Fault Current Limiter

A fault current limiter comprising:

• at least one magnetisable core member having a void defined therein;
• at least one AC magnetomotive force source configured to generate a varying magnetic flux in at least a portion of the at least one magnetisable core member;
• and
• at least one static magnetomotive force source being positioned to provide a magnetic circuit within at least part of the at least one magnetisable core member characterised in that the at least one static magnetomotive force source is arranged to extend across the void.

A method of preventing a fault condition in an AC magnetomotive force source positioned relative to at least one magnetisable core member having at least one static magnetomotive force source arranged such that the AC magnetomotive force source and the static magnetomotive force source are relatively positioned to be orthogonal to each other, the method comprising:

• using the static magnetomotive force source to create a magnetic circuit within at least part of the at least one magnetisable core member so as to saturate at least part of the magnetisable core member, thereby providing a low inductance for the AC magnetomotive force source enabling current to flow along the AC magnetomotive force source in normal operation;
• producing an AC magnetic field which overcomes the saturation in at least part of the at least one magnetisable core member in the event of a fault condition;
• and
• increasing the inductance of the AC magnetomotive force source in the event of a fault condition so as to limit the passage of fault current flowing therethrough.

A method of preventing a fault condition in an AC conductive element wound around at least one magnetisable core member having at least two magnets with opposing dipole moments arranged within the at least one magnetisable core member, the method comprising:

• creating a magnetic circuit within at least one magnetisable core member;
• saturating at least part of the at least one magnetisable core member so as to provide a low inductance for the conductive element enabling current to flow along the conductive element in normal operation;
• producing an AC magnetic field which overcomes the saturation in at least part of the at least one magnetisable core member in the event of a fault condition;
• and
• increasing the inductance of the conductive element so as to limit the passage of fault current flowing therethrough,
• characterised in that the magnetic field generated by the conductive element is orthogonal to the magnetic dipole moment of the at least two magnets.

A method of preventing a fault condition in an AC magnetomotive force source positioned relative to at least one magnetisable core member having a void defined therein and having at least one static magnetomotive force source arranged to extend across the void, the method comprising:

• using the static magnetomotive force source to create a magnetic circuit within at least part of the at least one magnetisable core member, so as to saturate at least part of the magnetisable core member, thereby providing a low inductance for the AC magnetomotive force source and enabling current to flow along the AC magnetomotive force source in normal operation;
• producing an AC magnetic field via the AC magnetomotive force source which overcomes the saturation in at least part of the at least one magnetisable core member in the event of a fault condition;
• and
• increasing the inductance of the AC magnetomotive force source in the event of a fault condition so as to limit the passage of fault current flowing therethrough.

A fault current limiter (FCL) comprising:

• at least one magnetisable core member;
• at least one AC magnetomotive force source configured to generate a varying magnetic flux in at least a portion of the at least one magnetisable core member;
• and;
• at least one static magnetomotive force source being positioned to provide a magnetic circuit within at least part of the at least one magnetisable core member.