# US 8,787,999 B2 · Fault current limited system with current splitting device

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- Number: US 8,787,999 B2
- Document ID: US8787999B2
- Status: Granted
- Kind: B2
- Application number: 13/444,379
- Filed: 2012-04-11
- Published: 2012-10-18
- Granted: 2014-07-22
- Earliest claimed: 2011-04-15
- Assignees: Varian Semiconductor Equipment Associates, Inc.
- Applicants: Kasegn D. Tekletsakik
- Inventors: Kasegn D. Tekletsakik
- Web page: https://patentgrep.com/patent/US8787999B2

## CPC

- H02H 9/021: {Current limitation using saturable reactors (H02H9/023 takes precedence)}
- H02H 9/023: {Current limitation using superconducting elements}
- Y02E 40/60: Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
- 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)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A fault current limiter system including a fault current limiter and a variable shunt current splitting device. The current splitting device includes first and second conductive windings, wherein the first conductive winding is connected in parallel with the fault current limiter and is configured to carry current in a first direction. The second conductive winding is electrically connected in series with the fault current limiter and is configured to carry current in a second direction opposite to the first direction so that the reactance of the first winding is negated by the reactance of the second winding during steady state operation of the fault current limiter system. Thus, a first portion of a steady state current is conveyed through the fault current limiter and a second portion of the current is conveyed through the current splitting device. The steady state current load on the fault current limiter is thereby reduced.

## Claims

### Claim 1

A fault current limiter system comprising:
a fault current limiter;
a shunt electrically connected in parallel to the fault current limiter; and
a current splitting device comprising first and second conductive windings wound about a core,
wherein the first conductive winding is electrically connected in parallel with the fault current limiter and the shunt, and the first conductive winding is configured to carry current in a first direction, and
wherein the second conductive winding is electrically connected in series with the fault current limiter and the shunt, and is configured to carry current in a second direction opposite to the first direction such that a first magnetic field associated with the first winding is coupled with a second magnetic field associated with the second winding during steady state operation of the fault current limiter system.

### Claim 2 (depends on 1)

The fault current limiter system of claim 1, wherein the first and second windings of the current splitting device are configured to magnetically decouple and increase an equivalent impedance of the current splitting device to limit an amount of current delivered to a load during a fault condition.

### Claim 3 (depends on 1)

The fault current limiter system of claim 1, wherein the fault current limiter comprises a superconducting fault current limiter.

### Claim 4 (depends on 1)

The fault current limiter system of claim 1, wherein the fault current limiter comprises a solid state fault current limiter.

### Claim 5 (depends on 1)

The fault current limiter system of claim 1, wherein the fault current limiter comprises an inductive fault current limiter.

### Claim 6 (depends on 1)

The fault current limiter system of claim 1, wherein the current splitting device is configured to convey an amount of steady state current less than a total system current during steady state operation of the fault current limiter system.

### Claim 7 (depends on 1)

The fault current limiter system of claim 1, wherein the current splitting device further comprises a tuning winding connected in series with the first winding for facilitating fine tuning of an impedance and current distribution of the current splitting device.

### Claim 8 (depends on 1)

The fault current limiter system of claim 1, wherein the first and second windings are wound in a bifilar coil arrangement.

### Claim 9 (depends on 1)

The fault current limiter system of claim 1, wherein the first and second windings are wound in an opposing, concentric arrangement.

### Claim 10 (depends on 1)

The fault current limiter system of claim 1, wherein the first and second windings are wound in a crisscrossed arrangement with an equal number of turns.

### Claim 11 (depends on 1)

The fault current limiter system of claim 1, wherein the first and second windings are wound in a crisscrossed arrangement with an unequal number of turns.