residual magnetic flux determined by the minimum residual magnetic flux determination unit, as a closing phase position; and
a closing unit configured to simultaneously close the three phases of the circuit-breaker at the closing phase position determined by the closing phase determination unit.

### Claim 2 (depends on 1)

The magnetizing inrush current suppression device according to claim 1, wherein the closing phase determination unit determines a phase position for suppressing the magnetizing inrush current among phase positions in which a difference magnetic flux between the prospective magnetic flux calculated by the prospective magnetic flux calculation unit and the residual magnetic flux calculated by the residual magnetic flux calculation unit comes to a zero point, as the closing phase position.

### Claim 3 (depends on 1)

The magnetizing inrush current suppression device according to claim 1, further comprising a phase range determination unit configured to determine a phase range in which polarities of the prospective magnetic flux calculated by the prospective magnetic flux calculation unit and the residual magnetic flux calculated by the residual magnetic flux calculation unit coincide between lines other than between the lines of the minimum residual magnetic flux determined by the minimum residual magnetic flux determination unit,
wherein the closing phase determination unit determines a phase position that lies in the phase range determined by the phase range determination unit as a phase position for suppressing the magnetizing inrush current.

### Claim 4 (depends on 1)

The magnetizing inrush current suppression device according to claim 1, further comprising an opening unit configured to open the circuit-breaker in a predetermined phase range.

### Claim 5 (depends on 4)

The magnetizing inrush current suppression device according to claim 4, wherein the opening unit determines the phase range such that an absolute value of residual magnetic flux between lines previously determined among the respective lines of the secondary winding of the transformer is set to a maximum.

### Claim 6 (depends on 4)

The magnetizing inrush current suppression device according to claim 4, wherein the opening unit determines the phase range such that an absolute value of residual magnetic flux between lines previously determined among the respective lines of the secondary winding of the transformer is set to a minimum.

### Claim 7

A magnetizing inrush current suppression method of controlling a circuit-breaker that closes and opens connection between a transformer having a Y-connected primary winding and a-connected secondary winding and a three-phase AC power supply to suppress a magnetizing inrush current, the magnetizing inrush current suppression method comprising:
measuring three-phase AC voltage on a power supply side of the circuit-breaker;
calculating prospective magnetic fluxes between three lines of the secondary winding of the transformer based on the measured three-phase AC voltage;
measuring respective terminal voltages of the secondary winding of the transformer;
calculating residual magnetic fluxes between the three lines based on the respective measured terminal voltages;
determining a residual magnetic flux of a minimum absolute value among the calculated residual magnetic fluxes between the three lines;
determining a phase position for suppressing the magnetizing inrush current among phase positions in which the calculated prospective magnetic flux and the calculated residual magnetic flux coincide between the lines of the determined minimum residual magnetic flux, as a closing phase position; and
simultaneously closing the three phases of the circuit-breaker at the determined closing phase position.